K.1 General Building Guidelines and Design Considerations
K.2 Normal Power
K.3 Emergency Power
K.4 Motor Control
K.5 Lighting
K.6 Power Quality

K.1 General Building Guidelines and Design Considerations

K.1.1 Calculations: Each electrical design should include the submittal of the following design calculations:

• Lighting calculations showing required and designed lux
• Estimated panelboard loading (including 25 percent extra as a projection of future building loads)
• A projection/summation of the panelboard loads to justify the sizing of the transformers
• An economic analysis to justify the selection of either 120/208 V or 277/480 V on the secondary side of the transformers if the proposed secondary service voltage is different from the guidelines in paragraph K.2.13
• An analysis, for the 277/480 V choice, as to whether the stepdown transformer(s) should be large central units or smaller units placed throughout the building
• A short-circuit analysis to determine the AIC rating of the system components
• A coordination study to determine the circuit breaker settings and system coordination

The architect/engineer (A/E) should prepare calculations that show the available shortcircuit currents at each bus and the voltage drop for each major cable run. Include in the calculation package an AutoCAD Drawing file in hard copy and electronic formats, showing corresponding bus and cable run identification number as in the calculations. The calculations package should be submitted to the NIH. The A/E should provide system load calculations for switchgears, switchboards, motor control centers, panelboards, busways, risers, and transformers. The A/E should provide product and photometric data sheets for all fixtures specified in the design.

The A/E should review and assess with the NIH during early design submissions the need for the contract documents to require a power system study to be provided by an independent testing company. The power system study shall be performed using SKM System Analysis Power Tools software.

The study shall be submitted to the Project Officer prior to receiving final approval of the distribution equipment shop drawings and/or prior to release of equipment for manufacturing. If formal completion of the study may cause delay in equipment manufacturing, approval from the Project Officer may be obtained for a preliminary submittal of sufficient study data to ensure that the selection of device ratings and characteristics will be satisfactory.

The study should include executive summary, assumptions, short-circuit study results, load flow study results, motor starting study results, protective device coordination results, and conclusions. The study should include all portions of the electrical distribution system from the normal power source or sources down to and including the smallest adjustable trip circuit breaker in the distribution system. Normal system connections and those that result in maximum fault conditions should be adequately covered in the study.

The independent testing firm selected should be currently involved in high- and low-voltage power system evaluation. The study shall be performed, stamped, and signed by a registered Professional Engineer. Credentials of the individual(s) performing the study and background of the firm should be submitted to the Project Officer for approval prior to start of the work. A minimum of 5 years of experience in power system analysis is required for the individual in charge of the project.

The firm performing the study should demonstrate capability and experience to provide assistance during startup as required. Contract specifications should require the contractor to provide the required data for preparation of the studies to the independent company. The contractor should expedite collection of the data to ensure completion of the studies as required for final approval of the distribution equipment shop drawings and/or prior to release of the equipment for manufacturing.

K.1.2 Design: The design documents shall be presented for review at various stages of completion as determined by the Project Officer. The comments returned from the NIH reviewers must be given careful consideration, as these are based on experience with past designs that have caused problems for research or maintenance personnel. Written responses to these comments should be provided.

K.1.3 Design Analysis Narrative: Where the design is of an unusual nature and the intent is not readily discernible, a separate design analysis narrative should be prepared to explain the intent and reasoning behind the novel design. This should be presented in the earlier stages of review to ensure that the design is suitable for NIH personnel.

K.1.4 Operational and Maintenance (O&M) Manuals: Operation and repair manuals for all electrical equipment supplied on the project are required and should be called for in the specifications. This submittal shall be made in both hard copy and electronic formats on a CD-ROM, DVD, or similar media. Scanning may be used for items that are not available electronically. A meeting should be specified to turn over the equipment inventory and O&M manuals to the Office of Research Facilities (ORF).

K.1.5 Panel Schedules: The information to be supplied on the panelboard schedules is all data necessary to order the equipment and all data needed to completely identify the attached loads. Panel schedules shall be filled in on drawings utilizing the features included in the AutoCAD electrical software. Information to be clearly shown should include the following:

• Panel name
• Number and size of spare breakers
• Number of bused spaces and the maximum ampere ratings
• Total number of breaker positions in the panel
• Top feed or bottom feed
• Main circuit breaker (MCB) or main lugs only (MLO)
• Surface or recessed mounting
• Trip rating, frame rating, and number of poles of each breaker
• AIC rating of the panel; series rating not acceptable
• Identification of the load and the room name and room number
• Estimated connected load in watts
• Estimated connected load in volt-amperes (or kVA) per circuit
• Panel total connected kVA and amperes
• Panel total demand kVA and amperes

K.1.6 Reference Design and Safety Guidelines for the Electrical Designer: The NIH is a progressive and dynamic biomedical research institution where state-of-the-art medical research is the standard practice. To support state-of-the-art research and medical care, the facilities must also be state of the art. It is the NIH’s intent to build and maintain the electrical systems and facilities in accordance with the latest standards.

It has been the NIH experience that the renovation and rehabilitation of existing facilities do not always lend themselves to incorporating the “latest” standards of the industry. Some of the existing electrical systems are outdated or inadequate for the new load. Often the planned function is incompatible with the original criteria for the building.

The A/E should be alerted to this situation and make an evaluation early in the design stage to determine the implementation feasibility of the latest standards. The A/E should document such findings, provide recommendations, and report them to the Project Officer for a decision on how to proceed.

The A/E design firm should use and comply with, at a minimum, the latest issue of the following design and safety guidelines. In addition, the A/E should use other safety guidelines received from the NIH Project Officer or as required by the program.

The reference codes, regulations, and recommended practices include but are not limited to the latest versions of the following:

• Americans with Disabilities Act Accessibility Guidelines (ADAAG)
• Association of Edison Illuminating Companies (AEIC)
• American Hospital Association (AHA), Management and Compliance Series, Electrical Systems for Health Care Facilities
• American National Standards Institute (ANSI)
• AHA, Management and Compliance Series, Fire Warning and Safety Systems
• American Society of Mechanical Engineers (ASME) A17.1: Safety Code for Elevators and Escalators
• Building Officials and Code Administrators, International (BOCA) The BOCA National Building Code
• Electronic Industries Association (EIA)
• International Cable Engineers Association (ICEA)
• International Electrotechnical Commission (IEC)
• Institute of Electrical and Electronics Engineers (IEEE), Color Books
• Illuminating Engineering Society of North America (IESNA), Lighting Handbook
• Lightning Protection Institute, LPI 175 Standard of Practice
• National Electrical Code (NEC), National Fire Protection Association NFPA Standard 70
• National Electrical Manufacturers Association (NEMA)
• National Electrical Safety Code (NESC) IEEE C2
• International Electrical Testing Association (NETA), Acceptance Testing Specifications for Electric Power Distribution Equipment and Systems
• NFPA, National Fire Codes (NFC)
• Institute of Laboratory Animal Resources (ILAR), Guide for the Care and Use of Laboratory Animals
• Telecommunications Industries Association (TIA)
• Uniform Federal Accessibility Standards (UFAS)
• Underwriters Laboratories (UL)

K.1.7 Testing and Operational Requirements: The A/E should incorporate the requirements for testing and operational training and for the startup and checkout of building systems in the project specifications.

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K.2 Normal Power

K.2.1 New Service Connection: The NIH will determine the most appropriate location for a service connection to the high voltage (13.8 kV) system on the NIH Bethesda campus. The service may require a new feeder from the nearest 15 kV substation. Contact the NIH’s senior electrical engineer for more detailed information specific to the project.

All secondary substations at the NIH Bethesda campus where the anticipated load is over 500 kilovolt-amperes (kVA) shall be spot network type. If redundancy is required at facilities other than on the NIH Bethesda campus, the senior electrical engineer may suggest a double-ended, secondary selective system for review. The secondary selective system, if used, should consist of two primary feeders, two fused load interrupter switches, two transformers, two secondary main breakers, and one tie breaker, plus the necessary feeder breakers. Secondary selective systems should be provided with automatic transfer.

K.2.2 Standard Cable Size and Type: The NIH has standardized 500 thousand circular mils (KCMIL) and 350 KCMIL as the preferred size for the 15 kV ethylene-propylene rubber (EPR) cable. The system voltage is a nominal 13.8 kV, and the NIH system is operated ungrounded. The cable is compact-sector, 133 percent insulation, shielded, with the lead sheath grounded in each manhole. Splices should be custom-made at each site by an experienced cable splicer using customized splicing kits from a reputable cable manufacturer. All splices should be started and carried through to completion without interruption, usually taking about 8 hours. EPR cable shall not be spliced to paper-insulated lead-covered (PILC) cable.

The EPR cable shall be 500 KCMIL,15 kV single copper conductor, shielded 90 °C and rated with a 100 percent insulation level. The strand screen shall be extruded semiconducting EPR meeting or exceeding the electrical and physical requirements of ICEA S-68-516, AEIC CS6, and UL 1072. The shield shall be 5 mil-thick bare copper tape helically applied with a 12.5 percent overlap. The jacket shall be a polyvinyl chloride (PVC) jacket. The cable shall be UL listed as Type MV-90 in accordance with UL 1072. Each feeder shall consist of three single-conductor cables, plus a ground wire as described
hereinafter, or a three-conductor cable with an integral ground.

Where EPR cable is installed, it shall have a copper ground conductor installed with the phase conductors. The ground conductor shall be No. 1/0 AWG minimum.

K.2.3 Distribution Duct System (DDS): The NIH Bethesda campus has two underground duct and manhole systems: one for electrical power cables and one for communication circuits. The DDS for electrical power has manholes designed with the letter “E” followed by a number (one to three digits). Where a duct line branches off an existing manhole, the new manhole will have a subletter designation. For example, the existing manhole is E-29, and two new manholes, E-29A and E-29B, are added on the same branch. The manhole designations for communications manholes will be discussed in General Design Guidelines, Section: Communications, Local Area Network.

The ducts contain only high-voltage feeders, rated 15 kV for use on the NIH nominal 13.8 kV system, and supervisory cables that monitor and control the high-voltage system. The older supervisory cables, which are in the process of being replaced, were multiconductor control cables. The NIH has continued a process of replacing these cables with smaller diameter data links over fiber-optic paths in the existing campus local area network (LAN) cables and over telephone lines.

The area surrounding manholes in grass areas shall be regraded to drain away from the manhole cover. Manhole covers shall be 13 mm above finish grade. Manholes shall be provided with a sump approximately 300 mm x 300 mm x 150 mm deep. Preferably, manholes should be located in grass areas first, sidewalks second, and in the street last. Manholes shall not be located in parking spaces. Where ducts are sloped from a high to a low manhole, they shall be sealed at the high end only to allow condensation to drain. Cables in manholes shall be labeled with embossed brass cable tags and brass chains. Manholes shall be provided with two manhole covers, one for forced air and materials entry and the other for worker access. The standard manhole frame and cover shall be 700 mm in diameter (600 mm inside diameter). Manhole covers shall be labeled “ELECTRIC” for power and “TELEPHONE” for communications. The cover shall have a small, flat area for labeling, with the manhole number applied by a welded bead. An embossed brass tag with the manhole number shall be permanently mounted inside the chimney and legible from outside the manhole with the cover removed.

K.2.4 Elevation Considerations: The DDS consists of multiple duct runs between manholes of 155 mm inside diameter PVC Schedule 40 ducts with a concrete encasement. The encasement has steel reinforcement in a plane just below the lowest row of ducts where the duct run spans disturbed earth, where it enters manholes and buildings (out to 1.8 m), and where it crosses under heavily traveled roadways. The spacing between ducts is 75 mm in all directions. The ducts shall be 760 mm minimum clear below grade or top of roadway.

Duct runs shall be sloped from the higher manhole entrance to the lower manhole entrance with no intermediate low spots that would pool moisture. If manhole entrance points are on about the same level, then there must be an arch in the duct run so that there is drainage from a high point into both manholes. If a low point is absolutely unavoidable, another manhole shall be provided at or near the low point.

K.2.5 Grounding: Each manhole shall be equipped with a 3 m-long, 20 mm copper-clad steel ground rod through the floor of the manhole, with all metallic components in the manhole, such as racks, cable sheaths, or ladder, securely grounded to this rod with a #6 American Wire Gauge (AWG) green insulated cable.

K.2.6 Maximum Length Between Manholes: The maximum cable length between manholes shall be kept to less than 120 m for an essentially straight run and reduced by 15 m for each bend of 0.79 radians and by 30 m for each bend of 1.6 radians. Bends shall be made with the largest radius possible. This by no means releases the A/E or the contractor from doing the necessary cable-pulling calculations to ensure that the maximum tension or sidewall pressures are not exceeded.

K.2.7 Spare Capacity: When new duct runs and manholes are installed, additional ducts shall be provided for future expansion. There shall be at least two spare ducts included with the required ducts, more if this will round out a duct bank to a symmetrical configuration. Odd numbers of duct, such as 7, 11, or 13, shall not be constructed.

K.2.8 Normal Power: The NEC load figures shall be used in sizing the overall building service for an office building. For load figures on laboratories, animal research facilities, and hospitals, see the respective sections. The connected load shall be used in the early design stages. Actual design loads shall be used in the later part of the design. The mechanical loads do not include chilled water or steam generation, which are produced centrally on the NIH Bethesda campus. The A/E shall use sound judgment in applying load calculations to these numbers.

Table K.2.8 Load Calculations

K.2.9 Network Transformers and Spot Network Equipment: The typical building service should utilize a three-transformer spot network. Each transformer shall be sized for 50 percent of the total building load, including any spare or future capacity. Building 10 has multiple services with both three- and four-transformer spot networks. See Figure K.2.9. All liquid-filled transformers shall be provided with Factory Mutual-approved, less flammable natural ester similar to Envirotemp FR3 or approved equal.

Figure K.2.9 Single Line Diagram: Typical Building Service

Limit main and tie circuit breakers and busing to 4 000 A or less in any spot network configuration.

The spot network configuration shall be sized to allow one network transformer to be removed from service, with the remaining spot network transformers capable of carrying the entire load indefinitely without transformer-forced cooling, plus an additional 25 percent spare capacity designated for future modifications on the electrical power distribution system.

Each secondary spot network shall include a primary 15 kV switch, network transformer and a secondary network protector and disconnect device. The manufacturer of the spot network substation shall furnish and coordinate all major components of the substations, including incoming primary equipment section, network transformers, and low-voltage network protector and disconnect device as well as control devices, protective relays, and metering components. A single warranty covering all substation assemblies, transformers, and components should be provided. The spot network substation shall be designed, assembled, tested, and installed in accordance with the latest applicable standards of NEMA, IEEE, and ANSI applicable to network transformers and network protectors. The network protector shall be a maximum-rated device as manufactured by Cutler-Hammer. The network protector shall be a fully interlocked, dead-front, draw-out design with externally mounted fuses for easy removal of the unit from enclosure for maintenance and inspection by operating hand-cranked levering system. Relay and control panels shall be mounted on draw-out control module below network protector element. Protectors shall comply with the IEEE C57.12.44 standard. The network protector shall have a mechanism controlled by a toggle-cam device that will not allow closure of the contacts until the springs contain sufficient energy to close and latch the contacts onto available fault current. Each network protector shall have a disconnect switch mounted on top of or on the opposite wall from the network protector. The disconnect is a maintenance isolation switch for working on the network protector. Disconnecting links are no longer allowed for safety reasons.

Each network protector shall be provided with an Intelligent Electronic Device (IED).

IED shall be the three-phase type with relay functions to provide selective closing and tripping of auxiliary contacts mounted on the relay and interfaced with the protector circuitry. The relay close contact shall close if the ensuing positive sequence power will be into the network. The relay trip contact shall close when there exists a net three-phase balanced reverse power flow through the network protector. The trip contact shall also close upon flow of reverse magnetizing current of its associated transformer.

The relay shall be enclosed in a NEMA Type 6 chemically treated, waterproof drawn brass shell, and any wiring to the relay (including communication wire) shall not compromise the rating. The relay shall offer three on-board input ports that are used for external sensors when combined with the communication package. The relay shall offer internal air temperature with the communication package. The relay shall utilize the capability of choosing from the traditional straight-line master close curve and the modified circular closed curve. The relay shall utilize insensitive phase rotation.
The microprocessor relay shall operate under the sequence-base algorithm, which provides a flat, unchanging trip response. The relay shall operate in a temperature range of -20 to +110 °C with exertions to +125 °C. The relay shall have the capability to communicate information to a data concentrator over a shielded twisted pair communications wire.

K.2.9.1 Location: The transformers should preferably be located indoors in a transformer vault. The alternate location is outdoors in a pad-mounted configuration.

Transformers located indoors shall preferably be in the same room (vault) as the secondary switchgear or in an adjacent transformer vault. Pad-mounted network transformers shall be located outside the service entrance switchgear room. The secondary service conductors shall be kept as short as possible.

K.2.9.2 Removal Route: The size of transformers and the requirements for power reliability at the NIH require that there be an exit route specified for these large, heavy items of electrical equipment. The A/E of the building must provide for a permanent exit route to remove these large items and bring in new units. Note that the faulty unit must be removed while the other one, two, or three transformers remain in place and in operation. The suggested method is to use painted stripes and warning signs on the floor and walls along the exit route.

K.2.9.3 Primary Switch: The 15 kV primary switch is a three-position, no-load break switch. The three positions are OPEN, CLOSED, and GROUND. The closed position is the center position. The switch is key interlocked with the transformer tap changer mechanism such that it must be in the ground position before the transformer taps can be changed.

K.2.9.4 Transformer: Transformers shall have temperature gauges with resettable maximum pointers, sampling valves, high-pressure release valves, and a key-interlocked tap changer. The transformers shall be filled with an approved less flammable natural ester liquid similar to Envirotemp FR3 or an approved equal. The tap changer shall have five settings, two above and two below the 100 percent rating. Each tap shall represent 2.5 percent of nominal voltage. Transformer windings shall be copper and full kVA rated.

K.2.9.5 Network Protector: The network protector shall contain time delays and other controls to prevent “pumping,” which is the cyclical opening and closing of the network protector. Spot networks shall include a remote terminal unit (RTU). The RTU is a multiplexing device that sends monitoring and control signals from the respective building to the campus-wide Supervisory Control and Data Acquisition (SCADA) system.

The RTU shall be located in either the transformer vault or the secondary switchgear room and requires a 120 V circuit. The output control voltage is 48 V DC. The network protectors shall have auxiliary relays with 48 V DC coils for shunt tripping by the RTU. The RTU should include monitoring the following devices/functions:

• Pressure and temperature of liquid-cooled network transformers
• Status of network protectors
• Status of all secondary main and tie circuit breakers
• Status of any battery bank systems in substations

The RTU should include controlling the following devices:

• Tripping of network protectors
• Opening and closing of secondary main and tiebreakers

The RTU shall include analog inputs to measure:

• All secondary switchboard metering

The RTU is provided with a number of analog and digital sensing points, as well as a number of relays for the control functions. The number of points can be augmented in the future as additional points are needed or defined.

K.2.10 Secondary Switchgear: Secondary low-voltage switchgear shall be the freestanding, metal enclosed type. The switchgear shall have a main circuit breaker on the secondary of each unit substation transformer. Circuit breakers shall be draw-out air power circuit breakers or draw-out vacuum circuit breakers. The switchgear shall be the ANSI metal enclosed, draw-out type. Spare cubicles, minimum one cubicle per frame size utilized in the switchgear lineup, should be provided. All spaces shall be fully bused based on frame sizes required to be indicated on design drawings, including draw-out assemblies, bused connections, and hardware. Molded case circuit breakers are not allowed in switchgear construction. All cubicles shall be complete, with buswork, rails, wiring, and circuit breakers. All buses shall be copper. The switchgear shall be positioned to allow for the addition of a minimum of one vertical section to the switchgear provided that switchgear capacity is not exceeded.

The electrical arrangement of the switchgear is shown in single-line form in Figure K.2.9. The switchgear shall have a main circuit breaker for each network protector. Each main circuit breaker shall serve a section of the main bus. The sections shall be connected by tie breakers of the same ratings as the mains. The main and tie breakers are normally closed and electrically operated. The normally closed breakers form a spot network. The tie breakers will sectionalize the main bus should a fault occur, thereby minimizing the outage to one section of bus. The breakers are electrically operated to allow remote operation by the campus SCADA system.

Circuit breaker selection shall accommodate the inherently high-available short-circuit interrupting current in a spot network system arrangement.

Where automatic transfer is provided, the secondary main breakers and tie breaker shall be electrically operated with manually and electrically operated trips. Feeder circuit breakers shall be manually operated. Where automatic transfer is not provided, all breakers shall be manually operated.

For a spot network system, a unique dual ground bus arrangement is required for proper selective ground fault operation and isolation of a fault.

Where ground fault protection is required on main circuit breakers, it shall also be provided on feeder circuit breakers to provide selective tripping of the breaker closest to the fault. The switchboard shall be provided with a digital power meter measuring total power output of the switchboard.

The control power for low-voltage circuit breakers shall be 120 V AC. Over-current devices shall have short-time, long-time, ground fault, and instantaneous trip settings. Each incoming line shall be provided with overvoltage and undervoltage and phase sequence protection.

Digital readout metering shall be provided on the load side of each main circuit breaker. The following minimum metering is required:

• Volts (phase to phase and phase to neutral)
• Frequency
• Ampere demand (per phase and average three-phase)
• Kilowatt hours (resettable)
• Kilowatt demand (three-phase)
• kVA demand (three-phase)
• Harmonic load content (percent THD)
• Power factor

The above-mentioned local metering is in addition to the required SCADA metering, monitoring, and control system.

The switchgear shall include the provision of a control power transformer associated with each switchgear section and the necessary switching logic so that there will be 120 V relay and control power if any one of the three network transformers is energized.

The breakers in the secondary switchgear shall be either draw-out air circuit breakers or draw-out vacuum circuit breakers. Molded-case circuit breakers are not allowed. Switchboard construction is not allowed. Each breaker shall have self-contained local digital metering with remote reporting capability. The following values shall be metered:

• Volts (phase to phase and phase to neutral)
• Amperes
• Kilowatt hours (resettable)
• Kilowatt demand
• Kilowatt peak demand

Each switchgear lineup shall have a hoist provided for lifting the circuit breakers from their withdrawn position and lowering them to a dolly or to the floor. A rail assembly shall be provided along the top of the switchgear with a hoist mechanism that can roll from end to end. Spaces in switchgear shall be fully bused. Spaces shall have insulated covers over bus stabs and a complete draw-out mechanism ready for breaker installation.

Switchgears shall be located in electrical rooms dedicated to such use. No piping, ducts, or equipment foreign to the electrical equipment shall be permitted to be installed in, enter, or pass through electrical rooms in accordance with NEC requirements.

Electrical equipment that requires specialized tools for installation, maintenance, calibration, or testing shall have such tools supplied with the associated equipment and turned over to the Project Officer for delivery to the NIH Electric Shop at the end of the construction project. These tools can be as simple as a special screwdriver for vandal-proof lighting fixtures or the very complex test and calibration equipment needed to maintain solid-state circuit breakers. The argument that says tools are proprietary is not acceptable, and withholding the tools shall be cause for nonacceptance of the respective equipment.

K.2.11 Distribution Transformers: Distribution transformers shall be delta primary with solidly grounded wye-connected secondary. The transformer shall have self-cooled capacity for 100 percent load plus 25 percent capacity for future load after completion of construction. Liquid-filled transformers shall be filled with an approved less-flammable natural ester similar to Envirotemp FR3 or approved equal. Liquid-filled transformers shall be provided with liquid level, pressure/vacuum, and temperature gauges with alarm contacts.

K.2.12 Load Segregation: Wherever possible, loads shall be segregated into like groups based on function or type of load. Examples of functions are laboratories, offices, health care, animal research facilities, and so on. Examples of types of loads are computers, motors, lighting, receptacles, and so on.

K.2.13 Work Space: The following clearances are required on new projects around secondary switchgear:

• 1 500 mm in front minimum
• 1 100 mm in rear minimum
• 900 mm on the ends minimum

Renovation projects shall have at least the code minimum clearances.

All substations, switchboards, transformers, and, in general, panelboards, shall be installed in dedicated electrical rooms or closets or, if outdoors, in areas protected against physical and water damage. Pipes and ductwork shall not be routed through electrical rooms or closets. Pipes or mechanical ducts shall not be routed directly above electrical equipment. At least one duplex receptacle and 25 percent of the lighting fixtures in electrical rooms, electrical closets, communication rooms, communications closets, and mechanical rooms shall be connected to emergency power, if available. Each electrical room and electrical closet shall have at least one receptacle, and each communication room and communications closet shall have at least two receptacles installed. A finished ceiling is not required. Electrical and communication rooms and closets shall be located central to the loads served.

Electrical rooms containing substations or switchboards shall be sized to provide clear space around the equipment. Where located within buildings that are air conditioned, such rooms shall be air conditioned, if practicable. In other locations, the room shall be ventilated to maintain the temperature at not less than 8 °C and not more than 33 °C and the humidity at a noncondensing level. Ventilation shall be filtered forced air.

Adequate space shall be provided for the installation and removal of equipment without requiring disconnection of any other equipment except that which is specifically connected to the piece of equipment to be removed. Where columns are within the rooms, they shall not encroach on the space required around equipment.

Electrical closets shall be provided in sufficient quantity, size, and location to allow for top and bottom conduit entry and exit from the closet. Space shall be provided in electrical closets for installation of future conduit and equipment. Closets containing transformers or other heat-producing equipment shall provide adequate ventilation.

K.2.14 Voltage: The standard voltages on the NIH Bethesda campus are:

Table K.2.14.1 Standard Voltages

• Lighting fluorescent or HID 277 V (120 V, if building service is 120/208 V)
• Incandescent lamps (may be used only if noted in program of requirements) 120 V
• Heating (electrical heating only if a request for variance is made and approved)

Table K.2.14.2 Electric Heat Voltage and Phase

Table K.2.14.3 Motor Phase

Motors furnished at single phase as integral parts of variable air volume terminal units are acceptable for all horsepower (hp) ratings.

The secondary service voltage selection shall be based on load. The preferred voltage is 480/277 V. Typically a building load of 750 kVA or less could operate on 208/120 V unless there are compelling reasons to use 480/277 V. An economic analysis shall be performed to determine the best choice of voltage rating where the decision is unclear.

If 480/277 V is the chosen voltage, then a decision must be made where the transformation is to occur for 208/120 V loads, either at centrally located transformers or at dispersed smaller transformers close to the load. An economic analysis shall be performed where the choice is not clear.

K.2.15 Reliability: The A/E shall evaluate the degree of reliability required for a given project. Design issues such as separately routed primary feeders, two versus multiple network transformers, transformer placement, and switchgear location all bear on the reliability issue. Emergency power choices will be discussed in that section. The value of the work being performed in the given building and the impact on research due to an outage must be considered.

K.2.16 Testing: Acceptance testing of primary cable, primary switches on network transformers, network protectors, secondary switchgear motor control centers, generators, and automatic transfer switches shall be performed in accordance with NETA specifications. The minimum tests required for the given equipment are shown in Table K.2.16.

Table K.2.16 Tests Required for Electrical Equipment

K.2.17 Wire Color Coding: Wire insulation shall be color coded. Branch-circuit conductors shall have colored insulation. Larger conductors shall be taped with the appropriate color tape for a minimum 150 mm starting from the termination. Each conductor of multiconductor cable shall be color coded in the same manner as single conductors. Color coding shall be as shown in Table K.2.17 for power conductors in the given voltage systems:

Table K.2.17 Color Coding for Wire Insulation

Color coding for control cables may be of a uniform color provided permanent, numbered tape markers are placed on both ends and splice points of each conductor.

Direct burial of power and signal cables shall not be allowed. Where an existing directburied street lighting circuit is being extended one or two poles, the circuit may be directburied. Where the cable is direct-buried, it shall be protected the full length by 25 x 150 mm nominal pressure-treated lumber 150 mm above the cable. The cable shall be buried 750 mm below grade. Plastic cable-marking tape 150 mm wide shall also be installed 300 mm below grade. The plastic marking tape shall be red or yellow and read “CAUTION: BURIED ELECTRIC LINE.” Where new circuits, street lighting or otherwise, are installed underground, they shall be placed in PVC Schedule 40, rigid galvanized steel (RGS), or PVC-coated RGS conduit.

K.2.18 Conduit: Conduit should be classified by a nominal transition to metric.

Table K.2.18 Conduit Size Transition

Conduit shall be metallic to provide a redundant ground path. PVC or aluminum conduit is not acceptable except as noted below. PVC conduit may be used in underground applications and shall be used in concrete ductbanks.

All service and feeder conduit routing shall be clearly shown on the contract drawings. Homerun with panel designation and circuit numbers should be provided for circuiting. Provide the circuit number next to each arrow. All switchlegs and circuit continuations shall be indicated on the contract drawings. The contract drawings shall clearly indicate where conduits are to be installed in an exposed manner and where they are to be installed in a concealed manner. The couplings used on electrical metallic tubing (EMT) shall be the rain-tight compression type. Setscrew couplings are not allowed.

The minimum conduit size shall be 21 mm. Surface-mounted conduit in washdown areas shall be IMC or RGS with threaded couplings. Flexible metal conduit (Greenfield) shall be used for lighting fixture connections (whips) and for connections to equipment subject to vibration, noise transmission, or movement. Lighting fixture connections shall be made with minimum 1.2 m and maximum 1.8 m lengths of flexible metal conduit in accordance with NEC 410-67. Liquid-tight, flexible metal conduit shall be used for motor connections and undercabinet lighting. Raceway systems shall be provided for all wiring.

K.2.18.1 Conduits (Within Buildings): The minimum-size conduit shall be 21 mm except as indicated for flexible conduit. All conduit shall be installed parallel with the building features, except for conduit run in or under the slab. Conduit shall not be installed in the slab on grade. Fittings for metallic conduits shall be compression-type steel or malleable iron. Conduit shall not be attached to box covers, except for 15 mm or smaller flexible conduit terminated on a flush-mounted box cover. All service and feeder conduits shall be marked with machine-made labels every 15 m indicating their use. All conduits shall be supported independent of other systems and equipment and shall be supported with approved devices (tie wire is not acceptable). Conduit shall not be run exposed on top of roof surfaces.

In addition to the requirements of codes, conduit shall be installed as specified below.

RGS conduit with threaded fittings shall be used in the following locations:

• Elevator shafts, all exterior areas, and other areas where physical damage is probable.
• Where exposed within 2 400 mm of the finished floor level and a point above 2 400 mm past the vertical to horizontal transition.
• Biosafety Level 3 and 4 areas.
• Where exposed in animal research and animal holding facilities.
• Where exposed in parking structures.

PVC schedule 40 nonmetallic conduit shall be used in the following locations:

• Below concrete floor slab on grade.
• Within concrete walls or within floors above grade.
• Where elbows are terminated above slab, provide RGS elbows.
• PVC conduit stubbed out of floors shall transition to RGS raceway prior to the point where the conduit is exposed.
• RGS conduit may be substituted for PVC schedule 40.
• Electrical metallic tubing (EMT) may be used where allowed by code in all other interior spaces. All fittings used with EMT shall be compression type.

Aluminum conduit should be used in magnetic field, e.g., MRI, NMR, areas.

Steel modular surface metal raceway may be used in offices, laboratories, and similar applications where appropriate and when an area is classified as a dry location.

Cable tray may be used where dedicated for communications wiring or where dedicated for racking medium-voltage cabling (subject to the approval of the NIH).

See Conduit Support Detail, Figure K.2.18.1 below.

Figure K.2.18.1 Conduit Support Detail

K.2.18.2 Raceways (Underground): All underground conduits shall be PVC or RGS. Conduits shall be concrete encased when buried beneath roadways or when used for medium-voltage applications. Minimum size for conduits used for medium voltage shall be 129 mm. Generally, conduits serving exterior pole-mounted lighting fixtures shall be 53 mm in size. Direct-buried conduit is acceptable for electrical systems rated 600 V and below. Rigid steel may be direct-buried if coated with asphalt paint or PVC.

PVC electrical conduit for underground runs shall be a minimum of type EB if concrete encased or schedule 40 if direct-buried. Marking tape indicating “ELECTRICAL CABLE BURIED BELOW” shall be installed in accordance with the latest applicable industry standards. All empty ducts shall be provided with 4 mm minimum diameter nylon pull wire for pulling future cables.

All empty ducts shall be sealed to prevent water seepage into the handhole or manhole. Ducts shall be sloped to prevent water drainage into the building.

Prior to pulling cable into any conduit (whether new or existing), the conduit shall be cleaned with a wire brush 16 mm larger than the duct and rodded with a mandrel 8 mm smaller than the duct to test the integrity of the duct.

K.2.19 Manholes and Handholes: Manhole and handhole spacing shall be as re-quired by code and by wire-pulling requirements but not more than 150 m apart. The minimum inside dimension of manholes shall be 3 700 mm x 2 750 mm x 1 980 mm. Handholes shall be minimum 610 mm x 610 mm x 610 mm.
Handholes shall have steel covers. Handholes shall not be used on medium-voltage power systems. Covers shall be grounded. All cables shall be racked on nonmetallic cable racks designed for installation on walls of manholes. Handholes and manholes in streets shall meet Maryland Department of Transportation Standards.

K.2.20 Surface Metal Raceway: Surface metal raceway shall be metallic; plastic is not acceptable. The nominal dimensions of the raceway shall be:

Table K.2.20 Raceway Dimensions

Emergency circuits shall not be wired with normal power in the same raceway. Power and communications shall be in separate channels.

K.2.21 Busway: Busway shall have all copper bus; maximum ampacity for one busway riser should be limited to 2 000 A. Aluminum busway shall not be acceptable. Ventilated busway shall be installed in dry locations not subject to moisture. Non-ventilated busway may be installed in wet or dry locations. The contractor shall be responsible for fieldmeasuring for the busway prior to ordering. See Busway Vertical Riser Detail, Figure K.2.21, below.

Figure K.2.21 Typical Busway Vertical Riser Mounting Detail

K.2.22 Cable Tray: Galvanized steel is the preferred material to be used in ladder cabletray construction for power cables. Ladder or center-spine cable-tray construction is acceptable for communications cable. Other materials such as PVC-coated steel and aluminum will be considered. Cable trays shall consist of factory- manufactured units that bolt together in the field. Fabrication in the field, other than the shortening of a single straight section, is prohibited. Ventilated tray bottoms, in lieu of ladder rungs, are not acceptable.

Cable-tray locations shall be coordinated with adjacent utilities so that the tray will be accessible for adding or removing cables in the future. Routing shall also be adjusted so as not to obstruct access to other utility items that would routinely require access for maintenance or adjustment.

The cable trays shall be supported directly from the building structure above wherever possible. The spacing of the support points shall be as recommended by the cable-tray manufacturer. A minimum #6 AWG grounding conductor run continuously in the cable tray should be bonded to each section.

Cable trays shall not be allowed through fire-rated walls. A minimum of two 103 mm RGS sleeves with insulated bushing extending minimum 150 mm on each side of the fire-rated wall should be provided.

K.2.23 Panelboards: Circuit breakers shall be the bolt-on type. Plug-in breakers are not acceptable. The breaker shall have a published ampere interrupting rating at 125/250 V DC. This latter requirement is sometimes referred to as requiring an E-frame breaker. (A DC rating for one-pole and two-pole breakers shall be assumed by the NIH to extend to the three-pole device as well, for purposes of this requirement.)

Every panelboard shall have a main breaker in the same enclosure, closet, or room. The main breaker can be likened to a local disconnect and must be readily accessible should the panelboard need to be de-energized in an emergency situation. Single-pole breakers shall not be ganged to form multi-pole breakers. Series-rated equipment is not acceptable.

The panelboard directories shall be typed and shall reference the actual room numbers for the circuits. This shall be specified as part of the contractor’s responsibility regardless of room numbers used on the drawings. The directory shall list the panelboard name and the name of the panel fed from.

New panelboards shall allow for 25 percent future load capacity. New panelboards shall contain 25 percent spare circuit breakers after completion of construction. The spare breakers shall be left in the “OFF” position, and the panelboard directory card shall list the word “SPARE” for these breakers. New panelboards shall contain space for future circuits that amount to at least 25 percent of those required in the initial design.

Panelboards shall be located in electrical rooms or closets with code-required clearances and 76 mm minimum separation.

Bathrooms, labs, or other rooms requiring floor drains or plumbing in the floor shall not be located above electrical rooms or closets. No pipes, ducts, or equipment foreign to the electrical equipment shall be installed in, enter, or pass through electrical rooms or closets.

Branch circuits shall not be served from panelboards located in an adjacent building, area, wing, or a different floor, except for buildings with interstitial utility distribution where branchcircuit panels are located on the interstitial floors.

Panelboards shall be labeled with name and feeder source panel or riser source location. The nameplate shall be a phenolic laminate with engraved black letters on a white surround. Emergency panels shall be white letters on red surround. The panel name shall have 13 mm high letters. The words “FED FROM PANEL XX OR SWGR XX” shall be 7 mm high on a line below the panel name.

Panelboards shall have a 100 percent neutral bus and a ground bus, and all buses shall be copper. Panels serving high harmonic load content (50 percent nonlinear load) shall have a 200 percent neutral bus. All panelboard breaker busing (extension fingers), including spaces, shall be rated for 100 A minimum.

Distribution panels shall be defined as those panels serving branch-circuit panelboards and other three-phase loads. Distribution panels shall be labeled “DP-1, 2, 3,” and so on. Table K.2.23 shall be used in sizing distribution panels for future space allocation.

Table K.2.23 Distribution Panel Sizing

Branch-circuit panelboards shall have 42 poles regardless of bus ampacity. Branch-circuit panelboards shall be three-phase, four-wire, with ground bus and all copper busing.

Panelboards 400 A and above shall be provided with a hinged trim feature with a full-height piano hinge. The trim shall hinge open with the removal of a few screws. The panel door giving access to the circuit breakers only shall have a flush tumbler lock. All panelboard doors shall be keyed alike.

K.2.24 Electrical Closets: Electrical closets generally contain branch-circuit panelboards. The closets require adequate space for code-required clearances, lighting, ventilation, and two duplex receptacles. In new work and complete renovations, electrical closets shall be minimum 1.5 x 2.4 m for closets without transformers and minimum 1.8 x 3 m for closets with transformers. Closets with transformers shall have ventilation (and/or cooling) sufficient for 2 percent of the total transformer kVA expressed in watts of heat load. Electrical panelboards shall be located such that the farthest 120 V device served is within a 23 m radius of the closet. A square superimposed in a 23 m radius circle has an area of approximately 900 m². Therefore, electrical closets shall generally be placed one for every 900 m² of area served by 208/120 V branch-circuit panelboards. Loads served with 277 V shall be no more than a 30 m radius from the closet. Converting to area, lighting panels shall be placed approximately one every 1 800 m². Obviously, building configuration will change the area/closet, but the 23 m rule shall be maintained to avoid having to increase branch-circuit wire size for voltage-drop reasons.

If this closet space is not available in small renovation work, shallow closets with full doors on the long wall are acceptable in corridors. Panelboards in laboratories and animal research facilities are generally located in service corridors and do not require closets.

Electrical closets within multistory buildings shall be stacked. The closets shall not be located adjacent to mechanical shafts so as to avoid interference problems with ducts and conduits above the ceiling directly outside the closet. Mechanical ducts, piping, and work not serving the area shall not run through electrical closets as stated above per the NEC.

Lighting in electrical closets shall be one, two-lamp fluorescent strip for a small closet and two fixtures for a large closet. The lighting shall be connected to emergency power when available. One duplex receptacle shall be wired to emergency power and one to normal power in each electrical closet.

During renovation work, the designer shall not obtain new circuits from panelboards in remote areas or other floors of the building. Holes in the floors of electrical closets shall be sealed watertight. Wherever possible, the floor shall be provided with sleeves extending at least 70 mm above the floor.

K.2.25 Boxes and Wiring Devices: The color coding shall be as follows:

Table K.2.25 Color Coding

K.2.25.1 Special Requirements:

All electrical outlets in Pediatric Patient Care Units (PPCUs) shall be tamper proof.

Receptacles shall be installed so that the ground prong is mounted in the up position unless mounted 1.67 m above finished floor or higher. This is a safety requirement in the event the plug is partially pulled out and something metallic falls on the prongs of the plug. Where isolated ground circuits are required, an isolated ground conductor shall be installed with the branch circuit. See General Design Guidelines, Section: Electrical, Power Quality, for panelboard-isolated ground bus requirements.

Offices shall have a minimum of one general (ivory) receptacle per wall.

In Building 10, Ambulatory Care Research Facility (ACRF), and Clinical Research Center (CRC), standard receptacle colors are ivory for normal power and red for emergency power. Receptacles for computers and printers shall be provided with engraved nameplates.

General-purpose receptacles shall have a design load of 180 VA each in accordance with the NEC. For circuiting purposes, a maximum of six receptacles shall be connected to a circuit. This allows for future expansion of two receptacles per circuit.

Personal computers (PCs) shall be limited to three per 20 A circuit. Printers shall be limited to two per 20 A circuit. Computer and printer receptacles shall not be connected to the same circuit nor to the general (ivory) receptacle circuits. These circuits shall be provided with dedicated neutral conductors.

GFCI receptacles shall not be wired to protect downstream receptacles except in indoor installations where the downstream receptacles are in the same room.

Tamper-proof, safety-type receptacles are required in pediatric, psychiatric, and child care areas. Tamper-proof receptacles shall operate with a two- or three-prong plug.

Special duplex or single receptacles to serve specific equipment or loads shall be indicated by NEMA configuration.

A 20 A duplex receptacle shall be mounted within 7.6 m of and on the same level as any electrically operated equipment on rooftops, in attics, and in crawl spaces. The receptacle must be on a separate circuit from that serving the equipment. Receptacles mounted outdoors shall be the GFCI type.

Boxes for interior electrical systems shall be hot-dipped galvanized steel or malleable iron and shall be compatible with the raceway system.

Duplex receptacles shall be specification grade rated at 20 A, 125 V, and be polarized parallel-blade-type with ground and NEMA 5-20R configuration. Receptacles in patient care areas shall be hospital grade. The mounting brackets shall be extra heavy, and the terminals shall be copper alloy. The receptacle shall be side-wired. Cover plates for receptacles, switches, and boxes shall be stainless steel or brushed aluminum. Receptacles shall be identified according to normal power, emergency power, or computer power with isolated ground.

Toggle switches used to control lighting shall be specification grade rated for use on 120 V and 277 V circuits and shall be rated for a minimum of 20 A.

Occupancy sensor switches shall be the multitechnology type combining both ultrasonic (US) and passive infrared sensing (PIR). These switches shall be used in offices, rest rooms, and conference rooms. For mechanical rooms and service areas, smart switches with timer controls shall be provided.

K.2.26 Demolition: If the work requires that wiring be removed from conduit that is not embedded in concrete and if that conduit is not scheduled for reuse on the same project, then the conduit is to be removed.

Exceptions:

• The lighting switchleg conduit is connected to the first outlet box if the wall containing the switch is to remain.
• Vertical conduit is connected to the first outlet box at panelboard if the panelboard is of the recessed type.

If the work requires that the wiring be removed from an embedded-in-concrete conduit and if that conduit is not scheduled to be reused, the conduit is to be abandoned in place. Conduit that enters the slab from below is to be cut, after the wires are removed, as close to the slab as practical but with not more than 19 mm protruding. Conduit that enters the slab from above shall have the floor material removed so that the conduit can be cut with a cold chisel at least 6 mm below the slab elevation. Then the conduit and enlarged opening shall be plugged with nonshrinking grout and the slab surface finished flat and true.

K.2.27 Disconnects: Disconnect switches shall have a minimum clear mounting height of 460 mm above grade outdoors and 1 m above finished floor in interior spaces.

K.2.28 Electric Heat: Electric heating will not be used to heat NIH buildings. Very limited use of electric heating will be permitted provided the engineering staff of the NIH Division of Engineering Services concurs that this is the only feasible solution to an atypical situation.

K.2.29 Nameplates: All electrical equipment shall have nameplates identifying the name of the piece of equipment or the name of the equipment served (e.g., disconnects, starters, etc.). Nameplates shall be laminated phenolic legend plates with white letters on black surround for normal power and white on red surround for emergency power. Nameplates shall have minimum 7 mm-high letters for small equipment and disconnects, 13 mm high for medium-size wall-mounted equipment such as panel boards and individual Size 2 starters and above, and 50 mm high for freestanding equipment such as large panelboards, switchgear, and liquid-filled transformers. The nameplates shall be attached with stainless steel screws. Where the equipment is remote from its electrical source, under the equipment name in smaller letters the words “FED FROM” followed by the source panel or riser name shall be included.

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K.3 Emergency Power

Historically, the NIH has experienced outages of 1 hour or less once a year and outages of 4 hours or less once every 10 years. Generators are exercised weekly with a load bank, and automatic transfer switches (ATSs) are exercised monthly. The exercising of an ATS causes two momentary outages to the load, one going to diesel power and one returning to normal.

Generators shall be rated for 100 percent varying load standby rating.

Emergency loads are those that are considered necessary for life safety. They shall be wired separately from normal-powered, optional standby, and any other loads and provided with emergency generator or battery “backup” power. This category shall include:

• Emergency egress lighting
• Security and intrusion alarm systems
• Signage (egress only)
• Communication systems (including public address systems)
• Fire alarm systems
• Fire-suppression systems, such as deluge systems, CO₂ extinguishing systems, and kitchen hood fire extinguishing systems, shall be supplied with emergency power if it is available in the building.

Standby loads are loads for which it is desired to provide backup power to prevent damage to the facility, aid in rescue or evacuation, or aid in continuing operation of the facility in a limited capacity. This category also includes legally required standby loads. This category may include:

• Sewage ejector systems
• Additional lighting
• Critical exhaust and supply systems

The following loads are required to be connected to emergency power. These loads are in addition to any emergency loads that are required by code:

• Supply circuit (as required) for each uninterruptible power supply (UPS) provided by the user.
• Automatic temperature control system components.
• Auxiliary electrical system that supports the building heating system. The A/E shall study inclusion on emergency power and include on generator if required by program function.

The following loads may be connected to emergency power:

• Closed-circuit television cameras and equipment
• Security system

The requirement for emergency power for fire pumps shall be determined individually for each case, as required by NFPA 20 and NEC. The designer shall make a recommendation, which shall be submitted to the NIH for approval.

K.3.1 Generator: The preferred generator location is outdoors in a sound-attenuated enclosure with adequate working space around the generator. Consideration shall be given to diesel exhaust, feeder length, aesthetics, space requirements, ease of removal, air intakes, and so on, when locating the generator on the site. The sound-attenuated enclosure shall provide 70 to 79 dB maximum noise level 6 m from the enclosure at rated output regardless of generator size. Power and monitoring wiring shall be provided for the remote tank-level gauge. The generator enclosure shall have self-contained, batterypowered lighting on both sides of the generator(s) connected to emergency power.

The generator exhaust silencer, or muffler, shall be rated for minimum residential use or quieter to achieve the required sound rating. The location and direction of the engine exhaust shall not adversely affect air intake for the building. The preferred direction of the exhaust is up, from a sound rating standpoint. A hinged rain cap shall be provided on vertical discharge exhaust pipes.

Generators shall be ready to be exercised at the demand load or 60 percent of generator capacity, whichever is larger on a portable load bank, and per manufacturer’s recommendations.

All necessary wiring for load bank testing with proper terminal connections should be provided. A shunt-trip circuit breaker should be provided for connection to the load bank. The load-dump control circuit in the load bank shall be wired to the transfer switch(es).

If the building calls for emergency power while the generator is being exercised by the load bank, the load bank circuit breaker shall immediately open, dropping the load bank from the generator bus. An onsite minimum fuel storage capacity of 24 hours run time at 100 percent load shall be provided. Fuel-tank leak detection shall be provided.

The fuel supply line from the storage tank to the day tank shall have a hand-operated pump of the crank type, as well as an electric pump in nongravity locations. The overflow line from the engine shall be returned to the storage tank, not the day tank. In gravity situations where the main fuel tank is higher than the generator, a “reverse day tank” (return storage tank) shall pump excess fuel back to the main tank. Fuel lines shall not be routed on the surface of the floor or anywhere subject to wear or physical damage.
The generator day tank and battery charger shall be connected to emergency power. The jacket water heaters shall be connected to normal power. Where an oil circulation pump is provided to circulate oil through the engine top end, it shall be connected to normal power.

The diesel distribution system is defined as the system delivering power from the generator to the emergency terminals of the ATS. Diesel power is normally dead until the generator is on line. Normal power is delivered to the normal terminals of the ATS. Emergency power starts at the load terminals of any ATS. Diesel power is distinguished from normal power, which is live normally, and emergency power, which is live all the time except during the brief engine startup period of 5 to 10 seconds.

Where two or more ATSs will be installed, an emergency diesel distribution panel (EDDP) shall provide for future addition of ATSs with minimal interruption to the diesel power system.

The number of switched poles (three or four) in a transfer switch shall match the existing number of switched poles where replacement or upgrade is occurring. The lifting of the generator neutral to ground bond shall comply with NEC requirements for three-pole, solid neutral transfer switches. New construction or complete renovation projects shall utilize four-pole switches on three-phase, four-wire systems. The generator neutral shall be grounded when using four-pole switches in accordance with NEC requirements.

ATSs shall have override switches to cause them to transfer to the other source only if it is a good source. A “good source” is defined as one with line voltage ±10 percent available and frequency of 60 Hz ± 0.5 percent. ATSs shall have manual operator handles for safe transfer of power source external manual operator (EMOs) to mechanically operate the ATS under load. Pushbuttons shall not be used as EMOs. The EMO shall transfer the switch to any position regardless of the condition of the source. ATSs without center off-time delay shall have an in-phase band monitor. ATSs shall have center off-time delay when serving motors. ATSs shall be located indoors. If a waiver is granted for an outdoor location, the ATS shall have door-in-door NEMA Type 4X construction with strip heaters inside the enclosure. The strip heaters shall be connected to emergency power. The transfer switch shall be UL listed in accordance with UL 1008.

The ATS shall be provided with a microprocessor-controlled, complete metering package supplied on the load side of the device. These digital meters shall monitor the load whether the source is normal or diesel power. Metering shall consist, as a minimum, of a voltmeter, all three phases simultaneously; ammeter, all three phases simultaneously; frequency meter; kW meter; and PF meter plus analog bar graph for easy reading of voltage and current.

The operating mechanism of the transfer switch shall be electrically operated and mechanically held. ATSs shall not be manufactured utilizing two circuit breakers with the trip handles physically connected. The connection points of the two inputs and the load shall be in accordance with UL 1008.

Bypass transfer switches shall be used where the load cannot be taken out of service or the scheduling of an outage is extremely difficult. Transfer switches shall be maintained once per year. With a bypass switch, the transfer switch can be taken out of service with only a momentary outage to the load. The user shall be made aware of the added cost of a bypass transfer switch so as to make an educated decision. The size of a transfer switch will also increase with the addition of the bypass function. The bypass switch shall be capable of manual operation to either source, under load, regardless of the condition of the source or transfer switch position. The manual operator shall be readily and permanently accessible without opening the enclosure door.

If site constraints are such that the generator must be located indoors, the following design requirements apply:

• Provide sound-attenuated room to suit the generator being installed and the surrounding occupancies.
• The design for the volume of air delivered to the interior space where a generator is located must include the combustion air that exits the exhaust stack and the cooling air that flows through the radiator. Note that the air that flows through the engine radiator is heated, and this expanded air, if used for combustion, will reduce engine efficiency.
• The cost of conditioning the air to be used for the needs of the generator dictates that outside air be used wherever possible. This requirement has no impact on combustion air, but cooling with outside air will require that the coolant in the generator contain a chemical antifreeze ingredient.
• The outside air intake for combustion air shall be coordinated so that there is little chance that building exhaust (which might contain smoke in a fire situation) will be drawn in for combustion air.
• The ventilation air intake shall be coordinated so that it does not draw in engine exhaust.

Where the engine exhaust from the indoor generator exits the building through a wall or penetrates interior floor slabs or the roof, an insulating thimble must be used to protect adjacent materials from the excessive heat that would be created by full-load operation. The design that places a generator within a new building must also provide a suitable exit route for removal of this equipment should replacement be necessary in the future. This route shall be clearly delineated on the drawings and in the field by painted lines on the floor, walls, and so on.

The air for either cooling or combustion purposes shall be primary filtered as it enters the building from outside. The engine filter shall be considered a second and final filter for indoor units.

A duplex receptacle on the emergency system shall be placed in the corridor within 6 m of each stairwell entrance. This receptacle is primarily for the use of the NIH Fire Department in emergency situations and shall be so marked with appropriate signage so that the receptacle will not be blocked or hidden by equipment.

Corridor Receptacles: One single 20 A three-wire twist-lock receptacle (NEMA Type L5 20R) shall be installed at least as high as and 600 mm offset from the hose connection outlet to each standpipe. The receptacle shall be located in the corridor adjacent to the stairwell. Additionally, these receptacles are required at maximum 30 m intervals in long corridors. Each outlet box shall be painted fire-alarm red in color and be marked “ONLY FOR FIRE DEPARTMENT USE.”

Standpipe Receptacles: Any building requiring standpipes shall have installed one 30 A, 120 V circuit for each standpipe riser to the above-listed twist-lock receptacle. The receptacle shall be supplied from the emergency panel. The outlet box shall be painted firealarm red and be marked “ONLY FOR FIRE DEPARTMENT USE.” The wiring method for exposed work shall be RGS conduit. Boxes shall be metal, weatherproof type, with gasketed flap-door covers and threaded hubs. The wiring method for concealed work shall be conduit with appropriate galvanized boxes having gasketed flap-door covers suitable for Fire Department use.

K.3.2 Bypass Breaker: A bypass circuit breaker may be provided so that in an extended power outage the surplus generating capacity of the onsite generators can be shunted to nonemergency loads. Where a bypass breaker has been provided for this purpose, the bypass breaker must be key interlocked to prevent any possibility of normal power being connected in parallel with the local generator when normal power is restored.

K.3.3 Generator Receptacles: NIH Institutes and Centers shall review their research needs for reliability of electrical power. The use of an onsite diesel generator is a requirement for most research activities, including any programs that require animal husbandry. Where a generator is deemed necessary, generator receptacles for connection of a small NIH-owned portable generator might also be required depending on program requirements. The NIH senior electrical engineer should be consulted to determine whether a generator receptacle is required on each specific project.

Generator receptacles shall be located 1 m above finished grade at or near an accessible roadway, parking lot, or loading dock. A receptacle bank shall include the following devices:

• 200 A, 480/277 V, four-pole, five-wire Russell-Stoll junction box, angle adapter, and pin and sleeve receptacle, with either integral or separate series rated over current protective device where receptacles are parallel. The quantity of 200 A receptacles shall match the generator output.
• One Woodhead 15 A, 125 V, two-pole, three-wire NEMA Type 5-15R with a flip-lid cover for 120 V AC load bank control or battery charger.
• One Woodhead 15 A, 125 V, two-pole, two-wire-locking NEMA Type L1-15R with a fliplid cover for remote start circuit.
• One Woodhead 20 A, 250 V, two-pole, three-wire-grounding NEMA Type 6-20R with a flip-lid cover for 208 V AC heater circuit.

The last three receptacles listed above shall be installed in a Woodhead box, directly adjacent to the boxes containing the Russell-Stoll receptacles, and the wiring may be combined with the larger power conductors.

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K.4 Motor Control

Motors shall be operated on the system voltage noted in Table K.4:

Table K.4 Motor Control Rating and Voltage

Motors with ratings other than those listed shall not be connected.

Thermal manual motor starters (TMMSs) shall be of the nonautomatic resetting type and shall be lockable in the off position. Three-phase motor starters shall be sized by the NEMA rating. Motors 37,300 W and larger shall have reduced-voltage starters.

Motor starters shall be combination type with a fused disconnect or a motor circuit protector. Three-phase motor starters shall have integral single-phase protection against loss of any phase voltage. Solid-state overload relays provide this function inherently. Pilot devices to be included in three-phase motor starters are:

• Red running pilot light
• Green-power-available pilot light
• Hand-off-automatic (HOA) switch
• Control power transformer (CPT) with two primary and one secondary fuse, with secondary voltage of 120 V
• Two normally open (NO) and two normally closed (NC) auxiliary contacts with the capability of adding more
• Mechanical override to open the starter enclosure while energized

Motor control centers (MCCs) shall be provided where four or more motors are located in an area. MCCs shall have copper bus and plug-in starters with no hard wiring directly to the starter. All control wiring (in or out) shall be extended to terminal strips in a central location in the MCC in accordance with NEMA Standard ICS 2-322, Type C wiring. Motor starters shall conform to IEC 947-4-1 Type 2 component protection in the event of a shortcircuit.

Ladder diagrams and sequences of operations shall be provided for all control functions. This applies to heating, ventilating, and air conditioning (HVAC); automatic temperature controls (ATC) (pneumatic or electric); plumbing; fire protection; security; programmable lighting control; and so on.

Motor starter enclosures shall be NEMA Type 1 indoor, NEMA Type 4 outdoors, and NEMA 4X in corrosive environments. High-efficiency motors shall have the overcurrent protection sized in accordance with the manufacturer’s recommendations. See General Design Guidelines, Section: Mechanical, for variable-frequency (speed) drives (VFDs). Power factor correction capacitors shall be applied to motors 7.5 kW and larger. The capacitors shall be wired directly to the motor terminals. See Motor Disconnect Support Detail, Figure K.4, below.

Figure K.4 Motor Disconnect Support Detail

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K.5 Lighting

Lighting requirements shall follow the IESNA Lighting Handbook except as noted herein. Light levels for specific areas are listed in the Biomedical Research Laboratories and Animal Research Facilities volumes of the NIH Design Policy and Guidelines. General lighting requirements not listed in other volumes or in the General Design Guidelines, Section: Sustainable Design, will be presented here.

A lighting fixture schedule on drawings, identifying the manufacturer, catalog number, lamp type, number of lamps, fixture depth, installation method, description of fixture, and remarks should be provided.

It is highly recommended to list two additional manufacturers, with catalog number, and other information noted above for each fixture as approved equal fixtures.

K.5.1 Lamps: Fluorescent 1,200 mm lamps shall be 32 W T8 (25 mm diameter), 3 500 K color temperature with a CRI of 77, and rated average life of 20 000 hours. Compact fluorescent lamps shall be made with 13 mm diameter tubes, 2 700 K color temperature with a CRI of 82, and rated average life of 10 000 hours. The compact fluorescent lamp wattage should vary according to the application.
Compact fluorescent lamps are recommended in all but the most critical color-rendering applications. In those few specific applications, incandescent lamps may be utilized. The PAR halogen infrared (HIR) lamps are recommended for lumen output of 1 150 and lamp life of 3 000 hours.

Standard incandescent PAR and R lamps shall not be specified since they were discontinued as of October 1995. Halogen versions of the PAR and R lamps shall be submitted for the standard incandescent.

Finished rooms or spaces with 3 000 mm minimum ceilings may utilize metal halide (MH) lamps. Open fixtures shall be utilized only with metal halide lamps rated for same. Metal halide lamps shall have a color temperature of 3 200 K, rated life of 5 000 to 15 000 hours depending on the wattage, and a minimum CRI of 65. Avoid lighting fixtures with specialty lamps with less than 3 000 hours lamp life.

K.5.2 Fluorescent Lamp Ballast: Ballast shall be solid-state electronic. Ballast shall be UL listed, Class P thermal rating, and Class A sound rating per UL 935-84 and certified as follows by lighting Electronic Testing Laboratory (ETL) or UL and labeled by Certified Ballast Manufacturers Association (CBM). Ballast shall be rated for the actual number of lamps served, and the voltage shall match the connecting circuit voltage. Ballast shall have an operating frequency of 20 kHz or greater. Ballast shall contain no polychlorinated biphenyl (PCB). Light regulation shall be ±10 percent with nominal ±10 percent voltage variation. Lamps shall be operated in instant-start mode. Ballast shall be designed to withstand transients described in IEEE Standard 587, Category A. Ballast temperature rise shall not exceed 25 °C over 40 °C ambient. Ballast shall meet Federal Communications Commission (FCC) regulations, Part 18. Ballast shall have a minimum 5 year warranty. Provide variable lighting control, using continuous dimming (100 to 5 percent) and light level switching (either 100/50 percent or 100/60/30 percent).

K.5.3 Interior and Exterior Lighting: Contact the NIH senior electrical engineer for all exterior and parking structure light fixture requirements.

The following types of light sources shall be used where noted:

Table K.5.3 Light Source Type

Lighting designers shall be concerned about light pollution or the intrusion of NIH light on bordering neighbors. “House side shields” on fixtures or light fixtures with good “cut-off” optics for glare control shall be utilized near the NIH property line. The placement of lighting poles near the property line shall be avoided; however, security illumination shall be provided.

Site lighting poles shall have a 75 x 25 mm aluminum tag riveted to the pole. The tag shall clearly identify the building, panel, and circuit number where the service is derived.

Street lighting shall utilize a “Gardco CR20-3X-175MH-NP” fixture mounted 8 m above the pavement with a 175 W MH lamp. The mounting arm shall be 1.8 m long. Where poles are placed immediately at the edge of a parking lot or other areas where automobile bumpers may come in contact, the pole shall be mounted on a 1 m-high concrete base for protection. The pole shall be shortened accordingly to maintain the 8 m mounting height.

The street lighting units are generally placed 30 to 35 m apart along the majority of the twolane roads on the NIH Bethesda campus. This gives a minimum average maintained lighting level of about 50 lux on the roadway. Similarly, the walkway lighting units are spaced about 25 to 30 m apart, which gives a minimum average maintained lighting level of 10 lux. Various specific locations may require reduced spacing if they are high-accident areas or for security reasons. The A/E shall coordinate with the Project Officer for such areas.

All street lighting circuits shall be controlled at the point of origin by a photoelectric cell mounted on the side of the building where the circuit originates. A switch shall be provided to bypass the photocell so that the circuit can be energized during the day for troubleshooting purposes. Site lighting circuits shall use minimum #6 AWG wire in minimum 38 mm PVC conduit. The maximum circuit breaker size protecting site lighting circuits shall be 30 A. The plastic conduit is placed at least 600 mm below grade, and a 150 mm-wide plastic warning tape is placed above it at 150 mm below grade.

When a new street lighting pole is installed, it is required to have a 3 m-long, 19 mmdiameter, copper-clad ground rod placed in the foundation, and all metallic components shall be grounded to the rod, including metal standard, the ground wire pulled in with the power circuit, and an equipment ground wire to the luminaire.

Outdoor lighting circuits shall not have underground splices or tee splices. If splices are necessary, they shall occur only in accessible locations in light pole bases.

Walkway lighting fixtures shall be typically mounted on 3.5 m poles with 175 W MH lamps. Walkway lighting shall be “Lumec CAND2 175MH.”

Parking garages above grade with open construction shall have the perimeter fixtures controlled by a photocell. The perimeter fixtures shall be of the glare control type with a flat lens rather than the drop-lens type. Internal fixtures may have the drop lens to achieve good vertical foot-candles.

A lighting fixture schedule shall list at least two manufacturers and model numbers, preferably three.

Recessed fluorescent lighting fixtures shall be supported from the building structure on minimum two diagonal corners independent of the ceiling construction. Steel wire shall be minimum 3.5 mm.

The office average maintained light level using a maintenance factor of 75 percent shall be 500 to 800 lux. See the Biomedical Research Laboratories and Animal Research Facilities volumes for values in other types of spaces.

Circuit connections to lighting fixtures shall be made with minimum 19 mm flexible metal conduit, maximum 1.8 m in length.

Lighting fixture pendants shall be minimum 13 mm diameter stems with swivel mounts.

Industrial fluorescent lighting fixtures shall have a wire guard or plastic sleeves over the lamps. Shelf-mounted, open-strip light fixtures shall also have plastic sleeves over the lamps.

Site lighting circuit voltages of existing circuits may be obtained from the Project Officer and the NIH Electric Shop.

Animal loading docks and food service loading docks shall use HPS lighting. Loading docks shall be provided with 120 V source(s) for bug “zapper” fixtures.

The zonal cavity method shall be used for calculating the design light levels for uniform layouts with standard light fixtures. The point-by-point method shall be used for calculating the design light levels for unique lighting fixture applications or where asymmetrical lighting layout is utilized. All fluorescent lighting fixtures in mechanical areas shall have wire guards or lens covers.

Storage areas and mechanical equipment areas with high ceilings shall use fluorescent or HID lamps depending on the size of the area and height of the ceiling. Incandescent lighting shall not be used except when approved by the NIH. Where contactors are used, they shall be mechanically held.

Where HID fixtures are used for interior illumination, all fixtures shall be equipped with instant restrike ballast.

Exterior lighting shall be controlled by a digital time clock and photoelectric controls and have a hand-off-auto switch. Wiring for lighting in large outdoor areas shall use multiphase branch circuits, and adjacent fixtures shall be alternately connected to different phases.

The protective circuit breakers shall be single-phase to preclude a total outage of light in any one area. Pole-mounted lighting fixtures and interior pole wiring shall be protected by in-line fuseholders located within the pole base or transformer housing.

K.5.4 Emergency Lighting: Emergency lighting and exit sign fixtures shall be fed from the emergency circuits where available or shall have battery backup power. Battery ballast shall have an integral self-test feature. All emergency battery powered lights shall have a test button and battery condition indicator light. Exit signs shall be LED type.

K.5.5 Light Poles: The maximum height for parking and roadway lighting should be 8 m. Roadway lighting poles shall have breakaway bases; poles for parking lots shall be protected by poured concrete bases.

All light poles shall be grounded and have adjusting leveling nuts. Mounting bolts and adjusting leveling nuts shall have trim cover.

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K.6 Power Quality

K.6.1 Grounding: A solid-grounding electrode system shall be provided to ground the service entrance equipment. Where a pad-mounted transformer is utilized, a ground ring of #4/0 AWG bare copper conductors shall be provided around the transformer pad. Ground rods shall be placed approximately 1 m outside each corner of the pad. Two #4/0 AWG conductors shall be brought up into the transformer enclosure for equipment grounding. The transformer neutral shall be grounded only inside the service entrance (SE) equipment in the building. A #4/0 AWG ground conductor shall extend from the outdoor ground ring underground to the main electric room ground bus.

A similar ground ring shall be installed surrounding the main electric room (or indoor transformer vault) with ground rods in each corner and maximum 6 m on center around the perimeter of the room. Ground conductors shall be connected to a wall-mounted ground bus at each end of the bus and at each ground rod between.

The ground bus shall be 50 x 6 mm copper and extend the length of one of the long walls of the transformer vault. The ground bus shall be mounted 300 mm above finished floor. Ground conductors leading to the ground ring shall be exothermically welded to the ground bus; all others shall be bolted. Equipment and grounding electrode conductors (all bolted conductors) shall be labeled. Labeling shall utilize embossed brass metal tags with nylon tie wraps.

Ground conductors brought through the floor or walls shall be in PVC conduit sleeves. Ground conductors shall not be located in traffic areas or where subject to damage. However, where ground leads through the floor are subject to damage due to layout changes, the PVC sleeve shall be cut off flush with the floor. A steel “C” channel shall be placed face down over the penetration to form a protective bridge. The “C” channel shall be bolted to the floor with the ground wire exiting one end. Feeders and branch circuits shall contain equipment ground conductors sized in accordance with the NEC.

Panelboards serving isolated ground receptacles shall have an isolated ground bus in addition to the equipment ground bus. The isolated ground bus shall not be bonded to the panelboard enclosure or equipment ground bus. Isolated ground receptacles are typically required in laboratories and offices. The buses shall be clearly labeled. An isolated ground conductor shall be sized to match the phase conductor. The isolated ground conductor shall be isolated to the separately derived power source.

All structural steel shall be grounded. All exposed metallic structures such as light poles, aerial structures, and manhole/handhole covers shall be bonded to the grounding conductor and grounded to separate grounding electrodes. Fence enclosures around or adjacent to substations shall be grounded to electrodes with flexible braid at 15 m intervals, with bonding jumpers at gates and fence openings to provide metallic continuity. All grounding test points shall be accessible for verification.

A copper ground bus mounted 600 mm above finished floor and mounted on insulators 40 mm from the wall shall be provided as follows:

• Main electric room: 6 x 50 mm bus installed on one long access wall.
• Electrical closets/rooms: 6 mm x 50 mm x 600 mm bus connected to the main electric room with a #4/0 bare copper ground wire. A #4/0 bare copper ground riser from each closet ground bus vertically routed through stacked electric rooms shall provide grounding connection between the closets.
• Main communication room: 6 mm x 50 mm x 600 mm bus connected to the main electric room ground bus with a #2/0 insulated grounding conductor
• Communication closets/rooms: 6 mm x 50 mm x 600 mm bus connected to the main communication room with a #2/0 bare copper ground wire. A #2/0 bare copper ground riser from each closet ground bus vertically routed through stacked communication rooms shall provide grounding connection between the closets.
• A separate grounding conductor shall be provided for all electrical work. The ground conductor shall be insulated, color-coded green, and sized per NEC requirements.
• A #4/0 ground conductor shall be provided in all medium-voltage ductbanks.
• All underground connections shall be made using exothermic weld connectors and installed utilizing the appropriate tool as recommended by the manufacturer.

K.6.2 Harmonics: The power supplies found in any computerized equipment such as PCs, laser printers, file servers, electronic ballasts, VSDs, and uninterruptible power supplies impose third-order (180 Hz) and higher harmonic currents on the neutral conductor of threephase, four-wire electrical systems. The triplet (multiples of three) harmonics add in the neutral conductor. The worst-case 100 percent total harmonic distortion would create a
neutral current of 1.73 times the phase current.

Where a high concentration of computer loads relative to all other noncomputer loads is anticipated, precautionary measures shall be taken. The following shall be provided where a large percentage (60 percent or more) of the load is or will be computerized:

• Full-size individual neutrals in branch circuits.
• Branch circuit panel boards with 200 percent neutrals.
• Transformers with K rating of K-13 and 200 percent neutral from transformer to panel.
• Adequate cooling in electrical rooms.
• Separate dedicated circuits for printers and PCs.
• In extreme cases where two high harmonic loads are approximately equal, a phaseshifting transformer will shift the current of one load (feeder) relative to the other such that the harmonic currents cancel. This type of transformer is typically used to fix an existing problem and is difficult to apply during design unless specific information is known about the load.

K.6.3 Transients: The NIH has not experienced many problems with transients to date. Therefore, at this time no specific requirement for transient-voltage surge suppression (TVSS) is made. However, if the user has very sensitive electronic equipment without UPS protection, TVSS protection may be prudent. A layered protection plan is recommended. ANSI/IEEE Standard C62.41 Category C3 TVSS protection shall be provided at the SE and Category B3 TVSS protection at the downstream branch circuit panel. When lightning protection is deemed necessary, TVSS at the main service entrance switchgear shall be provided.

K.6.4 Lightning Protection: New buildings at the NIH shall be evaluated for lightning protection based on the guidance provided by the latest NFPA Standard 780, Lightning Protection Code.

Lightning protection will be required where the NFPA 780 study indicates a moderate or higher risk. Lightning protection systems shall meet the most restrictive requirements of the following:

• NFPA 780
• LPI-175
• UL

Low buildings may be protected by the lightning protection installed on an adjacent higher building. The above-listed standards show the zone of protection.

New buildings that need lightning protection shall receive a Master C Label from UL after the new lightning protection system is evaluated by UL and found to be acceptable. The UL label confirms that the whole structure, including all roof levels and terraces, is protected against lightning strikes.

As existing buildings are altered or modified, especially when the outer envelope is changed, the lightning protection system shall be updated and the protection verified. The vehicle for this is a UL Letter of Finding, rather than a review of the entire building. If a whole building review is required, then a new Master C Label is issued, termed a “Reconditioned Master Label.”

When a lightning protection system is to be installed on a new building, a ground girdle shall be provided encircling the entire building. All metallic objects such as pipes and conduits crossing the ground girdle shall be bonded to the ground girdle.

All electrical service entrance, generator, telecom, and LAN grounding systems shall be grounded to the lightning protection system.

Lightning protection conductors shall be installed in nonmetallic conduit if routed inside buildings. On temporary buildings and minor additions, the A/E shall determine the necessity of lightning protection modifications.

Properly sized surge protectors shall protect all medium-voltage transformers, mediumvoltage motors, medium-voltage distribution cables, and telephone and computer equipment.