[Code of Federal Regulations]

[Title 46, Volume 4]

[Revised as of October 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 46CFR111.70-7]



[Page 236]

 

                            TITLE 46_SHIPPING



                  (This book contains parts 90 to 139)

 

   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)

 

PART 111_ELECTRIC SYSTEMS_GENERAL REQUIREMENTS--Table of Contents

 

       Subpart 111.70_Motor Circuits, Controllers, and Protection

 

Sec.  111.70-7  Remote control, interlock, and indicator circuits.



    (a) Overcurrent protection. A conductor of a control, interlock, or 

indicator circuit of a motor controller must be protected against 

overcurrent unless:

    (1) The conductor is wholly within the controller enclosure;

    (2) The rating or setting of the branch circuit overcurrent device 

is not more than 300 percent of the current-carrying capacity of the 

control, interlock, or indicator circuit conductor;

    (3) There is an overcurrent device in each side of the line that has 

a rating or setting of not more than 300 percent of the current-carrying 

capacity of the control, electrical interlock, or indicator circuit 

conductor, except if under operating conditions there is no appreciable 

difference in potential between the external conductors, overcurrent 

protection need only be at the supply of that side of the line; or

    (4) The opening of the control, interlock, or indicator circuit 

creates a hazard.

    Note: For overcurrent protection of steering gear control and 

indicator circuits, see Subpart 111.93 of this chapter.

    (b) Accidental ground. The controller must be designed to prevent an 

accidental ground in a remote control circuit from causing the stop 

switches to fail to operate or causing the motor to start.

    (c) Source of potential. The potential for a control, interlock, or 

indicator circuit must be derived from the load side of the motor and 

controller disconnect device, except if the control functions require 

circuits that must be common to two or more controllers, the switching 

arrangement in paragraph (d) of this section must be met.

    (d) Switching. In the design of a control, interlock, or indicator 

circuit, all practicable steps must be taken to eliminate all but one 

source of power in an enclosure. If the control functions make it 

impracticable to energize a control interlock or indicator circuit from 

the load side of a motor and controller disconnect device and the 

voltage of the control, interlock, or indicator circuit is more than 24 

volts, there must be one of the following alternative methods of 

switching:

    (1) Each conductor of a control, interlock, or indicator circuit 

must be disconnected from all sources of potential by a disconnect 

device independent of the motor and controller disconnect device. The 

two independent devices must be adjacent to each other, and a fixed 

sign, warning the operator to open both devices to disconnect completely 

the motor and controller, must be on the exterior of the door of the 

main disconnect device.

    (2) Each conductor of a control, interlock, or indicator circuit 

must be disconnected from all sources of power by a disconnect device 

actuated by the opening of the controller door, or the power must first 

be disconnected to allow opening of the door. The disconnect device and 

its connections, including each terminal block for terminating the 

vessel's wiring, must have no electrically uninsulated or unshielded 

surface. When this type of disconnect device is used for vital auxiliary 

circuits, a nameplate must be affixed to the vital auxiliary motor 

controller door that warns that opening the door will trip a vital 

auxiliary off-line.



[CGD 74-125A, 47 FR 15236, Apr. 8, 1982, as amended by CGD 94-108, 61 FR 

28282, June 4, 1996; 62 FR 23909, May 1, 1997]