30 CFR § 75.601-3
Short circuit protection; dual element fuses; current ratings; maximum values.
Dual element fuses having adequate current-interrupting capacity shall meet
the requirements for short circuit protection of trailing cables as provided
in §75.601, however, the current ratings of such
devices shall not exceed the maximum values specified in this section:
---------------------+------------------+------------------
| Single conductor | Two conductor
| cable | cable
Conductor size (AWG |---------|----------|---------|----------
or MGM) | | Max. | | Max.
| Ampa- | fuse | Ampa- | fuse
| city | rating | city | rating
---------------------+--------+---------+--------+---------
14..................|........|.........| 15 | 15
12..................|........|.........| 20 | 20
10..................|........|.........| 25 | 25
8...................| 60 | 60 | 50 | 50
6...................| 85 | 90 | 65 | 70
4...................| 110 | 110 | 90 | 90
3...................| 130 | 150 | 105 | 110
2...................| 150 | 150 | 120 | 125
1...................| 170 | 175 | 140 | 150
1/0.................| 200 | 200 | 170 | 175
2/0.................| 235 | 250 | 195 | 200
3/0.................| 275 | 300 | 225 | 225
4/0.................| 315 | 350 | 260 | 300
250.................| 350 | 350 | 285 | 300
300.................| 395 | 400 | 310 | 350
350.................| 445 | 450 | 335 | 350
400.................| 480 | 500 | 360 | 400
450.................| 515 | 600 | 385 | 400
500.................| 545 | 600 | 415 | 450
---------------------+--------+---------+--------+---------