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
---------------------+--------+---------+--------+---------
