46 C.F.R. § 111.05-31
Grounding conductors for systems.
Cite as 46 C.F.R. § 111.05-31 (2026)
(a) A conductor for grounding a direct-current system must be the larger of:
(1) The largest conductor supplying the system; or
(2) No. 8 AWG (8.4mm
2
).
(b) A conductor for grounding the neutral of an alternating-current system must meet Table 111.05-31(b).
Table 111.05-31(
b
)—Neutral Grounding Conductor for Alternating-Current System
Size of the largest generator cable or equivalent for parallel generators—AWG-MCM (mm
2
)
Size of the system grounding conductor—AWG(mm
2
)
Greater than
Less than or equal to
2 (33.6)
8 (8.4)
2 (33.6)
0 (53.5)
6 (13.3)
0 (53.5)
3/0 (85.0)
4 (21.2)
3/0 (85.0)
350 MCM (177)
2 (33.6)
350 MCM (177)
600 MCM (304)
0 (53.5)
600 MCM (304)
1100 MCM (557)
2/0 (67.5)
1100 MCM (557)
3/0 (85.0)