(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--
Less than or AWG(mm\2\)
Greater than 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)------------------------------------------------------------------------