§ 111.05-31 - Grounding conductors for systems.  


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  • § 111.05-31 Grounding conductors for systems.

    (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 (8.4mm2).

    (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 (mm2) Size of the system grounding conductor - AWG(mm2)
    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)