NEC Table 250.66 is used for sizing grounding electrode conductors for alternating current systems. As defined in Article 100, the Grounding Electrode Conductor is used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system .

TABLE 250.66 Grounding Electrode Conductor for Alternating-Current Systems Size of Largest Ungrounded Service-Entrance Conductor or Equivalent Area for Parallel Conductors" (AWG/kcmil) Size of Grounding Electrode Conductor (AWG/kcmi1) Aluminum or Copper-Clad Copper Aluminumb Copper 2 or smaller (50mm2) or I/O 2/0 or 3/0 Over 3/0 through

A grounding electrode conductor (GEC) from an electrical service to a ground rod, pipe or plate type electrode is never required to be larger than 6 AWG copper or 4 AWG aluminum unless the GEC continues on from the rod, pipe or plate to connect another electrode that may require a larger GEC such as a concrete encased electrode, building steel ...

The size of the grounding electrode conductor and bonding jumper (s) for connection of grounding electrodes shall not be smaller than given in Table 250.66, except as permitted in 250.66 (A) through (C).

An equipment grounding conductor (EGC) is sized differently than a grounding electrode conductor (GEC). EGC’s are sized from Table 250.122 based on the size of the overcurrent device ahead of the circuit. The GEC is sized from Table 250.66 based on the size of the ungrounded service entrance conductors.

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2017年5月22日 · To answer your question, see note 1 to Table 250.66, and you'll need to use Table 8. But, there is table 250.66 and section 250.66 for sizing GEC. The size of the GEC depends on what the GE is.

Table 250.102(C)(1) is used to size the grounded conductor, main bonding jumper, system bonding jumper, and supply-side bonding jumper for alternating-current systems. Keep in mind that this table is for sizing grounded conductors and the bonding jumpers listed, NOT for sizing grounding electrode conductors, which must be done using Table 250.66.

Where the overcurrent device is an instantaneous-trip circuit breaker or a motor short circuit protector, the equipment grounding conductor (EGC) shall be sized from Table 250.122 using the maximum permitted rating of a dual element time-delay fuse selected for branch-circuit short-circuit and ground-fault protection in accordance with 430.52(C ...

2014年7月26日 · In the NEC, there appears to be two tables that contradict each other in regard to the minimum sized equipment grounding conductor. In Table 250.66, it lists a 4 AWG copper grounding conductor for 2/0 copper or 4/0 aluminum service conductors, which are the sizes used for 200A services.