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 350 (185mm2) Over 350 through 600 (300mm2) Over 600 ...

Table 250.122 — Grounding Conductor Size Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment

conductors can also be phase conductors in certain applications. Grounding Conductor, Equipment (EGC) — The conductive path(s) that provides a ground-fault current path and connects normally non-current-carrying metal parts of equipment together and to the system gro. nded conductor or to the grounding electrode conductor, or both.

2021年3月2日 · The GEC is sized according to the largest ungrounded (hot) service conductors that feed the service, per NEC Table 250.66. Three Big Changes for Sizing EGCs in the 2020 NEC

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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 ...

Find the EGC for three 3-phase circuits in the same raceway, protected by overcurrent devices rated 30, 60, and 100 amperes. The three circuits would require only one equipment grounding conductor, sized according to the largest overcurrent device (in this case, 100 amperes).

2020年6月25日 · One set of secondary conductor #3/0 AWG goes to 200A MCB panelboard from the transformer, second set of secondary conductor #2 AWG goes to 100A MCB from the transformer. Both panels within 10 feet of each other. 1. Transformer grounding electrode conductor size should be based on #3/0 or #2 AWG or combination sum of #3/0 and #2 AWG? 2.

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).