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250.122 Sizing Equipment Grounding (Bonding) Conductor.

(A) General. The equipment grounding (bonding) conductor must be sized in accordance with Table 250.122, based on the ampere rating of the circuit-protection device, but in no case is it required to be larger than the circuit conductors. Figure 250–169

Author’s Comment: Equipment grounding (bonding) conductors must be capable of safely conducting any ground-fault current likely to be imposed on them [110.10]. If the equipment grounding (bonding) conductor isn’t sized to withstand the ground-fault current, the conductor may burn clear before the protective device responds.

Table 250.122—Minimum Size Equipment Grounding (Bonding) Conductor

Protection Rating.......CopperConductor

15A..........................14 AWG
20A...........................12 AWG
30—60A..................10 AWG
70—100A..................8 AWG
110—200A................6 AWG
225—300A................4 AWG
350—400A................3 AWG
450—500A................2 AWG
600A...........................1 AWG
700—800A.............1/0 AWG
1,000A.....................2/0 AWG
1,200A.....................3/0 AWG

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Figure 250–169
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