What is the minimum size copper equipment grounding conductor required for a 20-ampere lighting circuit?

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Multiple Choice

What is the minimum size copper equipment grounding conductor required for a 20-ampere lighting circuit?

Explanation:
The key idea is that the equipment grounding conductor (EGC) size is determined by the rating of the overcurrent device protecting the circuit. The EGC provides a low-impedance path for fault current so the protective device trips quickly, protecting people and equipment. For a lighting circuit protected at 20 amperes, the minimum size copper EGC required is 12 AWG. This size strikes the balance between providing a reliable fault path and not being larger than necessary. Using a smaller conductor, like 14 AWG, could have enough impedance to delay tripping in a fault, which is why the minimum is raised to 12 AWG. Larger sizes, such as 10 AWG or 8 AWG, would also be acceptable, but they’re not the minimum required.

The key idea is that the equipment grounding conductor (EGC) size is determined by the rating of the overcurrent device protecting the circuit. The EGC provides a low-impedance path for fault current so the protective device trips quickly, protecting people and equipment.

For a lighting circuit protected at 20 amperes, the minimum size copper EGC required is 12 AWG. This size strikes the balance between providing a reliable fault path and not being larger than necessary. Using a smaller conductor, like 14 AWG, could have enough impedance to delay tripping in a fault, which is why the minimum is raised to 12 AWG. Larger sizes, such as 10 AWG or 8 AWG, would also be acceptable, but they’re not the minimum required.

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