SEC's Different Sizes

Good afternoon all. I inspected a home built in 1978 yesterday and the 100 AMP Eaton main panel looked fairly new. The two hot SEC’s were #2 AL and the neutral SEC was #4 AL. I wrote it up as a deficiency that the neutral SEC is undersized. The SEC’s should all be the same size, correct?

The neutral is sometimes one size smaller.

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10-4. So in a 100 AMP Panel a #4 AWG Aluminum Neutral SEC is acceptable?

Wow, you read that link already?

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Thank you for sharing. Understood now.

For services, the neutral is sized to carry the maximum unbalanced current (white) or the minimum size for a fault

A neutral for a service can be downsized as small as the grounding electrode conductor if the load calculates that low,

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Thats correct. You need to bring the neutral to the service disconnect even if you will not be using it for any loads. The minimum size would be the same as the GEC for a water pipe electrode.


Makes perfect sense. Thank you guys for clarifying.

You lost me there.