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I have a shed 50 feet from my main house. I need to have two circuits there - 1x240v and 1x120v to power some outlets and lights. The 240v circuit will be 30amps at max load. The 120v circuit is just standard 15amp. So 45amps max for the whole thing.

I was told I should run a feeder out to a sub-panel at the shed, and install a grounding rod.

Is that the only/correct way to do it?

In practice, how would this look?

Let's assume the total max amperage of the 240v and 120v circuits at the shed will be 45 amps. Distance 50 feet. Do I then put a 60amp breaker on my main panel as the feeder breaker, run a 4 AWG feeder through conduit buried underground to the shed sub-panel? Then separate breakers (1x40) and (1x15) at the sub panel for the 240v circuit and the 120v circuit, with everything grounded to the grounding rod?

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  • I hear that 2-2-2-2 AL feeder is the cheapest, check local pricing. It is good for 90 amps, so will not need upgrading the future. Do not need bigger breaker for bigger wire or for bigger sub panel in the shed.
    – crip659
    Commented Jul 13, 2023 at 22:12
  • The breaker you use will determine the smallest wire gauge you can use, larger gauges are always allowed(within limits). You do not know the future, so do not not limit yourself with a small panel. If a 200 amp panel is only a few bucks/dollars/something more, do not be afraid to use/buy it.
    – crip659
    Commented Jul 13, 2023 at 23:00
  • Is there a downside to using 2-2-2-4? I assume 4 is the ground?
    – Ilya Mirk
    Commented Jul 13, 2023 at 23:40
  • Besides using different languages(NSFW) when trying to bend it to fit into a connection, not much, but you will have the same problem with most heavy wire, so get the cheapest.
    – crip659
    Commented Jul 13, 2023 at 23:58

1 Answer 1

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Since the two circuits are different voltages, you have the option of simply running two circuits. However that will paint you into the corner for any future expansion, and may cost more in pricey copper than running an aluminum heavy feeder (fine, really!) etc. So I would call it unwise.

I would recommend pretty much as you describe, using typically #2 aluminum is your best value for amps, a 60A breaker since it's the cheapest breaker that will take #2, and breakers as you say.

Feeder needs to be 4-wire, carrying ground separate from neutral, and the ground rods are still required.

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