Sub Panel for Shop

[Shawn Siegrist]

My brother in law needs to run a subpanel for his shop, he will need to following circuits:

1 20A / 220V
1 20A / 110V
1 15A / 110V

What size breaker for the subpanel and what gage AL or CU wire should we run?


Thanks for the help,
Shawn

[Rob Russell]

Based on the circuits you're listing, you need at least a 40A/240v subpanel.

I'd put in a larger one to allow room for growth. Assuming this is a wood working shop, the 240v circuits tells me something like table saw or band saw. That's fine, but I'd want room for a 240v duct collector or 240v compressor and those should be on separate circuits.

A 60A panel should be fine.

In terms of conductor size, you need #6 copper or #4 aluminum. Those are rated for 55 amps, but that's not a standard breaker size so you can round up to the next standard size of 60 amps.

I would use 2-2-2-4 aluminum SER. It's commonly carried at the big box stores and is cheaper than 6-3 copper NM. The 2-2-2-4 SER is also rated for 75 amps in case you ever needed that much juice. The cost at our local HD is $2.33/foot for the 6-3 copper NM cable and $1.49/foot for the 2-2-2-4 aluminum SER.

[Shawn Siegrist]

Thank you so much, you covered everything and then some!

[Rollie Meyers]

One thing that must be considered is if the lugs of the circuit breaker suppying the panel will accept the larger size wire, snipping strands to make it fit is not a acceptable method, be sure to check that out before proceeding. A 60A breaker may not handle # 2 AWG but a 70A should.