[georgemcq]

I am looking to install a 100amp sub panel in an out building (garage / barn) about 60 feet from house. Will use 3 - #2 cu with #4 ground thru 2" PVC conduit.


Do I need 2 ground rods at out building sub panel?


Thanks so much for the assist.

 

[rjniles]

Yes 2 ground rods required

 

[Sparkyb60]

Yes, 2 ground rods . Don't forget to buy a ground bar to separate the neutral from the grounds. Main disconnect also required.

 

[seharper]

Usually you handle the "main disconnect" by getting a panel with a main breaker.

Remember: You're allowed to get a panel which is *greater* than 100A. There is nothing wrong with that. It's like getting 130 mph tires instead of 85 mph tires, probably a good idea if you actually do drive 85 mph

Also, everybody goes "I just need a few spaces." Then later they go "my panel is full". Spaces are dirt cheap *before* you buy the panel... so I recommend going ape-crazy. A 30-space subpanel for a 100A feed to a shop is not excessive. It's a tiny part of overall project cost, and it makes sure you're not painted into a corner later.

The trope is the novice who proudly scrimps on the panel whilst insisting on very expensive copper wire for the cable run. Saves $20, wastes $300, then runs out of spaces. Aluminum is a good choice for feeder. #1 Al is perfectly fine for a 100A panel, unless your distance is excessive, then 1/0. Price it out... you'll like it.

 

[georgemcq]

I am looking at Square D 100 amp main breaker panels with 30 spaces. Just have not decided whether to mount panel inside or outside of metal building. Will also bond the building and support steel.


Thanks for the replies.

 

[rjniles]

I am looking at Square D 100 amp main breaker panels with 30 spaces. Just have not decided whether to mount panel inside or outside of metal building. Will also bond the building and support steel.


Thanks for the replies.

Outside panel must be rated for that use and it will restrict your wiring methods. NM cable cannot be used outside.

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[JoeSims]

One more option if you will have a concrete foundation, is to tie the ground wire to rebar in the concrete. I went 10 feet horizontal rebar in the footer before coming up. Then bent it and had it sticking out of the footer into the wall cavity below the electric box. I then used an acorn nut to tie a #6 ground wire to it. Worked good for my application