Sub panel install

[codeman021]

Hello, I have been reading over the posts here and searching for answers but im a bit confused.

What I want to do is install a 100 amp breaker in my main panel run wire to a sub panel in my shed with circuits for outlets/ lights and my compressor.

what is the best way to do this?

I have 1 1/2 conduit buried already

 

[rockwithjason]

umm, you pull wire in the pipe and make up the panels?

 

[codeman021]

Right I figured that much. What I was wondering if it was good to run a sub panel off of a breaker in the main panel. 100 amp main to a 100 amp sub.

 

[EOC_Jason]

Yes, it is perfectly acceptable (and common) to do that....

I would recommend having a ground rod at the sub panel though, just to be safe.

 

[rockwithjason]

you must have a ground rod at the shed in almost every circumstance. you must also have a method to disconnect all ungrounded conductors at the shed such as a main breaker or a disconnect switch. you can use a 100 amp rated panel and feed it from a 50 amp breaker but you cannot use a 100 amp breaker to feed the sub panel.

 

[pattenp]

Actually you should have two ground rods at the shed. You only need a main disconnect if the sub-panel has more than 6 breakers. So you can use a main lug panel as long as you don't have more than six breakers to turn off to kill the power to the circuits. The best thing to do is to use a main breaker panel for the sub-panel.

 

[pattenp]

Do you care to reword this comment?

you must have a ground rod at the shed in almost every circumstance. you must also have a method to disconnect all ungrounded conductors at the shed such as a main breaker or a disconnect switch. you can use a 100 amp rated panel and feed it from a 50 amp breaker but you cannot use a 100 amp breaker to feed the sub panel.

 

[codeman021]

OK perfect so what im going to do is install 100 amp breaker in the main panel to a main lug sub panel, using 3 gauge wire 2 hot 1 neutral and 1 ground then pound in two ground rods 6 feet apart, hook that to the ground bar on the sub. I will not have more than six breakers.
Sound good?

 

[pattenp]

Yeah.. but if I were you I'd use a main breaker panel for the sub. It cost not much more than a main lug and gives you flexibility.

 

[codeman021]

Perfect thank you guys for your help, I am ready to tackle it now.

 

[EOC_Jason]

Why two ground rods? Is that a local code thing?

 

[Norcal]

Why two ground rods? Is that a local code thing?

No, it's a NEC requirement unless you can prove you have 25 Ohms of resistance or less, since the equipment is expensive it's cheaper to drive the 2nd rod & be done with it.

 

[Jefe]

FWIW, my AHJ told me that one ground rod was sufficient. He said something to the effect of "if we were on a newer NEC you'd need two."

 

[EOC_Jason]

Yeah everything here in Houston is just one ground rod per breaker box for 200A service (or less)... If you get 320A or higher then you need a ground rod next to the meter can / disconnect setup. Maybe because we have such a high water table and the rainfall? I can see in drier or rockier areas where you might not get as good of a ground but seriously if someone said "You need a second ground rod in that setup" around here you would probably get laughed at.