Another Sub-Panel Question

[Sam65]

New here and I've read some of the threads on this issue but still unclear. Here is my situation, I’m trying to run 240 volts to a detached shop/garage about 100’ away. I would like at least a 100 amp sub panel with more than 6 circuits. I have a 200 amp service back of home and have space for a 100 amp circuit breaker. My question is if I use #2 copper THHN can I install 100 amp circuit breaker at the main and use a 125 amp sub panel with a 125 amp main breaker. From what I understand is the #2 feeder circuit would be protected by 100 amp breaker and the 125 amp would only serve as a main disconnect for the shop. Also thought about using 2-2-2-4 SER aluminum conductors but with a 90 amp breaker at the main and 125 main sub panel. But that is out the window as I read that 2-2-2-4 SER cable cannot be installed in conduit below ground, is that true? Any other suggestions?

Thanks

 

[pattenp]

Use individual aluminum or copper THHN/THWN wires in conduit. If you use aluminum 2-2-2-4 Mobile Home Feeder it's good to 90 amps. As you foundout, SER can't go below ground in conduit.

Oh.. forgot... the #2 copper is fine with a 100A breaker in the main panel with using a 125A main beaker panel as the sub-panel. #1 aluminum will work for 100A too, but #1/0 would be better.

 

[PetesPonies]

+1 I agree

 

[Charles (in GA)]

PROPERLY MARKED 2-2-2-4 Mobile Home Feeder can go in conduit and underground. Needs to be marked RHH, RHW in addition to the USE-2 marking.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet7

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet15

 

[ishiboo]

PROPERLY MARKED 2-2-2-4 Mobile Home Feeder can go in conduit and underground. Needs to be marked RHH, RHW in addition to the USE-2 marking.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet7

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet15

Is there copper MHF? If not, AL #2 is only good for 90A on a sub if we are keeping things legal. I have no issues breakering it at 100A though.

 

[ezzzzzzz]

It's a one time shot. Use the more expensive copper for capacity and ease of installation. Aluminum, even in individual conduit form, ***** pulling around bends even with lubricant.

 

[pattenp]

Just to clarify.... Mobile Home Feeder (MHF) is a direct bury cable and has USE-2/RHH/RHW-2 ratings. The RHH/RHW-2 is needed if the cable is to be run inside of the structure. URD is another direct bury cable but only carries the USE-2 rating and is to be used only outside the structure. When the MHF is run inside is has to be in conduit.

PROPERLY MARKED 2-2-2-4 Mobile Home Feeder can go in conduit and underground. Needs to be marked RHH, RHW in addition to the USE-2 marking.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet7

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet15

 

[pattenp]

Not that I know of.

Is there copper MHF? ............

 

[Sam65]

Okay I decided to use 1/0 aluminum THHN/THWN wire in conduit. What size of ground do I need to run?

 

[PetesPonies]

I used #4

 

[hidollartoys]

For 100 amps, #8 copper or #6 aluminum