I am wanting to put a 100 amp sub panel in a garage, I want to run it from the main in the house (which is 200 amp) about 80 to 85 feet away there is only 20 amp running to the garage now with no junction box or sub panel, what size wire do I need also, the garage is covered in metal siding do I need to do anything special with the siding

Most areas would allow the use of #4cu or #2al for a 100a sub-feed.
If they do not, use either of those sizes and just use a 90a breaker.

The siding does not have to be bonded, but it is not a bad idea.
Is the framing metal? That would have to be bonded.

The NEC requires structural metal to be bonded, if likely to become energized, but no mention of metal siding. Yet, it doesn't hurt to check with the authority having jurisdiction. I know my inspector wanted me to bond the metal siding on a garage we wired. Yet, the NE code does not call for this.

-Are you planning to run your conductors underground?
-Copper or Alum?

I guess I took waay to long to type... :)

Man, it took you seven minutes to type that? :p :D

Man, it took you seven minutes to type that? :p :D
- 1 min to type
- 1 min to get my code book
- 4 minutes to find the code refer
- 30 secs to let my dog out
- 30 secs to get back to my computer

:D

I bet there was a pee break in there somewhere too. :D




- 4 minutes to find the code refer
If we ever meet I'll have to bring you an NEC on CD.
Best thing since the cordless drill! :cool:

I bet there was a pee break in there somewhere too. :D



If we ever meet I'll have to bring you an NEC on CD.
Best thing since the cordless drill! :cool:

I have it! ;)

Most areas would allow the use of #4cu or #2al for a 100a sub-feed.
If they do not, use either of those sizes and just use a 90a breaker.

The siding does not have to be bonded, but it is not a bad idea.
Is the framing metal? That would have to be bonded.


Thanks for the response, It is just metal siding. On an old two story barn, I am wanting to have a wood shop upstairs on the second story, would it be even better to have a regular main instead of a subpanel

would it be even better to have a regular main instead of a subpanelPlease explain what you mean by this.

Do you mean a dedicated service to the barn?


Just so you know, a detached structure fed from another building does require a main disconnect.

Please explain what you mean by this.

Do you mean a dedicated service to the barn?


Just so you know, a detached structure fed from another building does require a main disconnect.


Yes I mean a dedicated service to the barn, would that be better than a sub panel, and can it come from the same source as the house service

"Better" in this case is a subjective thing. Do you need or want it separate?

Your POCO can tell you where it can come from. It is doubtful that it can come from the house itself.