Wiring a subpanel question

[BareBones]

I want to put a new panel in my garage 125A with 8 open slots. Currently there is a 30A with 2 slots. Also it's wired form the main box(in my house) with 8 ga to a junction box(just before it goes outside) where it turns into 12ga 3 conductor Romex. Then it runs to my garage 30A panel.

Basically I want to know if the 12 Ga Romex is big enough to handle a larger box. I'm thinking no because 12 ga is only supposed to hand 20 amps and my total garage load at times will exceed that.

So if that's true what gauge would be good? #2?

Bob

 

[dipper]

no, you need bigger wire. I ran 4awg copper for my 100amp subpanel; that is the minimum. You need 4 wires (hot-hot-neutral-ground) and the neutral and ground are kept separate in the subpanel. You can do alot of it yourself depending on your abilities but you should have it inspected.

 

[Aceman]

I ran 4awg copper for my 100amp subpanel; that is the minimum.

No, that is still smaller than the minimum. I know I've mentioned it to you before but just because you can get away with it doesn't mean everyone else can. The best way is to start with the code minimum and if their local jurisdiction has an exception to this allowing a smaller wire, then reduce the size if they so choose too.

no, you need bigger wire.

Hey, we agree.

To the OP: What size subpanel are you wanting and how far is the run to the garage?

 

[BareBones]

Its a detached garage, the run could be either underground or above ground, it's currently underground. It currently starts with a 30 amp breaker at the main panel. I didn't think 10 or 12 would be good enough but I wanted to make sure. Should I change the breaker at the main panel also?
There is no phone,water, or cable only gas for my furnace.

Bob

 

[BareBones]

Thanks that explains a lot. What should I do with the main panel and the 30 amp breaker that starts the run to the garage.

 

[ddawg16]

Quick side question (not trying to hijack the thread)...

Can the ground wire, #8, be bare copper? It was my understanding the ground does not have to be insulated running inside the conduit.