New Load Center for My New Workshop

[u2jimbo]

Hi Guys:

This is my first post - be gentle...

I am about to start wiring three 240v circuits in my new garage shop. The house main electrical panel has a 100 amp circuit breaker with 2/0 awg aluminum conductors running to an external, main lug load center mounted on an outside wall of my garage. Inside this box are two breakers. One is a 240v, 30 amp and the other is 240v, 20 amp. Each one feeds an A/C unit and each are the service disconnects for those units.

I am planning on installing either a main breaker load center or main lug load center on the inside wall of the garage almost immediately behind the existing, main lug load center feeding the A/C units.

I have the option (I believe) to:

1. Leave the 2/0 100 amp conductor connected to the external main lug load center then run #6 cable via a new breaker, to a new, inside main lug load center; or
2. Reconnect the 2/0 conductor to a new, inside main breaker load center, then run the #6 via a new breaker out to the A/C service disconnect panel.

My intuition tells me choice #2 is better cause it allows me to flip the main breaker from inside the garage shop and turn all power off to my shop and to the A/C units while still allowing me the alternative to use the outside breakers in their original capacity as service disconnects while leaving the shop circuits powered up.

However, in this instance, I have a breaker (100 amp @ the house main) connecting to another breaker (the main breaker in the new garage load center). I am not sure if this is kosher or not...

Opinions would be appreciated.

Jim

 

[pattenp]

#2 is fine. The 100A breaker in the main is the over current protection for the 2/0 feeding the sub and the main breaker in the sub becomes a disconnect.

 

[Charles (in GA)]

Routing the power to the new panel first, then branching it out to the A/C and the new receptacles makes more sense (#2). This leaves you basically unrestricted in what power you draw in the garage, being only limited by the original 100 amp breaker in your house panel. Just make sure you have an appropriate sized breaker supplying the new #6 you are feeding the A/C with.

Charles

 

[Orionrising]

the real question is the #2 cable long enough to switch panels with it.

the second question is it 3 wire or 4 wire.
if 3 wire the inspector may not let you put it to a new panel.