DIY Home Improvement Forum banner
1 - 20 of 28 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
I have a 50, 30 and 20 amp circuit that need to be brought over to a pre-existing shop approx. 100' out. I was gonna run separate lines of 4 AWG for the 50a. #8 for the 30a. and #10 for the 20a. Each circuit dedicated to specific load requirements, having it's own sub-panel. The 50a is for a lighting array, the 30a for a/c and the 20a for regular use shop lights and such.

Thanks
Layman
 

·
Registered
Joined
·
3,118 Posts
It would much simpler to run 4 wires and add a subpanel for those things, and build in a little extra for future expansion.
 

·
Licensed Electrical Cont.
Joined
·
7,829 Posts
It would much simpler to run 4 wires and add a subpanel for those things, and build in a little extra for future expansion.
It is also code required.

You can only run one multi-wire circuit or one feeder at most to a detached structure.
 

·
Registered
Joined
·
5,067 Posts
It is also code required.

You can only run one multi-wire circuit or one feeder at most to a detached structure.
Thats right. See this NEC article.

225.30 Number of Supplies. Where more than one building
or other structure is on the same property and under
single management, each additional building or other structure
that is served by a branch circuit or feeder on the load
side of the service disconnecting means shall be supplied
by only one feeder or branch circuit unless permitted in
225.30(A) through (E). For the purpose of this section, a
multiwire branch circuit shall be considered a single circuit.

There are some exceptions, but they do not apply to your project.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #6 ·
Thanks for the responses guys. OK, so how do I pull those 100 amps off those three main breakers ?

Layman

A lil help guys?
 

·
Registered
Joined
·
671 Posts
You dont. You take those three breakers out and put in a 100 amp breaker and run the appropriate AWG size to the structure and put in sub-panel.

You cannot utilize all three breakers to get 100 AMP service.

Now, if you are really needing a 50, 30 and 20, you may want to consider running 125 or 200 amp service to this structure.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #9 ·
Andrew, so if I'm interpreting this correctly; I need to replace the 3 breakers with 1 100amp ? Now, the breakers are in different parts of the panel so I need to move the pre-existing breakers (that are in use) to make room in an area to fit the 100 amp ? Then run my 100amp sub-panel ...............

hayewe yes that too lol

What gauge wire would you recommend for 100' feet out on 100amps ?
Thnks guys
 

·
Licensed Electrical Cont.
Joined
·
7,829 Posts
Let's start from scratch.

Forget adding up the circuits. It doesn't work that way.

What are the loads that will be in the panel. And by this I mean the actual draw?

I agree that you probably need a 100A sub-panel, but I am also pretty concerned that you are in over your head with this project.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #11 ·
SP thank you for your help and concern I have a 50amp sub panel that will go off the 100 sub I plan on adding a 30a a/c unit to cool our shop space and need a 20a circuit to supply the shop with shop lights and other low amp needs

Not to sure about actual draw I'm over building for future needs
 

·
Registered
Joined
·
2,294 Posts
I'd install a 125 amp breaker in the main panel, run 3 copper #2's and a #8, underground in 1 1/2 PVC, to a sub panel in the workshop. Don't forget the ground rod(s).
 

·
Registered
Joined
·
671 Posts
I'd install a 125 amp breaker in the main panel, run 3 copper #2's and a #8, underground in 1 1/2 PVC, to a sub panel in the workshop. Don't forget the ground rod(s).
This is my recommendation and similar to what I am doing as well. (except for running 100 amp service on #2s instead of 125 amp service and running 4 #2 copper.)
 

·
Licensed Electrical Cont.
Joined
·
7,829 Posts
(except for running 100 amp service on #2s instead of 125 amp service and running 4 #2 copper.)
WHY #2? And WHY four???
 

·
Registered
Joined
·
1,124 Posts
clarifying Layman's Electrical needs!

Just enhancing Speedy Petey's advice! Forget about the 50 Amp. Subpanel and other loads. You will be pulling everything off the 100Amp. Subpanel in the detached structure! And in the Main Panel, there should be space for the 125Amp. 2-pole breaker that will protect the sub-feed to the panel in your shop!:yes::no::confused1:???!!! Don't Drink and Drive!!!
 

·
Registered
Joined
·
671 Posts
WHY #2? And WHY four???
At my last house, I built a 30x56 barn and ran 100 amp service to it.

I ran 4 lines, and grounding rods and the inspector passed.

2 hots ,1 neutral, 1 ground.

Are you saying, I only need 2 hots, 1 neutral and bond the neutral and GEC in the sub-panel?

I wonder why the county passed the install at the old place then.

I am using #2 because that is what I have on hand and it is around 200-250' to the 40'x68' shop.
 

·
Licensed Electrical Cont.
Joined
·
7,829 Posts
No, by "why four #2's" I meant why #2 for the ground. I see now that you have it on hand which is as good a reason as any. :thumbsup:
 

·
Registered
Joined
·
671 Posts
No, by "why four #2's" I meant why #2 for the ground. I see now that you have it on hand which is as good a reason as any. :thumbsup:
If I was running short on #2 and had to go buy some wire just for the found, what is the minimum size I can run in CU? #4?


and now back to you regularly scheduled programming.
 
1 - 20 of 28 Posts
Top