220 outlet in sub panel detached garage wiring help

Reply

  #1  
Old 08-10-20, 04:43 PM
J
Member
Thread Starter
Join Date: Feb 2009
Location: usa
Posts: 58
Received 0 Votes on 0 Posts
220 outlet in sub panel detached garage wiring help

So I have a sub panel in my detached Garage that was wired from the house with THWN 8ga red 8gablack 8ga white and 10ga Ground Green. The sub panel passed inspection and it is supplied from a 40a dbl pole breaker in the houses service panel. The ground bar is bonded to the sub panel and also to 2 8ft rods outside of the garage per towns request with 6ga wire and copper clamps. The neutral is isolated from the sub panel and returns to the service panel in the house. I want to put a 220v 6-50r outlet in, and am aware that is a 50amp outlet. I plan to attach it to a 30amp dbl pole breaker in the sub panel, which I believe is ok because it will be the only outlet on that circuit. I plan to use 8ga for supply to the 6-50 outlet for a small plasma cutter. I donít anticipate the need for over the 30 amps on that circuit. My biggest question is when hooking the outlet up for the 220 do I use red / black and green bringing the green to the bonded ground bar in the sub panel or do I use red/ black and white and connect it to the neutral bar that is isolated from the sub panel (not bonded). I am pretty sure no neutral is needed for 220 but was not sure how that changes on a sub panel with separate neutral and ground bars. I also wanted to know if a wire supplying the outlet should all be 8ga or do down rate any (ground 10ga)? Sorry for the long post .Thanks for any help.
 
Sponsored Links
  #2  
Old 08-10-20, 05:09 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,446
Received 1,021 Votes on 947 Posts
Do I use red / black and green bringing the green to the bonded ground bar in the sub panel
Yes..... two hot legs and ground..... no neutral.

That's a 50A receptacle but if you are only using it on a 30A breaker then you can wire it in #10.
 
  #3  
Old 08-10-20, 05:55 PM
J
Member
Thread Starter
Join Date: Feb 2009
Location: usa
Posts: 58
Received 0 Votes on 0 Posts
Thanks. I had an extra 40amp breaker and was going to use that or the 6-50 outlet, but figured that may not be ok with the house service panel only supplying the sub on a 40amp breaker and 8/8/8/10 wire. Thanks again. Have a great night.
 
  #4  
Old 08-10-20, 06:03 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,446
Received 1,021 Votes on 947 Posts
Will your device run on 30A ?
You can use a 40A breaker but then you need to use larger wiring.
 
  #5  
Old 08-10-20, 06:26 PM
J
Member
Thread Starter
Join Date: Feb 2009
Location: usa
Posts: 58
Received 0 Votes on 0 Posts
Yes it is a dual voltage 110/220 plasma cutter and most likely wont tax it over the 30amps on 220v. I just thought about the 10ga ground coming from the service panel and it had me second guessing the 40amp. The sub panel is on a 40amp breaker protecting the line in the service panel. If I used a 40amp dbl pole in the sub panel on the 220 6-50 outlet on 40 amp all hot, hot & ground 8ga connected to a sub panel thats connected to the service panel by 8ga hot, hot, neutral with 10ga ground. The 40amp breaker in the sub panel would be better but didnt want to push the limits, figuring a nuisance trip is the worst case on a 30amp breaker if I over do the demand. Is that over thinking it?
 
  #6  
Old 08-10-20, 06:29 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,446
Received 1,021 Votes on 947 Posts
The ground is only for safety. It has nothing to do with the operation of the circuit.
It only needs to be a certain percentage of the current carrying wires.

Even with your welder.
Nothing passes thru the ground wire unless there is an internal short in the welder.
 
  #7  
Old 08-10-20, 06:48 PM
J
Member
Thread Starter
Join Date: Feb 2009
Location: usa
Posts: 58
Received 0 Votes on 0 Posts
Sound great now I will figure the final set up and get it done.I might just do the 40amp with 8ga and have less of a risk of any nuisance tripping. Thanks again.
 
  #8  
Old 08-11-20, 07:06 AM
P
Member
Join Date: Feb 2016
Location: United States, Virginia
Posts: 1,435
Received 93 Votes on 73 Posts
Use the #8 on a 40A breaker with the 50A receptacle and you are good to go. The equipment ground for the circuit can be a minimum of #10.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: