shed subpanel

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  #1  
Old 07-15-07, 07:51 PM
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shed subpanel

I plan to use #6 wire and a 50a breaker to run 240 and 120 power to my 12X12 shed. What size wire should i use for the ground and should i pull the ground back to the main panel or using a grounding rod that would be just for the shed?

TIA
 
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  #2  
Old 07-15-07, 08:01 PM
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What are you going to have for loads at the shed? That is a pretty big wire and could supply up 65 amps if ran in conduit as thwn rated.

How far to the shed?

Are you using conduit?

#10 awg copper will be good for the ground wire up to a 60 amp breaker protecting the feeder. Equipment ground is sized by the overcurrent device used for protection of the feeder. Table 250.122 NEC

Sorry i just saw your second question. You need a ground rod at the shed but you are confusing it with the equipment ground wire ran with the sub-panel feeder. They have nothing to do with each other and serve different purposes. You need them both.
You need to run a 4 wire feeder to have the safest installation IMO. neutral and ground are seperate at the subpanel with a 4 wire feeder.

roger
 
  #3  
Old 07-15-07, 08:19 PM
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I agree that a 4-wire feed to the shed is best, but you MIGHT be able to choose to go with a 3-wire, if it will save significant money (basically just the cost of the #10). Will there be ANY other metallic paths to the shed, like metal pipes or phone wires?

And ditto on the ground rod. It's required no matter which feed you go with.
 
  #4  
Old 07-16-07, 03:08 AM
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i think the run is about 90 ft. most of it is in my attic and then going outside will be in conduit. so i will need to pull a ground from the main panel to the sub panel and hook it to the ground bus? where would the grounding rod ground go?

there will be no metallic paths or phone wires.

as for loads, i have a air compressor that is rated for 15A, im going to have 6 15A receptacles and 2 lights.
 

Last edited by best49erfan; 07-16-07 at 03:12 AM. Reason: added loads to answer question
  #5  
Old 07-16-07, 08:33 AM
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> so i will need to pull a ground from the main panel to the sub panel and
> hook it to the ground bus?

Yep. #10 bare copper or green.

> where would the grounding rod ground go?

Use a 5/8" x 8' ground rod driven flush to the earth near the point where the conduit enters the shed; you can drive the rod in the bottom of the wiring trench and bury it if you want to. Use an acorn clamp on the top of the rod with #6 copper wire. Run that into the shed and attach to the subpanel ground bus.

Make sure to remove the bonding screw or strap in the subpanel as per manufacturer's instructions. This usually requires you to buy an add-on ground bar kit.
 
  #6  
Old 07-20-07, 01:31 PM
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Originally Posted by ibpooks View Post
> so i will need to pull a ground from the main panel to the sub panel and
> hook it to the ground bus?

Yep. #10 bare copper or green.

> where would the grounding rod ground go?

Use a 5/8" x 8' ground rod driven flush to the earth near the point where the conduit enters the shed; you can drive the rod in the bottom of the wiring trench and bury it if you want to. Use an acorn clamp on the top of the rod with #6 copper wire. Run that into the shed and attach to the subpanel ground bus.

Make sure to remove the bonding screw or strap in the subpanel as per manufacturer's instructions. This usually requires you to buy an add-on ground bar kit.
So, both grounds will go to the grounding bar? and i have to have the neutral/gnd bus split.

What size conduit would i need for #6 wire? I dont have my uglys book at home. and what would you recommend for getting the wire down the wall and out side? I am on a slab. my plan was to install a double gang box and drill a hole in the back of it where the conduit would tie in, then install and LB and go into the ground.
 
  #7  
Old 07-20-07, 01:42 PM
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> So, both grounds will go to the grounding bar? and i have to have the
> neutral/gnd bus split.

Yes on both accounts.

> What size conduit would i need for #6 wire?

The code minimum for (3) #6 THWN and (1) #10 is 3/4"; however that is a pretty tight fit. I would recommend at least 1"; go to 1-1/4" if you ever want the capability of upgrading to 100A.

> my plan was to install a double gang box and drill a hole in the back of
> it where the conduit would tie in, then install and LB and go into the
> ground.

Your plan is okay. Most steel boxes have knockouts in the back to avoid the need to drill one. Use LB fittings to go into the buildings and 90 sweep fittings at the bottom of the trench.
 
  #8  
Old 07-20-07, 03:57 PM
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Originally Posted by ibpooks View Post
> So, both grounds will go to the grounding bar? and i have to have the
> neutral/gnd bus split.

Yes on both accounts.

> What size conduit would i need for #6 wire?

The code minimum for (3) #6 THWN and (1) #10 is 3/4"; however that is a pretty tight fit. I would recommend at least 1"; go to 1-1/4" if you ever want the capability of upgrading to 100A.

> my plan was to install a double gang box and drill a hole in the back of
> it where the conduit would tie in, then install and LB and go into the
> ground.

Your plan is okay. Most steel boxes have knockouts in the back to avoid the need to drill one. Use LB fittings to go into the buildings and 90 sweep fittings at the bottom of the trench.
Ben,

I was planning to use sweeps. Thanks for the advice.
 
  #9  
Old 08-19-07, 03:16 PM
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for the #6 going to the grounding rod i have 2 questions:

1. Can I use stranded cable or does it have to be solid?
2. does it have to be bare wire or can it have insulation?
 
  #10  
Old 09-03-07, 07:48 PM
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i found out about the grounding. i have run all the wire in the shed itself, but have not run the wire from the main panel to the subpanel, but hopefully will do that tomorrow. I did a test by hooking an old extension cord the ground, neutral, and one of the line leads. as soon as i did, it tripped the breaker for the extension cord. i took out the bonding screw and it did not trip after that. does this mean the inside panel has the bonding screw? should i leave it that way?
 
  #11  
Old 09-15-07, 05:04 AM
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Originally Posted by best49erfan View Post
i found out about the grounding. i have run all the wire in the shed itself, but have not run the wire from the main panel to the subpanel, but hopefully will do that tomorrow. I did a test by hooking an old extension cord the ground, neutral, and one of the line leads. as soon as i did, it tripped the breaker for the extension cord. i took out the bonding screw and it did not trip after that. does this mean the inside panel has the bonding screw? should i leave it that way?
Well, I just want to say that I appreciate all the information. I have managed to pull the wire all the way to above the main panel in the house. I have to drill a hole in the top plate and finish it up. I still have the question about the trip when i used an outlet for temp power. Could it have been that it was a GFCI breaker? The only load that got turned on was the light. I did take the cover off the main panel and the grounds and neutrals are tied together. So if I put the bonding screw in the subpanel, would that be the issue that makes it trip?
 
  #12  
Old 09-15-07, 07:18 AM
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If you have a GFCI breaker and the ground and neutral are bonded together downstream, that will cause the breaker to trip. A standard breaker doesn't care if neutral and ground are bonded.
 
  #13  
Old 09-15-07, 08:39 AM
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Originally Posted by ibpooks View Post
If you have a GFCI breaker and the ground and neutral are bonded together downstream, that will cause the breaker to trip. A standard breaker doesn't care if neutral and ground are bonded.
ahhh i see. So should I leave the bonding screw out of the subpanel?
 
  #14  
Old 09-17-07, 09:36 AM
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Yes, remove the bonding screw from the subpanel. For subpanels with four-wire feeders, the neutral and ground should be isolated.
 
  #15  
Old 09-18-07, 06:09 PM
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Originally Posted by ibpooks View Post
Yes, remove the bonding screw from the subpanel. For subpanels with four-wire feeders, the neutral and ground should be isolated.
By four-wire feed, you mean the two lines, a neutral, and the ground???

I finished pulling the wire in to the main panel, mounted the breaker, and hooked all the wires up. No problems to report. At least now at night if I have to go in my shed, i dont have to hunt for a flashlight!!!!
 
  #16  
Old 09-19-07, 07:28 AM
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Originally Posted by best49erfan View Post
By four-wire feed, you mean the two lines, a neutral, and the ground???
Yep.

At least now at night if I have to go in my shed, i dont have to hunt for a flashlight!!!!
Glad it worked out.
 
  #17  
Old 09-25-07, 03:37 PM
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Originally Posted by ibpooks View Post
Yep.



Glad it worked out.
Yup, finally done with it. I started putting up some pegboard and hanging tools on it. of course i put up nail guards where the holes in the studs are! look good. I will post a pic soon.
 
  #18  
Old 09-25-07, 04:30 PM
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49ers, eh?




Go Pats!
 
  #19  
Old 09-27-07, 01:28 PM
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Originally Posted by HotinOKC View Post
49ers, eh?




Go Pats!

You bet. Been a fan since I first learned about football. seen the good, seen the bad...just like all teams. No more spying, ok?
 
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