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Old 03-08-2008, 02:14 PM   #1
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Subpanel - detached structure


I'm installing a subpanel in a detached building. Thanks to stubbie for his great explanation of the six hand rule in his post here: http://diychatroom.com/showthread.php?t=16776

I still have a couple of questions though. I have to make an egress from my home (crawl space with brick veneer) and an ingress into the shed (post and pier, wood siding). If I read the codes correctly, I can use sch 40 pvc for the underground run but everything above ground must be sch 80. Can someone confirm that's correct?

For the egress from house should I just use a masonry bit to get through the foundation (above ground) then elbow it in to below ground? If not, how should this be done? If so, can someone help me out with the clamping requirements? I presume I'll need to have it secured in some fashion. I can come up with something, but I'd like it to pass inspection.

For the ingress to the shed, should I just run a piece of sch 80 pvc up through the sill plate through to the sub panel?

Thanks in advance for your help.

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Old 03-09-2008, 12:56 AM   #2
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Subpanel - detached structure


Use an LB-type conduit body to come from the house to the trench. At the building, bring the pip out of the slab, through the sill plate, and directly into the subpanel, as you said. 4-wires, a ground rod and disconnect or main rated for 60 A is also required.

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Old 03-09-2008, 09:39 AM   #3
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Subpanel - detached structure


Inphase, thanks for your reply. I was aware that I would need a ground rod. I didn't think I would need a disconnect at the structure if I used a main lug only panel and didn't violate the six hand rule.

Also, the shed is on a post and pier foundation, not a slab. I was thinking I would just bring the trench up to the location of the sill plate nearest the entrance of the shed (where the panel will be). From there, is it okay to just bring the conduit up out of the ground through the sill plate or is more protection required for the conduit?
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Old 03-09-2008, 11:42 AM   #4
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Subpanel - detached structure


If you are digging a trench, why not go all the way to where the panel is located. You are only allowed 360 degrees in total bends before you must install a box or enclosure. Just take the trench all the way directly under the panel. It depends on your location (local requirements) regarding the PVC. If not subject to physical damage you can bring it up directly into the panel. We stub up PVC for POCO services in my area. It's not protected. Make sure you strap it once it enters the floor.

I assume Stubbie explained all the specifics about wiring this up? If not, post again.
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Old 03-09-2008, 12:42 PM   #5
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Subpanel - detached structure


I am assuming that I posted a diagram of how this should be wired but when I go to that link I am not finding a post where I did that or explained the 6 hand rule.
In my opinion a disconnect is required or a main breaker is required. The controversy occurs when applying the 6 hand rule to a main lug panel for a detached structure. There are many inspectors that will allow 6 sweeps of the hand or less to satisfy the disconnect requirement in article section 225.36. It is my opinion that they are incorrect and would like for you to consider using a main breaker or a remote disconnect at the shed. The world doesn't come to an end either way but it is advantageous to have a one movement disconnect both for safety and convenience.
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Old 03-09-2008, 02:48 PM   #6
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Subpanel - detached structure


Quote:
Originally Posted by Stubbie View Post
I am assuming that I posted a diagram of how this should be wired but when I go to that link I am not finding a post where I did that or explained the 6 hand rule.
In my opinion a disconnect is required or a main breaker is required. The controversy occurs when applying the 6 hand rule to a main lug panel for a detached structure. There are many inspectors that will allow 6 sweeps of the hand or less to satisfy the disconnect requirement in article section 225.36. It is my opinion that they are incorrect and would like for you to consider using a main breaker or a remote disconnect at the shed. The world doesn't come to an end either way but it is advantageous to have a one movement disconnect both for safety and convenience.
So, you would only use an MLO panel for a sub panel in the same structure as the main panel?
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Old 03-13-2008, 08:15 PM   #7
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Subpanel - detached structure


I looked at Lowes and found what GE is labeling a workshop panel, essentially a small panel with a 100 amp main. It is well within my price range for the project, but I don't need 100 amps on the circuit (and I'd rather not spend the money to run higher cost cable). Can I still put a 60 amp breaker in the main panel to feed this new panel with the 100 amp main or is there some problem with my disconnect being rated higher than the feeder from the main panel?

BTW, thanks for all the help on this.
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Old 03-13-2008, 09:11 PM   #8
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Subpanel - detached structure


You can indeed feed a 100 amp main breaker panel with a 60. The wire needs to be good for 60 amps, as it's protected by the 60 at the feed end.

This is actually a pretty common installation.

Rob.
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Old 03-13-2008, 09:29 PM   #9
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Subpanel - detached structure


Quote:
So, you would only use an MLO panel for a sub panel in the same structure as the main panel?
Yes, that would be correct.
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Old 03-13-2008, 09:49 PM   #10
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Subpanel - detached structure


Quote:
Originally Posted by former33t View Post
I looked at Lowes and found what GE is labeling a workshop panel, essentially a small panel with a 100 amp main. It is well within my price range for the project, but I don't need 100 amps on the circuit (and I'd rather not spend the money to run higher cost cable). Can I still put a 60 amp breaker in the main panel to feed this new panel with the 100 amp main or is there some problem with my disconnect being rated higher than the feeder from the main panel?

BTW, thanks for all the help on this.
The 100 amp main in the sub panel will simply function as a disconnect for the panel. The feeder wires will be protected by the 60 amp breaker in your main panel. As micromind stated, this is a very common and acceptable installation.

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