Shed wiring

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Old 08-21-06, 05:34 AM
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Shed wiring

I've got pvc conduit running into my shed; will bring in 12g THWN to a switch (for main disconnect for shed). From there, I will run a couple of lights and a convienence outlet.
Do I have to use UF, conduit, or can I use NM from the switch onwards?
Thanks!
bob
 
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Old 08-21-06, 05:37 AM
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This is a judgement call. I would say that wiring in the the shed is exposed and subject to damage, at least any wire along the walls. This means that conduit (or some other form of protection) would be required.

Don't forget receptacles must be GFCI protected.
 
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Old 08-21-06, 09:24 AM
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As long as the shed is enclosed from the weather, NM-B cable is just fine inside the shed. If you think that the cable could be damaged by tools or other activities inside the shed, consider using THHN in EMT conduit. Conduit would almost never be required in a residential storage shed, but is always allowed if you prefer to have greater protection of the wires.
 
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Old 08-21-06, 09:43 AM
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This is about the type of construction of the shed. If it is 2x4 wood members and you can staple the nm cable on the side of them then use it. If the wires have to be on the face of the wall then they need protection.

I do not agree with the "Conduit would almost never be required in a residential storage shed" comment.

IMHO the nature of a shed suggests tools and such being thrown in there or leaned against walls etc. Most of the time the wires ARE subject to physical harm. The final decision rests in an inspector. If one will not be called.. I suggest err on the side of safety.
 
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Old 08-21-06, 09:52 AM
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Ben,

What do you base your answer on? Most sheds that I know of are worse than garages when it comes to clutter and items stuffed inside.

Most inspectors frown on NM exposed along garage walls, because of the risk of damage. I would think they would feel the same about sheds.
 
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Old 08-21-06, 10:29 AM
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I don't mind the conduit (PVC for me if ok with THWN?); I just don't like getting the stranded wire under the wire terminals on switchs and receptacles. It always seems not as secure as solid with a few stray strands that squish out under the screw.
 
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Old 08-21-06, 10:35 AM
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Originally Posted by bob22
I just don't like getting the stranded wire under the wire terminals on switchs and receptacles. It always seems not as secure as solid with a few stray strands that squish out under the screw.
This takes practice. There are tips that people will probably supply here, to make this easier.

You can buy solid wire, it doesn't have to be stranded.

Incidentally, your disconnect entering the shed could be a GFCI switch, sometimes called a faceless GFCI.
 
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Old 08-21-06, 11:12 AM
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The easiest way to deal with stranded wire on receptacles and switches is to use back-wired (NOT back-stabbed) devices. Back-wired uses a pressure plate under the screw to contain the strands and distribute the screw pressure.

The back-wired devices cost a bit more but they are usually of much higher quality.
 
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Old 08-21-06, 11:13 AM
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Racraft,
The feed to the shed is already GFCI protected so it would be redundant but I appreciate the suggestion. I know the last GFCI outlet I installed had a back-stab-like hole that accepted stranded wire and tightened up as the screw terminal was tightened. I don't know of regular outlets or switches with this feature, anyone?
 
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Old 08-21-06, 11:32 AM
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Originally Posted by racraft
What do you base your answer on? Most sheds that I know of are worse than garages when it comes to clutter and items stuffed inside.
My experience is that the inspectors rarely require additional protection for NM-B cable installed in residential garages or sheds so long as the cable is run in the stud cavities, not on the faces.

I agree that the cable probably will be exposed to some damage in a garage or shed, but I haven't seen the protection requirement enforced. I have EMT in my own garage, but it's a lot of additional work and expense that isn't required in many situations.
 
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Old 08-21-06, 11:36 AM
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Originally Posted by bob22
Racraft,
The feed to the shed is already GFCI protected so it would be redundant but I appreciate the suggestion. I know the last GFCI outlet I installed had a back-stab-like hole that accepted stranded wire and tightened up as the screw terminal was tightened. I don't know of regular outlets or switches with this feature, anyone?

Pressure plate connection type devices are available at most big box stores and supply houses. You will not find them in the bargen bin.
 
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Old 08-21-06, 03:21 PM
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I guess I'll go with conduit and look for the backside pressure-plate type switches and receptacles. Thanks to all.
Bob
 
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