Shed Wiring

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Old 05-12-20, 08:20 PM
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Shed Wiring

I had electric service brought to a shed. Currently there is an electric panel with several breakers in the shed. I plan on running the wiring and circuits within the shed myself.

If the inside of the shed will remain unfinished - simple 2 x 4 studs - what type of cable can/should I use? Recommended by code?
1. Is NM cable allowed? - It will be exposed - If allowed am I required to drill holes through the studs to run the cable rather then across the studs? Must it be enclosed in conduit for vertical runs? Can I run NM in conduit throughout?
2. Should I use metallic cable? If so - through studs or across?
3. Can I use THHN wires in conduit to the various outlets switches, etc?
4. Can I use UF cable and run it like I would run NM cable?
 
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Old 05-13-20, 04:31 AM
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There is no location in your profile, even with one posted I'd still ask my local building dept. these questions because the codes can vary from county to county.
It's not that much more work to drill the studs and not have the wiring running across the face of the studs.
That way in the future if anyone wanted to finish the shed, or do something as simple as running peg board over the walls it's not in the way.
For sure I would not be using UF, it's far to stiff and will be a PIA to wrap around the screws.
All wiring should be 12 gauge, and all outlets will need to be GFI protected.
 
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Old 05-13-20, 05:53 AM
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If I'm not mistaken you aren't allowed to have exposed wires/cables under 7' Your wires should be in conduit unless covered by drywall/plywood. That said, the wiring in my barn/shop is exposed although any cable that is run horizontally between studs has a short 2x4 above it which prevents anything being hung on the wire.
 
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Old 05-13-20, 06:35 AM
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Being that this is a shed just follow NEC 334 for NM wire and also refer to NEC section 300 for wiring methods. You can run the NM along the side of the studs keeping them back at least 1.25 inches from the nailing surface and also through bored holes that are also at least 1.25 inches from the nailing surface. If not having wall covering use running boards along cable where the cable runs perpendicular to studs through the stud cavity. Protection by using conduit is only required where needed when the cable may be subject to damage. This is all provided there are no local requirements that differ from the NEC.
 
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Old 05-13-20, 07:28 AM
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Thanks for the replies. I'm located in NY.

The reason for my question is I've heard much conflicting information. Originally just figured I would use NM.
I've come across information saying that a detached outdoor structure like my shed is almost like an exposed location (even though it is a "dry" enclosed structure) and NM shouldn't be used. Regarding placing the NM in conduit - also conflicting information - don't do it - too much heat generated or you can do it but need to use larger conduit. Or I've heard you should only run THHN in the conduit.

Regarding drilling holes through the studs if I run NM cable - are you saying that the cable needs to be supported on running boards from stud to stud rather then just in the "air"?

Can I use THHN in conduit throughout the interior?
 
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Old 05-13-20, 11:13 AM
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I will only speak as to what is allowed by the NEC. First, NM is allowed to be used in your shed being that the shed is an enclosed dry area. Second, NM can be placed in conduit but the conduit has to be sized properly by the large dimension of the NM. It is not advisable to use NM in a complete conduit system. Conduit is usually used as sleeves for protection of NM cable. Third, running boards between studs is not for supporting the cable but for protection since the cable is not being protected by any wall covering nor is it running along the surface of a framing member. And yes you can use conduit with THHN/THWN for the circuits inside if that's what you want.
 
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Old 05-13-20, 12:04 PM
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I would consider MC cable. NM exposed at lower levels I just donít like. Rodent chews, tools, and other stuff banging around are threats. I might use EMT depending on the distances and stud interferences. Not at all convenient on a fully studded wall tho.
 
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Old 05-14-20, 02:37 PM
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Is the concern for running NM in EMT conduit overheating? Is that more of a perceived risk than a real one? Why is it not advisable to use it in a complete circuit? From a layman's standpoint it seems like it would still be superior than running NM uncovered.

When you consider the studs are only 2 x 4s and the outside wall only adds maybe an inch or less of thickness it doesn't leave you a lot of room to allow for drilling a hole 1.25" back from the interior nailing surface of the studs and 1.25 " back from the other side of stud/outside wall.

If cost was not an issue how would you rank the different methods? What would most licensed electricians most likely recommend?
1. THHN/THWN in EMT
2. MC Cable (Would you still run it through the studs?)
3. NM Cable
4. Something else?
 
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Old 05-14-20, 07:00 PM
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Stuffing NM in EMT that has bends is not as easy as pulling thhn. So, zero benefit.
MC would go thru the same holes as u would make for NM.
How long a runs are these?
 
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Old 05-14-20, 07:29 PM
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Not long - the shed is only 8 x 10 so from the panel to the furthest point maybe 25 ft
 
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Old 05-14-20, 07:34 PM
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Long ago, I did some emt stuffing in a studded wall. I tend to doubt a pro would do this unless the local code mandated it. Lots of chopped short sections and misaligned stud holes tend to make this a flail. AC flex is so easy...
 
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Old 05-15-20, 04:53 PM
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Rather than AC, I'd use MC cable.
 
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