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msajeep 08-18-2007 01:22 PM

Running electric to a shed
 
I am looking to run an electric line to my shed I just built. I already have a subpanel at my hottub with two open spots for a breaker on it, so I plan to tap into that. It's about a 75 foot run to the shed. I plan to dig a trench and put the line in PVC. I don't want to use the underground cable because it's more expensive and you have to dig deeper. My question is whether you can use regular old 12/2 romex inside of the pvc that will be underground? I know most of the time you use stranded cable inside the pvc, but I already have some romex leftover and the stranded seems to be more expensive. Any help it appreciated. Thanks

troubleseeker 08-18-2007 10:53 PM

It is best IMO not to use the UF cable, whatever your reason. I cannot understand how it is even allowed to bury ac voltage wire unprotected. Step up to 1" conduit, and I would invest in a coil of #10 instead of the #12 you already have. The larger wire will offer an ample supply line for any future modest power demand you may want from in the garage (power tools, landscape lighting, small above ground pool pump. It is easier and cheaper to have a larger wire than you need, than to have to resupply later. As you assemble the conduit, give a squirt of wire pulling lubricant into the end of one pipe at each joint, being sure to keep it off of the gluing area. I do not know of any code that prohibits "Romex" in this application, but I'm sure some electricians will reply if so.

HouseHelper 08-19-2007 08:41 PM

Wiring underground is considered a wet location, so you must use THWN single conductor wires or UF cable. If all you want is one circuit, three runs of #12 THWN (hot, neutral, ground) in 1/2" PVC will suffice. You will need a disconnect at the shed, but this can be a simple snap switch. I would use a GFCI breaker at the subpanel, but you could also use GFCI receptacles at the shed.

troubleseeker 08-19-2007 09:23 PM

Quote:

Originally Posted by HouseHelper (Post 58481)
Wiring underground is considered a wet location, so you must use THWN single conductor wires or UF cable. If all you want is one circuit, three runs of #12 THWN (hot, neutral, ground) in 1/2" PVC will suffice. You will need a disconnect at the shed, but this can be a simple snap switch. I would use a GFCI breaker at the subpanel, but you could also use GFCI receptacles at the shed.

Glad to see your clarification on that.:thumbup: I did not know that single conductor wires were required in this situation. Curious.. do you know why ?, it seems that the extra jacket on the "romex" would be beneficial.

How about Uf cable in the conduit? also a no no?

SecretSquirrel 08-19-2007 09:44 PM

No one has mentioned the minimum burial depth for conduit. I'm going on memory but I *think* it's 18". Someone chime in if it's different.

Stubbie 08-19-2007 10:03 PM

If the circuit is gfci protected before it goes outside and is 20 amps or less it can be buried at 12". Otherwise you are correct for most residential applications using pvc.

Stubbie

Stubbie 08-19-2007 10:21 PM

Quote:

Glad to see your clarification on that. I did not know that single conductor wires were required in this situation. Curious.. do you know why ?, it seems that the extra jacket on the "romex" would be beneficial.

How about Uf cable in the conduit? also a no no?
Romex (NM-b) is not allowed underground or anywhere in a classified wet location. It can be ran in conduit but not underground or outside in a wet environment. The jacket is no help if the conduit floods.... it is not rated to be wet. The wires inside are rated thhn not th"w"n... w=wet. In a nutshell you must be in a dry location indoors to use romex.

UF can be ran in conduit underground ,however why do it? It is more expensive than individual conductors. So direct bury it that is what they make it for.

Stubbie

troubleseeker 08-19-2007 10:53 PM

Quote:

Originally Posted by Stubbie (Post 58514)
Romex (NM-b) is not allowed underground or anywhere in a classified wet location. It can be ran in conduit but not underground or outside in a wet environment. The jacket is no help if the conduit floods.... it is not rated to be wet. The wires inside are rated thhn not th"w"n... w=wet. In a nutshell you must be in a dry location indoors to use romex.

UF can be ran in conduit underground ,however why do it? It is more expensive than individual conductors. So direct bury it that is what they make it for.

Stubbie

Was just curious about the UF in conduit, agreed it makes no sense to pay the extra cost for it to put it in pipe. Can't change my mind though about never allowing direct burial on any of our jobs. Conduit is plenty cheap enough as far as I'm concerned.

msajeep 08-19-2007 11:40 PM

Thanks for the info, although I'm still a little confused as to whether I can tie into my subpanel for the hot tub. Basically I have 6 gauge wire running form a subpanel in the house that goes to a 3 breaker subpanel outside my house. In this subpanel(which is mounted on the side of my house by the hot tub) I have a GFI breaker which is wired and that goes to the hot tub but there are also 2 other empty spots for additional breakers. Why woudl they put two more open spots in the subpanel if you couldn't use them?? Any help is appreicated

Stubbie 08-20-2007 11:40 PM

I can't find anything that says you can't do as planned. It's a funny coincidence but I am doing a very similar installation early next week. I've spent a few days making dang sure I can use the spa panel. Looks like you have no problems using the spa panel nor do I.

Stubbie

wooderson 08-22-2007 09:49 PM

Quote:

Originally Posted by msajeep (Post 58536)
Thanks for the info, although I'm still a little confused as to whether I can tie into my subpanel for the hot tub. Basically I have 6 gauge wire running form a subpanel in the house that goes to a 3 breaker subpanel outside my house. In this subpanel(which is mounted on the side of my house by the hot tub) I have a GFI breaker which is wired and that goes to the hot tub but there are also 2 other empty spots for additional breakers. Why woudl they put two more open spots in the subpanel if you couldn't use them?? Any help is appreicated


Is your #6 al is assume? Also what size ocpd do you have the wire on?

WireNutter512 04-12-2011 03:24 PM

Quote:

Originally Posted by SecretSquirrel (Post 58494)
No one has mentioned the minimum burial depth for conduit. I'm going on memory but I *think* it's 18". Someone chime in if it's different.


18'' is correct for running pvc underground :thumbsup:

duckdown 04-12-2011 04:33 PM

Code will allow you to go as shallow as 6" (instead of 18") but then you need to cover with concrete....

vsheetz 04-12-2011 11:34 PM

Summary:
  • single 120v 20a circuit
  • GFCI at the spa subpanel end
  • three runs of #12 THWN (hot, neutral, ground)
  • in 1" conduit, buried 12"
  • some kind of a disconnect at the out-building
Disagreements?

Saturday Cowboy 04-13-2011 12:53 AM

I can't see why you wouldn't go 120/240v, what do you plan on using?


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