# Wires to the Shed - Would you choose to bury wire or run conduit?



## Don2222 (Oct 27, 2011)

Hello

*What did you or would you do?*

I am planning on a 2 foot trench but are those PVC conduits with the expansion joints really needed? Direct burial electrical wire OR THHN / THWN ??

*Also should there be stones in the trench for drainage?*

THW = Thermoplastic PVC-insulated building wire, Heat resistant +75Â°C/+167Â°F, for Wet and dry locations, flame retardant
THHN = Thermoplastic PVC-insulated building wire, Nylon jacket, +90Â°C/194Â°F, 600 V, for dry and damp locations 

http://www.caledonian-cables.net/download/THHN-THWN PVC-Nylon Insulated PVC Sheathed Cables.pdf

Here is what some people did.
http://www.diychatroom.com/f18/opinion-would-you-choose-bury-wire-run-conduit-shed-45275/index2/

Click pic to enlarge


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## Backwoods Savage (Oct 27, 2011)

We recently wired our shed and simply dug a trench and laid the wire in. Nothing added to the trench except the wires and also only went about a foot deep.


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## yooperdave (Oct 27, 2011)

i have never done it any other way than just burying the cable in the trench. (outdoor rated, of course) i have even seen some places that have used "regular" romex (indoor rated) buried in a trench that are still working to this day!  one was run in the 60's or 70's and has never had troubles!  gotta find that hard to believe with the freeze/thaw cycle every year.
as far as putting rock in the trench for drainage...no-don't need it.


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## thinkxingu (Oct 28, 2011)

When I wired my shed, I ran conduit--didn't add much money, didn't add much work, but certainly added lots of flexibility.  One year later, wanted to add speakers off my garage system--just pulled the wires through the spare piping.

I go by the theory that a few dollars now will save me a lot later.

S


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## smokinj (Oct 28, 2011)

Backwoods Savage said:
			
		

> We recently wired our shed and simply dug a trench and laid the wire in. Nothing added to the trench except the wires and also only went about a foot deep.



+1 and under ground wire.


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## midwestcoast (Oct 28, 2011)

+1 You don't need stone for this application.  Wire's expensive when you start ding long runs, I'd shop around a bit for the best price. PVC conduit is cheap, if you think you're getting a benefit from the extra work & you have the time then go for it. You don't have to though, that's what direct burial wire is made for no?


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## JustWood (Oct 28, 2011)

thinkxingu said:
			
		

> When I wired my shed, I ran conduit--didn't add much money, didn't add much work, but certainly added lots of flexibility.  One year later, wanted to add speakers off my garage system--just pulled the wires through the spare piping.
> 
> I go by the theory that a few dollars now will save me a lot later.
> 
> S


Agreed,,, especially if vehicles or anything heavy may be run over it.


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## billb3 (Oct 28, 2011)

pvc conduit at two feet was code here. filled around the pipe with sand.
Wiring inspector failed the job, electrician had to come back, remove the sheathed wire and run individual wires / unsheathed.
Must be something new.
Also because my garage walls  are  unfinished there couldn't be exposed  (even sheathed) wire to the box, had to be solid PVC conduit all the way.
My town can be awful adopting anything new and the wiring inspector is the biggest [[censored]] in the state.


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## seige101 (Oct 28, 2011)

If you want to go direct burial you want UF cable. It's like a romex with a solid rubber/plastic insulation jacket.

Spend the extra few bucks and run PVC. 3/4" pvc is about $1.50 for a 10' stick and about 2.50 for a 10' stick.
Run a spare that way you could run phone, internet or speakers out there too.

Billb, you aren't allowed to run romex in conduit anymore, there is concerns about the wire over heating..


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## smokinj (Oct 28, 2011)

This is a shed right? lol without 3phase?


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## cottonwoodsteve (Oct 28, 2011)

Some ideas;
Do it to code or it may bite you when you try to sell the house or have an insurance claim.
If you use a conduit, add a small rope, synthetic so it doesn't rot. Then in the future you can pull through other wires, speaker or phone etc. If using plastic, pull rope back and forth a little so it doesn't stick in the joint glue.
Check your code but it may cause problems if you connect the ground wire to a ground in the shed if it is already grounded at the house.
If shed can be damp or wet Use a GFI breaker on the circuit or at least on the outlets.

Remember when plumbing, not doing it correctly you just have a leak.
Not doing electrical correctly can be deadly.
If you just want a little light, maybe think of low voltage, 12 volt, landscaping lighting. Then you can even light the path to the shed.


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## nate379 (Oct 28, 2011)

What is the power in the shed going to be used for?

I put up a shed last summer.  Ran a 10/3 UF wire from my garage (where the panel is) out to the shed.  Dug a trench 3ft and put it in there.  3ft is code in most areas.  I would be worried about only going a foot, would be very easy to pound in a stake right over it or hit with rototiller, etc.

I direct buried it because at the time I was told you can't run UF wire in conduit because it could overheat.  I have been since told that was bad info.  In any case when I buried it I made sure to use clean soil with little to no rocks so it wouldn't cut into the wiring.  In the same trench I did run a 1.5" conduit, but that was for the 3/4" air hose that goes into the garage.

In the shed I put a small breaker panel and wired the building just the same as it were a house or garage. Circuit for my 240v air compressor... then circuits for lights, outlets and also put an outlet outside as well as a flood light.

Had to put 2 grounding rods at the shed as well.  The ground goes from the garage panel to the shed, but also requires it's own ground rods.


If you are just putting power in the shed for a couple lights/outlets you can run the power into a junction box and split off that, don't need to do like I did.  You are limited to ONE circuit though.

I kind of wish I had used a larger wire to the shed.  With the 10/3 I'm good to 30 amps, 240v.  Had I thought things out I would have allowed for future addition of a ~10K gen set.... I should have trenched a nat gas line as well... for a heater in the shed and for the gen set.

BUT... whoulda shoulda coulda... there's always something that you miss you know?


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## jebatty (Oct 28, 2011)

PVC conduit can be helpful if you have gophers. I had 300 feet of 220V/200 amp cable trenched to my machine shed, gophers found the soft backfilled trench an ideal spot to tunnel, and in a year blew out the cable -- about a 10' section literally vaporized underground. The electrician gave me a good deal on laying a whole new cable, this time in conduit. Several years have gone by now and no more problem. Should have used conduit the first time.


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## semipro (Oct 28, 2011)

Suggestion.

After you lay whatever you bury in the trench and backfill a bit, whether cable or conduit; lay some red plastic "warning" tape along the length of the trench about 6" above your wire/conduit.   That way in the future anyone digging and likely to hit the wire will encounter the tape first and hopefully figure out what's going on. 

Its easy and cheap to do and may prevent hardship or even death later.

I cringe whenever I dig in my backyard between my well and house cause I know there's a wire in there somewhere.  If I'm lucky when I finally do hit it the line won't be energized.  Now that I think about it I could just turn off the breaker, duh.


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## jebatty (Oct 28, 2011)

> ... cause I know thereâ€™s a wire in there somewhere...



Use a couple of L-shaped divining wires, hold out parallel to the ground and walk back and forth about where you think the underground cable is, the wires will bend down to the ground when you cross the underground cable, mark the location.


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## firefighterjake (Oct 28, 2011)

jebatty said:
			
		

> > ... cause I know thereâ€™s a wire in there somewhere...
> 
> 
> 
> Use a couple of L-shaped divining wires, hold out parallel to the ground and walk back and forth about where you think the underground cable is, the wires will bend down to the ground when you cross the underground cable, mark the location.



I know there are folks who swear by this method to locate wires, water, etc. . . . but this is just one time where I am a bit skeptical of the thing working . . . unless someone can show me the science of it I would surmise that folks are proably either picking up on subliminal clues as to where the wiring or best source of water may be or they're just getting lucky.


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## semipro (Oct 28, 2011)

firefighterjake said:
			
		

> jebatty said:
> 
> 
> 
> ...



Never has this or "dousing" been proven to work in any setting with any kind of scientific rigor.  

Well constructed studies have been done to test dousing and no one has (yet) demonstrated any ability to detect anything with any accuracy better than shooting an arrow into the sky to see where it lands.  

I'm not saying its not possible, its just that it hasn't been proven.


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## jebatty (Oct 28, 2011)

Try it. I didn't believe it either. A Master Electrician and state electrical inspector showed me this, and I could not believe the result. I have used it since. Do I bet my life on it? No. But it's one more tool in the route to safety.


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## Trail_Time (Oct 28, 2011)

Conduit for me.  It is cheap and offers additional protection should you ever need to dig near the wire.


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## semipro (Oct 28, 2011)

jebatty said:
			
		

> Try it. I didn't believe it either. A Master Electrician and state electrical inspector showed me this, and I could not believe the result. I have used it since. Do I bet my life on it? No. But it's one more tool in the route to safety.



I have tried it and will again.  I'm just saying its never been substantiated scientifically.


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## firefighterjake (Oct 28, 2011)

jebatty said:
			
		

> Try it. I didn't believe it either. A Master Electrician and state electrical inspector showed me this, and I could not believe the result. I have used it since. Do I bet my life on it? No. But it's one more tool in the route to safety.



I have . . . never worked for me . . . unless you count the fact that the stick kept pointing towards the refrigerator.


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## mayhem (Oct 28, 2011)

I would not consder doing anythign other than running outdoor-rated wires buried in conduit and buried to the right depth.  Take photos of the trench before you backfill it so you can refer to them in 10 years when you really want to know where that wire is.


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## mrfjsf (Oct 28, 2011)

If you have any ideas of ever running more than one power wire up to your shed, bury 2" conduit and you'll be golden should you ever decide to run additional wires. If you plan to run one wire and one wire only and never run anything else, just bury UF and be done with it.


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## daveswoodhauler (Oct 28, 2011)

Conduit is cheap enough to buy...would do the same, as I am also looking at bringing power to my shed.


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## nate379 (Oct 29, 2011)

It's cheap enough, but say that for a whole project and a person can WAY over budget.


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## btuser (Oct 29, 2011)

20' trench vs 100' trench would be my determining factor.  100' would probably be cheaper to run conduit.  20' would not be so bad to do it over again(not that conduits can/will break underground).  If I was going under a driveway I'd run conduit and 2 spares.  If I was tucking along a foundation for 20' and then digging over I could see myself tempted to use some of that 200' roll of UL cable I've had for 10 years and never used, but every time I get the trench dug I just end up using conduit.


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## Flatbedford (Oct 29, 2011)

My neighbor who is a NYS licensed Electrician said that when I run power to my barn he will use steel conduit. He feels that this is the best and safest way to go. Now all I have to do is dig the trench and come up with the money to pay him.


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## btuser (Oct 31, 2011)

I'd only spend the money on steel if I couldn't get deep enough. Maybe for sweeps(if you can get away without expansion joints) but that's a.lot of work. Why not backfill with flowable concrete as well?


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## begreen (Oct 31, 2011)

Flatbed, why would you use steel conduit instead of schedule 40 pvc? One rusts and weeps over time and costs a lot more, the other doesn't. This seems like a no-brainer. I wouldn't think twice in this situation.


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## lukem (Oct 31, 2011)

If you have an "in" with the local power company, a lot of times they have "scaps" of direct burial with built in rodent shield metal mesh.  Might be worth a shot...their scraps can are usually pretty long....


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## Flatbedford (Oct 31, 2011)

BeGreen said:
			
		

> Flatbed, why would you use steel conduit instead of schedule 40 pvc? One rusts and weeps over time and costs a lot more, the other doesn't. This seems like a no-brainer. I wouldn't think twice in this situation.



That's what the pro said to use. I'll ask about PVC when I actually get around to doing it.


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## btuser (Nov 3, 2011)

lukem said:
			
		

> If you have an "in" with the local power company, a lot of times they have "scaps" of direct burial with built in rodent shield metal mesh.  Might be worth a shot...their scraps can are usually pretty long....



Those days are long gone.  Once the front office found out about the weekend beer money those scraps anything over 10' goes back to the shop.  I'm being asked to have guys cart back worthless coax "just in case".  Just another table scrap that used to go to the underlings that's now seen as revenue by the boss.


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