Running buried power out to my garage

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  #1  
Old 08-02-12, 02:44 PM
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Running buried power out to my garage

I've remodeled my garage and want to run power out to it. It is about 30 feed from my house.

To save some money, I'm planning to have my electrician just do the tricky parts (hookup to the panel) and I'll run the line myself.

He said I can just put it in PVC, buried 18" deep from the house to the garage.

Anybody have any other thoughts on what I should do here, to be sure I do this right? I'm not trying to cut corners (just save some money), just want some advice on anything else I should do.

Kind Regards
 
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Old 08-02-12, 03:05 PM
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Are you going to run a single 20 amp 120 volt service or a 20 amp multi-wire 20 amp service or a subpanel? What loads do you plan on having?
 
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Old 08-02-12, 03:12 PM
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Make sure it's schedule 80 PVC and not sprinkler pipe (eg class 200 or sch. 40).

Pull individual THHN conductors rather than bundled wire like UF. Don't pull any bare conductors or bare ground wires.

Some people prefer to use galvanized conduit underground since they feel it gives better protection against an errant shovel. I find that metal conduit corrodes and fills with dirt/rust, making it impossible to ever pull new wire through the conduit. 18" is deep enough to protect from errant shovels.

If you think you might ever want to pull more circuits to the garage, make sure your conduit is large enough to accomodate those circuits.

Mod Note: Only one feeder is allowed to the outbuilding. If more circuits are desired a subpanel on one feeder would be needed. Additional circuits could not be pulled.

Make sure you use long radius sweeps to transition from the risers to the horizontal run. Nobody likes pulling 30' with elbow fittings on each end.

Mod Note: pull fitting must be accessible. The cover is designed to be removed when pulling the conductors and re-installed afterwards. The cover needs to be accessible, not buried.

Oh, and seriously, call before you dig. The liability for hitting a utility line is almost as bad as the potential death involved.
 

Last edited by pcboss; 08-03-12 at 12:17 PM.
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Old 08-02-12, 04:11 PM
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Make sure it's schedule 80 PVC
Actually schedule 40 PVC Conduit is okay except in special circumstances.

Some people prefer to use galvanized conduit underground since they feel it gives better protection against an errant shovel. I find that metal conduit corrodes and fills with dirt/rust, making it impossible to ever pull new wire through the conduit.
Agreed. There are three standard types of galvanized conduit. The thinest wall, EMT, is not recommended for outside burial. The other two require threading and are not that easy to work with. They would not be needed for a job like this.
 
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Old 08-02-12, 05:22 PM
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Thanks everybody. To answer some of the questions posed back to me.

It would be mainly a couple of lights and an outlet or two for the occasional power tool, but now that I'm thinking about it, I suppose it would be nice to plan ahead in case I ever want to use beefier power tools when I retire and build a small boat in the garage

Sparky, what is considered a long radius sweep for a transition? I was sort of thinking of pulling the wire as I bury the PVC -- hadn't thought about any future pulls but thanks for the suggestion, and the thought of making it large enough for future use.

Thanks everybody, I appreciate the feedback and suggestions!
 
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Old 08-02-12, 06:41 PM
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I was sort of thinking of pulling the wire as I bury the PVC -
Big no-no. The solvent cement can damage the cable. You could try running a string through as you assemble it.

If you have a good electrician these are the questions he should be asking you.
 
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Old 08-02-12, 11:28 PM
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Ah thanks for the tip regarding the solvent (I don't see how to quote a response in this forum).

Yeah... maybe he isn't that great -- one of the reasons I'm asking here.
 
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Old 08-03-12, 07:23 AM
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This is a fairly easy DIY job that can be done by you if you want. We can walk you through it.
 
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Old 08-03-12, 08:13 AM
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I'd go with an elbow with a bend radius of 3x to 6x the diameter of the conduit.

Im not sure if you were planning to put a subpanel in the garage at this point but it's worth serious consideration. That way, you could just pull a few, larger conductors and distribute them at the subpanel as your needs grow over time. In my humble opinion, all garages should have at least 50A 240V service, but that's because I like those "beefier power tools" and you never know when I might finally buy a plug-in hybrid truck.
 
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Old 08-03-12, 09:37 AM
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Sparky,It is in my opinion too early to discuss fittings. You'll just confuse the main issues and basics that need to be established first.
 

Last edited by ray2047; 08-03-12 at 04:21 PM.
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Old 08-03-12, 11:43 AM
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Once the decision to use conduit has been made it is never too early to discuss what fittings should be used. The answer is NOT what sparky has been writing but to use ONLY the standard electrical conduit fittings. These have the proper radius so no calculation is necessary.

The ONLY time that you would calculate a radius is when using metallic RIGID (or Intermediate) conduit AND you were bending it in multiple shots with a hickey. Using standard conduit benders would always ensure the proper radius. Non-standard bends are only used when necessary because of aesthetics or non-moveable obstructions in the conduit path.
 
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Old 08-03-12, 03:26 PM
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I can only add these suggestions:

Run at least 1" for the PVC. Larger if you're run anything larger than #10 THWN.
Keep it down to 2 - 90 degree bends. You can make a long sweeping curve for the horizontal run.
EMT is not rated for direct burial.
Electrical PVC is gray in color and found in the electrical dept.
 
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Old 08-03-12, 07:48 PM
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This is the same thing im doing, but you can only run 1 wire to a detached garage, so im running a 6/3 line (waterproof stuff in 2" Grey Conduit) and (using a 50A or 60A Breaker) to a subpanel, because its not code to run more than one line or something. Confusing... I still dont see why running some 12/3 and 14/2 underground. Electrical is easy, its the code that makes it hard...lol
 
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Old 08-03-12, 08:22 PM
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Actually a multi-wire circuit using 3-conductor (+ ground) can provide two 20 amp circuits but only counts as one feed.
 
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