Underground circuit.


  #1  
Old 07-20-00, 10:53 AM
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I am running a 110v circuit out to my in the back yard. I have seen the grey pvc schd40 at Home Depot. Is this what I should use?

I do not want to run the underground rated romex, instead I want piping. The grey pvc sold in the electrical department does not look as watertight as the pvc for water, that is why I ask. Also, to be safe, I am thinking of running indoor romex thru the piping instead of single wires off a spool. I want to do this as a precaution because I am not a professional electrician. Does this sound like a safe idea?

How deep should I bury it in Missouri? I'm not asking for city codes, etc, just a professional opinion.

Mark

[This message has been edited by Mark Chapman (edited July 20, 2000).]
 
  #2  
Old 07-20-00, 12:18 PM
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As I understand it, the grey PVC for wire and the white PVC for water are pretty much the same thing. The only reason they have different colors is so that you can tell what it is when you dig it up.

So why don't you be extra safe and run underground rated romex inside the pipe. The cost difference isn't that much.

I'm not an electrician either. How about an unprofessional opinion? I'd bury it at least a foot deep, just to get it out of shovel range. Actually, I overdo everything, so I'd probably even bury it even deeper.
 
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Old 07-20-00, 01:25 PM
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Per UBC - direct bury - 24", Rigid/IMC - 6", Nonmetallic residential (120 volt 20 amp max.) - 12".

Personally, I would use pvc buried atleast 12" deep, with sand backfill for part of the depth. The sand makes for a better bedding of the conduit and gives the next guy a clue that there is a conduit there.

As for wiring, use solid #12 THHN, it is rated for use in conduit. I would not use romex inside conduit, because it would be very hard to pull through the conduit and the insulation is not rated for use inside conduit. Be sure to include a ground wire and use a GFCI outlet or circuit breaker.

As for the pvc conduit, 1/2" is all you need. Use the "gray" glue and assemble just like irrigation pipe. It is not really a problem if there is any water in the conduit, as long as no splices occur in the water.

 
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Old 07-20-00, 04:01 PM
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hello mark,
i am an electrician. what u want to do is buy the 3/4 " gray pvc conduit easer to pull then 1/2" and glue it togather with pvc glue no need to prime bary this at a depth that will provide at least 18" of cover this is per the national electric code(i allways go 24 to bottom of trench). im assuming this is a 20 amp circuit; then run 3 # 12 thhn wires threw it 1 black 1 white and 1 green id pull stranded rather than solid easer to pull. u can not run regular romex under ground even if its in conduit its insulation is not rated for under ground.
 
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Old 07-21-00, 02:16 PM
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Thank you all. I have purchased the 3/4" pvc and will bury it 24" inches this weekend.I also bought the stranded wire instead of solid. I appreciate everyones advice, and especially from Sprky, the electrician. My only goal in life for the next 48 hours is to eat, sleep and lay that new circuit underground at all costs!!! Let nothing get in my way!! Thanks all.

Mark
 
  #6  
Old 07-26-00, 09:15 AM
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I have finished the job now I am very happy with it. The 3/4 " conduit worked good for getting the fish tape leader with 3 #10 wires thru. Boy that can made a big knot on the leader.
I had trouble connecting stranded #10 wire to a duplex receptcle screw. I wished there was a better way. The strands want to fray as you bend and tighten the wire to the screw.

I was also concerned about using those red twist-on tap connectors to connect solid #10 to stranded #10. I kept wondering if it was a good connect or a frayed connect inside that cap. I never worked with stranded before, so let me know if it is wrong to
connect stranded to solid, because I will go back and redo them if I have to. Better safe than sorry.

I only had 1 weak pvc joint where the pipes overlaped 1/4 inch instead of one inch. I hope that keeps the water out. I was just to hot and tired and low on parts to correct it.
If water gets in that weak spot, laid underground, will it be safe?

Mark

 
  #7  
Old 07-26-00, 05:48 PM
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Hi Mark,

Just a couple of things about your work.
First you didn't need to use #10. But since you did, two options are available to get them to work on a 20 amp or 15 amp receptacle. You need to pigtail #12 to the #10 then on the receptacle. Or, you can use stak-ons. The fork variety and insulated. To use these you need more room in the box because you shouldn't bend the stak-ons.
Also, in the future, when you need to pull any wire via a puller, strip back about three to four inches, then cut most of the strands off and loop back halfway through the stripped portion. This way the total loop is not much larger than the group of wires you're pulling. Tape it tightly and it will hold nicely.
The wire caps are OK. You can mix solid and stranded. Just make sure you twist so that the wire begins to twist in your hand holding the wire.
You won't keep water out of the pipe anyway, so don't worry about it. That is why you use THHN which is water rated. You can also use THW which is rated for water or underground.
The main purpose of keeping the pipe together is so you can either pull in or out wire.
 
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Old 07-27-00, 07:25 AM
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Wow, Thanks. You addressed every question I had. I love the tips you gave me. It is easy for a do-it-yourselfer to do poor work and then NEVER know it was poor. I like knowing when a job is done, whether is was done right or not. So thanks again for all the help.

I may have misled all when I mentioned my wire sizes. I was just keeping it simple to
write in the forum. Acually, I ran #10 half way down the run, to a pool pump outlet, then changed over to #12 from the pump on down to the shed in back yard. The entire run length up to the shed outlets and lights, comes to 125 feet or more. So I used the #10 to keep my voltage drops to a minimum at the shed, due to the lenght of run.

This is a great forum and you guys are great for giving your time to everyone here. Well, now my electrical project is official and successfully complete.

Mark
 
 

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