QUICK ANSWER PLS concrete over type UF direct bury cable


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Old 04-05-11, 02:38 PM
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QUICK ANSWER PLS concrete over type UF direct bury cable

I'm putting 2 4x4 posts in the ground, set in quickcrete. I'll need to pour the concrete around, next to, and over two pieces of type UF direct buried electrical wire I buried in the same piece of ground last summer. They are 20-amp 12 gauge and a 30-amp 10 gauge cables, two conductors plus a ground, each. Each one is on its own dedicated breaker in my main panel.

I don't know what damage long term contact between concrete and type UF cable insulation would do. Am I risking damaging the circuits sometime in the future? I don't want to do that.

Can I put the concrete right in contact with the cable insulation? I'm willing to immobilize the cables by doing this. Or do I need to move the cables 6-12" to the side to get them out of the way of where the posts need to be (I can, but it'd be a LOT of extra work). Or should I put something in between them and the concrete? If I need to put something in between the concrete and the cables, what should I use? scrap plywood? good ol' duct tape around the cables? saran wrap or tin foil? just kidding...

Thx...
 
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Old 04-05-11, 05:22 PM
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I never like to entomb wiring in concrete. I would relocate the wire or run it through conduit through the concrete. I like using PVC piping for conduit mainly because I always seem to have niblets of it lying around.
 
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Old 04-05-11, 05:47 PM
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Those posts aren't going to last forever in the ground. At some point that concrete will porabably need to be ripped out to replace them. Something to think about.
 
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Old 04-06-11, 06:47 AM
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It might be a good idea to ask over on the electrical forum. An electrician can probably give you the correct guidance.
I would probably try to protect the cable with PVC. Do you have access to slip a slotted length of PVC over the cable?

As for the posts, if you use the right kind of wood they'll last pretty close to forever. If you are using PT wood don't use the off the shelf stuff from one of the home improvement stores. That wood is minimally treated and drooplug is right when he says it won't last long. Look for posts intended for ground contact and try to select posts that are mainly heartwood.

I have PT ties from HD that i used around a flower bed. After 10-12 years they are rotted. I have PT posts imbedded in concrete supporting my deck that are nearly 30 years old with no sign of rot. the difference is in the level of treatment.
 
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Old 04-11-11, 07:11 AM
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2 X 4's are not below ground rated, use a 4 X 4 instead.
That wire was suppost to be a min. of 18" below ground if was then you could pore the concrete over it.
If the wires not 18" below ground then your going to have to pull it and dig deeper or incase it in gray PVC.
 
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Old 04-11-11, 09:11 AM
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What do the wires go to? Is the 30 amp 240 volts?
 
 

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