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Mike G.
Mike G., Master Electrician
Category: Electrical
Satisfied Customers: 7090
Experience:  Proven Professional 46 years Experience
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What is the correct way to transition from direct burial

Customer Question

What is the correct way to transition from direct burial cable to an above grade box? I think conduit is required from the box to 18" below grade. Do I just run the direct burial wire in the conduit and not worry about sealing between the conduit and wire
where the wire enters the conduit below grade?
Submitted: 11 months ago.
Category: Electrical
Expert:  Mike G. replied 11 months ago.

Hi, I'm Mike G and I'll be assisting you. With PVC conduit from the box to 18inch below grade you'll need to have an expansion coupling on the conduit. In the trench a 2 ft loop of wire is required for ground movement.

Customer: replied 11 months ago.
Can you point me to an "expansion coupling"?
Customer: replied 11 months ago.
What I'm looking at for "expansion coupling" looks like something used to join two pieces of conduit--that's not my situation. I just have direct burial wire in the trench now. I have box mounted on post. I can add conduit and whatever to get from the wire from the bottom of the trench up the post and into th box
Expert:  Mike G. replied 11 months ago.

Any home center or electrical supply house will have them. All it is, is a slip fitting that allows the stub up movement preventing pulling the junction off its mounting.

Customer: replied 11 months ago.
I see now. Expansion couple looks like a good idea, though it must not be required for code in our area, since I don't see one used for the service entry to our house or out building. Say I used one, then should I worry about sealing between the conduit and wire where the wire enters the conduit below grade?
Expert:  Mike G. replied 11 months ago.

Sealing isn't required. Your other installations may have been done before expansion coupling were required.

Customer: replied 11 months ago.
Ok, off to get the expansion coupling. Is 3/4" conduit ok for the 4 wire, #10 wire, direct burial cable?
Expert:  Mike G. replied 11 months ago.

Yes.

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