Mistake wiring my new shop


Old 12-05-04, 06:43 AM
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Thumbs up Mistake wiring my new shop - PROBLEM SOLVED!

I have built a new workshop in my backyard and I am trying to get power out to the building. I had a contractor install a new subpanel on my house so I would be able to run an underground cable to take the power across the yard. I needed 100amp service in the shop, so I used four wire 1/0 underground cable to run from the subpanel on the house to another subpanel in the shop. After digging a really long trench (OK it's not that long, but it sure felt like it was) I put the cable in the trench, made sure there was plenty a both ends to attach to the panels, and then I buried the cable. Now I am looking at the wires and guess what, only one is marked (it has a green stripe on the outside). The other three wires are all the same. How can I figure out which wire is which without digging everything up!

Last edited by timinalabama; 12-13-04 at 01:02 PM. Reason: Problem solved
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Old 12-05-04, 07:02 AM
Join Date: Nov 2004
Location: CA
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Buy 100 feet of inexpensire single conductor wire like 16ga THNN. Use that with an ohmmeter to ring out the wire.

If you have an electrician do the hook-ups, he can probably take care of this. He may have a tone-check device to ring them out.

Last edited by 594tough; 12-05-04 at 07:04 AM. Reason: add para. 2
Old 12-05-04, 07:19 AM
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Ok, I think I understand. If I connect the smaller wire to one end and the meter to the other, it will register an Ohm reading on the wire it is connected to .... right?
Old 12-05-04, 07:53 AM
Join Date: Sep 2000
Location: United States
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Or just connect it up to the panel at one end and use your voltmeter on the wires at the subpanel end. Or use the ground wire in the trench as that 100-feet of wire you were advised to buy. There are lots of ways to do this.

However, I'm concerned. If you don't already know how to figure this out, it seems likely you don't yet have the electrical skills to do this complex project. I encourage you to do some further study on electrical theory before proceeding.
Old 12-05-04, 08:14 AM
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If you don't want so much voltage and amperage potentially flowing through you, you could alway connect a car battery to one and "test" the line with your hand/voltmeter/unsuspecting neighbor. Just kidding.

The best way to test it would be a volt meter, the second best would be to buy one of those proximity testers you can put in a plug that light up to show you live. You can actually put those right next to power lines and it will indicate power. Of course nothing should be hooked up to the main panel if you try this.
Old 12-05-04, 09:21 AM
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Join Date: Aug 2001
Location: Maryland
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Ringing out the cable.

Here are the steps to "ring out" the cable.
Strip two inches of insulation off of one end of the cable's conductors.
Connect the black side of your cars battery jumper cables between the conductor with the green tracer and the wire opposite it while looking at the cable's end.
Connect the red side of the battery jumper cables to the two conductors that are right beside the wire with the green tracer.
Take your meter or any other continuity tester to the other end of the cable.
Check between the tracer conductor and the wire opposite it while looking at the cable's end.
You should have continuity.
Check the adjacent conductors to be sure you don't have continuity to any adjacent conductor.
Check for continuity between the two wires that are right next to the one with the green tracer.
You should have continuity.
Mark the conductor opposite the one with the green tracer with a white tape band at each end.
If the results don't come out as I have predicted let me know.
Also let me know what the makings on the cable jacket read. I suspect from your description of it's conductor marking that it will be some form of SE.
Tom H
Old 12-05-04, 02:53 PM
Join Date: Sep 2002
Location: welland ontario
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Just connect 2 of the cables together at one end. Go the other end and find which 2 are connected with an ohmmeter. The other one is the one not connected at the other end. Use that for your neutral and the 2 connected ones for the hots. It doesn't matter which is which for the hot.
Old 12-13-04, 12:58 PM
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Thumbs up Thanks for all the help

Thanks to everyone for all of the help and advice. I was able to successfully ring out the cable, and get it connected properly to the new panel in the shop. I may only have one circut complete, but it is grounded properly and nobody got shocked! Thanks again for the help, and I will be back the next time I need advice.

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