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Electrical Wire Test

Old 05-16-2010, 04:49 PM
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How do we check an under ground 10-2 wire that is 200ft long to see if there is a break--fault? This in on a irrigation system and when we disconnected the wires at the breaker near the pump and left them connected to the main panel, the breaker throws. I really don't want to have to dig and replace 200ft of wire.
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Old 05-16-2010, 04:56 PM
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disconnect both ends of the wire. Wire the black and white together on one end and do continuity test on the other end with a multimeter. There should be a setting on the multimeter that buzzes when the two leads are touched.

Last edited by BigPumper; 05-16-2010 at 05:13 PM.
Old 05-16-2010, 05:05 PM
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Thanks, I am familiar with electrical wiring but not using meters and trouble shooting unless it is trail and error.
Old 05-16-2010, 06:17 PM
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Big pumper nailed it. Just make sure you unhook it from the main circut breaker first.
Old 05-16-2010, 06:24 PM
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But if the breaker is popping when you turn the circuit on, you might want to try and do the continuity test with the wires just disconnected.

What does the circuit run? Try disconnecting it from whatever it runs and then turn it on..... If the breaker pops then, the wire is bad. Dont forget to wire nut the end of the wires when you disconnect it from whatever it runs.
Old 05-16-2010, 07:31 PM
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If you need to locate the fault , you need a time delay reflectometer--and someone who has one and knows how to use it.
Old 05-17-2010, 04:25 AM
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Do it right and get hold of a megger
.....http://www.testequipmentdepot.com/me...t200series.htm
Old 05-17-2010, 05:09 AM
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You could also try disconnecting the wire from the breaker and see if it still throws. Breakers can go bad and are easy to replace.
Old 05-17-2010, 06:11 AM
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If continuity tests to zero, or close, then wiring is OK.

As jrolin1 said, you could switch the breaker with a known other breaker of the same rating and see if things stay the same. That means that your breaker is OK.

Your next test is the pump motor for an overly high starting draw; indicative of a failing motor.

If you aren't familiar with a volt-meter, no worries. Go to Radio Shack or electrical supply house or big box store. Any of their salesmen will be able to spend the two minutes it takes to get you comfortable with using it's most common features (12V, 120V, and continuity testing)
Old 05-17-2010, 01:44 PM
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Step one we replaced the breaker at the main panel with no positive results and then the one at the pump location. Same result, thrown breaker at the main panel. Disconnected the wire from the relay and the breaker did not throw. Took the wire loose from the breaker panel near the pump, hooked it back up at the main panel and it threw again. Took it loose at the main panel and hooked a dummy wire up and it did not throw. Re installed the wire at the main panel and then took the wire loose at the breaker panel near the pump and it threw. This lead me to believe the main wire under ground is bad. Just hate to spend $250.00 and dig another trench.
Thanks for the replies.
Old 05-17-2010, 01:49 PM
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If you disconnected the equipment out in the field so that nothing is hooked to the wires and the breaker still trips your going to have to replace the wire in the ground.
Old 05-17-2010, 05:44 PM
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That's what I thought. Sometimes you just don't want to hear the truth, you know what I mean? $250.00 for wire and a ditch to dig.

Thanks
Old 05-17-2010, 06:11 PM
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Just finished doing that yesterday for underground speaker wire and low voltage lighting. Not much fun. good luck.
Old 05-17-2010, 07:13 PM
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If the wire is underground shouldn't it be in a conduit? If so, what kind, what size? I would think 1" PVC would be the min. Why can't you just attach your replacement wire to the old wire and pull the new wire through......saving you the dig? If you have to buy some fishing lube to lube up the inside of the conduit as you pull your new wire through.
Old 05-17-2010, 08:43 PM
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It could be direct burial, non metalic, wet, underground (NMWU). Repair with PVC conduit might be a good idea with single conductors.(R90)
Old 05-19-2010, 09:06 PM
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FYI, I don't care what type of wire you use , PUT IT IN CONDUIT , We have customers that have VERY electric bills because of Direct bury wire mixed with MOLES AND GOPHERS .
Old 05-19-2010, 09:32 PM
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Listen to Welder!
Old 05-20-2010, 01:05 PM
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This is what you need to mark out then pinpoint the fault location. Of course buying the unit is more expensive then paying to have the trench reopened. Do yourself a favor and place the new wires in conduit, it's cheap and you can always pull a new wire through it if you have problems in the future.


http://multimedia.3m.com/mws/mediawe...6EVs6E666666--
Old 05-20-2010, 01:25 PM
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You can direct bury 10-2 UF but I would install it in gray/ elect PVC.

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