Line flicker--Line loss

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Line flicker--Line loss

Post  rcdallas on Thu Apr 12, 2012 11:35 pm

I want to pick to apart and overthink it a little bit. Let's say you have about a 350' #2 AL service @ 120/240. With no load you are getting 123/123/246 and as you start to put load on one leg you start off with 20 amps the voltage drops to about 120 and voltage on the other leg goes up to 124 and as you increase all the way up to 80 amps the voltage dips to 114 and 128 on the other leg.

Typically if you see a neutral problem you might see something like 80 volts 160 volts; If you check the amps 80 amps on the line side coming in you should see 80 amps going back out and you have confirmed 80 amps is making it way back to the transformer.

Add in a flavor again 123/123 with no load and as you put load 80 amps it goes to 114/128 and at the transformer while under load you are seeing 123/123. So the next thing you might think a bad connection in between; while this maybe true why would the other leg go up to 128 and you have again confirmed your seeing a perfect return on the neutral. In addition when you put the burden on the other leg it does the same exact thing--the voltage flip flops.

Now to overthink a little more could some of this be a ghost reading on your digital voltmeter like when you do a pre-meter install checking line to load if the breakers are turned off you see around 5 volts, sometimes more sometimes less. If that is the case.....

What do ya'll think with what is given--I'm thinking ghost voltage and a combination of too small of wire.

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Re: Line flicker--Line loss

Post  admin on Fri Apr 13, 2012 2:44 am

I don't think so.... I have seen the almost exact same senario many times. I know what your saying about the amperage finding its way home, but in this case I thinks its a classic neutral problem. In fact you may look at the crimps and see perfect aluiminum to aluminum crimps and think to yourself they look perfect, no way thats the problem.
use your fluke and start right at the channel. the key is to pull as much load as possible. My superbeast can only pull about 20 amps, if you can pull 80 amps or more it gets even easier. If you see that voltage swing at the channell move to the weatherhead. if its bad at the weatherhead move to the service pole. Work your way back to the transformer. at some point, hopefully you'll find 123/123/246. Now replace the neutral connection between where its good and back towards your source.
When you finally find that bad crimp use the fluke and check voltage across the connection, I bet you'll see potential accross the crimp. It could even be a bad spot in the service! Maybe a tree used to be there and was cut down a few years ago? who knows? Maybe at somewhere the neutral is rotten down to the steel core. At night you can even see an arc if you take a small piece of wire and jumper across the bad crimp .

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