# lights get brighter when we run our compressor???



## Alska101 (Dec 31, 2008)

ok here is the problem. we roll in the the customers house to do some trim and plug in our compressor and start it up the lights in that room get brighter!!! and the compressor is laboring and will not run like low power. ok we move the compressor to another plug on another circuit (the frig, plug) and the compressor still will not run it just labors and the lights then dim. so we pull out the plug tester and walk around the house and test every plug and they are all good wired right! all have about 115-120v. we even shut off all circuits and just left on the frig. plug and still cant run a compressor even tried three other compressors. and one is little thing.


what could this be i had a electrician in and  no fix. we even ran new ground wire and added a new ground rod. still have same problem.



help!!!!!!


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## 480sparky (Feb 1, 2009)

Hire an electrician who can find an open neutral in the service.

NOW.

Before things start burning out.


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## neolitic (Apr 20, 2006)

480sparky said:


> Hire an electrician who can find an open neutral in the service.
> 
> NOW.
> 
> Before things start burning out.


Learn me somethin'.
Shouldn't the circuit where the
lights get brighter be a clue as to
where to start looking?


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## 480sparky (Feb 1, 2009)

neolitic said:


> Learn me somethin'.
> Shouldn't the circuit where the
> lights get brighter be a clue as to
> where to start looking?



An open neutral will cause voltages to go up and down, depending on the load impressed on both legs of the system.

Click here.

To give you an example: Here's two 100w lamps in series: One lamp is 'seeing' 120.4 v, the other 127.18.










Here's a 60w and the same 100w lamp in series: Note the voltages:












As for where to look, if the problem manifests itself everywhere, it's in the service.


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## neolitic (Apr 20, 2006)

Cool.

I ran into something like in an
unoccupied house.
I plugged in and a bunch of lights 
suddenly came on.
Unplugged, and they went off.
I just used a utility outlet that 
came right off the panel, 
and I could see how it was wired.
Told the owner to call Sparky, but
I wasn't around for the end of the movie.


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## woodchuck2 (Feb 27, 2008)

I agree with 480 on this. It wont be long until devices begin burning up. If someone cant find a neutral problem from the meter to the home then load test the line side of the meter to see if there is a problem with a transformer.


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## Static Design (Nov 30, 2008)

480 you like Fluke Meters like me


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## griz (Nov 26, 2009)

Even my old nail pounding butt has a couple of Fluke meters:thumbsup:


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## Ohmy (Sep 10, 2009)

Fancy Fancy Sparky


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## s.kelly (Mar 20, 2009)

Gotta know 480, did you rig the demo for this thread, or was it from something else?

You are such an overachiever, but it makes you great to have on a forum!


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## 480sparky (Feb 1, 2009)

s.kelly said:


> Gotta know 480, did you rig the demo for this thread, or was it from something else?
> 
> You are such an overachiever, but it makes you great to have on a forum!



I took them for another thread on another forum.


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## EES (Jan 4, 2010)

neolitic said:


> Learn me somethin'.
> Shouldn't the circuit where the
> lights get brighter be a clue as to
> where to start looking?


No. It could be a poor connection on the neutral of a multiwire circuit, the neutral at the panel even on the lines or under ground. Sometimes it can only be a problem when under a load, or under a load over x amps. A similar problem can be when your have a fused main or an old main breaker that loses one phase and backfeeds 120v to the other phase through 240 volt equipment creating series parallel circuits.


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