# Lights dimming



## jwjrw (Jan 14, 2010)

Nope the light in my kitchen does it sometimes do to poco voltages. I cant believe they agreed to replace the trans for that.


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## LGLS (Nov 10, 2007)

A loose neutral between the panel and the transformer can cause this, as well as someone else's loose neutral.

This occurs at a house I rent out that shares a transformer along with a few other houses and the Long Island Railroad - they have electric track heaters and apparently electric heat in a communications shed that causes all the houses to dim & brighten as the heaters cycle on and off. Long Island Power Authority is not so generous with their transformers in this case.


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## toolman001 (Apr 12, 2008)

*Lights Dimming*

This happens when the small equipment starts such as microwave, frig,wine cooler blower motor on furnace (gas)


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## toolman001 (Apr 12, 2008)

This is the only house on this transformer


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## drsparky (Nov 13, 2008)

Sound like the power company has the answer.


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## BCSparkyGirl (Aug 20, 2009)

mine do it when the microwave is on..........stupid 1978 wiring


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## LGLS (Nov 10, 2007)

toolman001 said:


> This is the only house on this transformer


If this is the case, and something on L1 is causing voltage to fluxuate on L2 then the neutral is definately the problem. I don't know what the smallest pole pig is, but I doub't there it can't handle 1 house.


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## MDShunk (Jan 7, 2007)

Because of the disparity between L1-N and L2-N voltages, I think it's safe to say that you have a loose service neutral someplace. Don't let the PoCo tell you otherwise. Don't leave the jobsite until you're personally talking with the PoCo's trouble man while he's on the job. There's a definately a loose neutral someplace. Could be in the main panel, the meter base, weatherhead taps, or transformer terminals. Here lately, I've had a run of three of them that had the aerial triplex neutral darn near rubbed through by tree branches. Call the PoCo yourself, tell them you're an electrician, tell them you have an open neutral, and tell them you'll be waiting for the trouble truck. PoCo's tend to take open neutrals pretty seriously when it's an electrician that puts in the work order. Unless they're tied up with storm damage someplace, they usually come right out in less than an hour.


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## toolman001 (Apr 12, 2008)

Thanks this confirms what I suspected I have checked the neutrals in the box and meter base.


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## MDShunk (Jan 7, 2007)

toolman001 said:


> Thanks this confirms what I suspected I have checked the neutrals in the box and meter base.


One reasonably good way to confirm your theory is to load one leg with a 120V resistive load, like a space heater or hair dryer. If that leg's voltage to neutral goes down, while the other leg's voltage to neutral goes up, you're hunting an open neutral.

If you put a heavy 240 volt load on the panel, like an electric oven broiler or electric baseboard heat, and the L1-N and L2-N voltages become closer to each other, that also means you're probably hunting an open neutral. 

With a good neutral, your L1-N and L2-N voltages should be within a volt or two of each other. Even with a severe imbalance of the 120V loads, seldom will you observe more than a 3 volt disparity in a dwelling. Occasionally, you'll see one leg's voltage go down, while the other leg remains unaffected. That means you're hunting a loose hot connection, and the neutral is fine. If the load on one leg affects the other leg, that always means there's something up with the neutral.


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## toolman001 (Apr 12, 2008)

This is just what I wanted to get this input. What a great resource thanks to everyone who replied to my post.


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## Priority Electric (Jan 10, 2010)

Loose neutral connection


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## jw0445 (Oct 9, 2009)

If it's aerial don't overlook the SEU cable. I've run into the neutral being corroded from water intrusion to the point it was causing the imbalance.


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## Dennis Alwon (May 9, 2009)

This is behaving as a classic bad neutral. Replacing the trany may not be the answer but rather checking the connections of the neutrals.

I had a situation where the HO said the same thing. I diagnosed a bad neutral. The poco came out 3 times each time insisting that everything was fine on their end. I finally called the engineer and explained the issue. He said it was a classic bad neutral. I told him to get his guys to fix it-- they did- they finally pulled apart some connections rather than just using their meter. 

Most of the lineman don't have a clue about troubleshooting. You have to stay on them.


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