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Old 03-26-2013, 08:45 PM   #1
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Lights get brighter when load starts?

I was at a friend's house helping him install some track lighting in his basement. We installed LED bulbs in the track lights and connected them up to a dimmer. We were sitting down admiring our handywork when his oil boiler lit up. WHen it started, we were expecting the lights to dim a little, but the LED lights actually got brighter during the momentary surge the boiler made. WHat's up with that?


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Old 03-26-2013, 08:58 PM   #2
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A loose neutral connection some where.

Any other lights do it?
Do some get dimmer as well?


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Old 03-26-2013, 09:04 PM   #3
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Originally Posted by jbfan View Post
A loose neutral connection some where.

Any other lights do it?
Do some get dimmer as well?
Yep....or the transformer is going....happened to us...

Take a voltmeter and measure the voltage at the load center

You need to do the test twice....

Measure from one side to neutral....turn on a heavy load such as an iron....

Repeat the test on the other leg.

If the voltage goes up on one leg but drops on the have a bad connection before you load center or the transformer feeding your house has an issue.

If no significant change (2 volts or less), then you have a loose neutral somewhere in the load center our down stream.

In my case, just turning on table saw cause a 13v rise on one side and 13v drop on the other....the power company replaced the transformer post haste....
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Old 03-26-2013, 09:10 PM   #4
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Classic symptom of a loose neutral.

It could be anywhere from the utility transformer all the way to a 12/3 or 14/3 that feeds the circuit in question.

When a load is applied, look to see if lots of lights brighten or just a few. Some will dim as well. If just about everything brightens or dims, the problem is in the panel, meter base or the incoming utility lines.

If just a few things brighten or dim, it's more likely in a 3 wire cable that feeds the offending loads.

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Old 03-26-2013, 10:17 PM   #5
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Agree classic indication of a loose neutral. Also very good chance of damaging any electronics you have. Unplug anything important you don't want damaged.
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