lights dimming

[Billy D]

I was wondering if some one out there could help me with a small problem.
I have a customer that is complaining that all his lights in the house are dimming when any of his appliances draws power. We have checked all connections to the breaker box, meter socket, appliances, etc., and also had the power company come out and change their connections and the problem is still there.
The customer has since talked with an another electrian and they convinced him that his breaker box was defective.
Well guess what, he stills has the same problem.
I hope I have explained this well.
Thank You

 

[bphgravity]

Re: lights dimming

There may not even be a problem. Whenever a heavier load comes on, a certain amount of voltage drop should be expected. There is a possibility that there are simply too many loads on one or more circuits and excessive voltage drop is occuring only on those circuits.

 

[hurk27]

Re: lights dimming

AS Bryan has said, this can be normal. especially if the feed from the utility transformer is very long. have you measured the amount of voltage drop with a given amount of current at the main service? some states will require the utility to stay within a certain amount of drop. but the utility could charge for larger conductors to be run to eliminate it.

The contractor who said that they needed a new panel should be in trouble. The problem needs to be addressed not part swapping.

 

[dereckbc]

Re: lights dimming

First thing I would do is monitor the voltage and current at the main panel, then switch loads on/off and see what happens. Like as Wayne and Bryan stated, it could be normal for excessive long/undersized service conductors. Once you have some information, you should be able to determine the exact cause.

 

[69boss302]

Re: lights dimming

Are you sure it's all the lights in the house. My father in law complained of this once and asked me what I would charge to upgrade his service. I went over and watched as he started and stopped a mixer in the kitchen. Turned out to be just the lamps in the living room and they were kind of old. Pulled the bulbs out and the contact on the bottom was all mashed (more than usual. Cleaned it and pulled it up a little for better contact. Of course pulled the plug first! Put in new bulbs and his problem went away.

 

[Billy D]

Re: lights dimming

I have recently talked with the owner again and he said that all the lights do dim. We previously have had the power company out there to replace there connections on both ends of the service.
I did find out that the existing breaker panel was an FPE!! So it was a good idea to replace it, don't you think!
I will test the power coming in with out a load and then with a load on it. I agree that you will see some dimming when there is too much of a load on that circuit and you get a quick surge from something starting up, but not the whole house.
Do you thing that if he was the last person on the utility transformer it would do this?
Thank You

 

[pierre]

Re: lights dimming

As has been stated, there can be a multitude of situatins that may cause this to occur.

How many houses are supplied from the transformer?
You seem to have taken care of most of the other reasons that may contribute to your situation, changing the panel may not help - but any time you change out an Federal Pacific panel is a good idea.
They may have to live with this.

 

[charlie]

Re: lights dimming

Keep in mind the electric utility may still be at fault if the transformer is too far from the service and the secondary is too small. Additionally, the load on the transformer matters. A transformer puts out its rated voltage at its turns ratio only when there is no load on the transformer. The impedance of the transformer will cause voltage drop in addition to all the load.

 

[charlie tuna]

Re: lights dimming

i agree with the above post! power companies admit nothing until proven! i had a friend who had a similar problem and it was an overloaded transformer! voltage was dropping down to around ninty volts when his a/c came on. i had to provide them with written proof before they actually took action. the crew that came out to change the transformer told the owner "oh ya, all these transformers are overloaded in this neighborhood"!