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BigFZ 10-24-2010 07:39 AM

Troubleshooting strange brownout effect on one circuit
On my bedroom circuit if I plug in a vacuum thats 12amps it causes a brown out in the room. The breaker itself is 15 amp. This circuit is also effecting my fridge circuit and caused the fridge to essentaily brown out as well, but it's on its own circuit. Also the electric stove and water heater as well as the garbage disposal will not work either. If you flip on the garbage disposal it will actually brown out the bedroom light circuit. It does not effect any other circuit in the place just that one. I metered all the plugs and got 120VAC. I also metered the incoming power into the box and both hot leads are 120VAC. If I plug the vacuum into the outlet and turn it on,and I get a reading of 59VAC from the plug in the room and the one associated with the fridge. I switched out breakers and still does it. I'm trying to figure out what would cause this. This problem only occurs on the one circuit and I've ran the vacuum on multiple 15amp circuits without the same result. I've metered every hot, neutral and ground inside the box and I've inspected a few outlets so far and all look good all the connections are solid. This problem started out of the blue and it has me stumped. I'm also wondering if it could be an outside problem. The main breaker is actually outside integrated into my meter, so I don't know if anything could be malfunctioning out there.

AllanJ 10-24-2010 07:50 AM

You probably have a bad neutral. You need to unplug all electronics, televisions, microwave ovens, etc. until this is fixed.

It's your choice whether to call the power company to see if the problem is on their lines or to get an electrician first to see if the problem is on your side, but this work needs to be done yesterday.

By the way, are there any circuits elsewhere in the house that are not affected when you test using old fashioned incandescent lights and also turn the vacuum cleaner on somewhere? That is, the lamp neither brightens or dims or the voltmeter neither rises nor falls significantly from 120 volts?

If some circuits are unaffected then the problem is on your side.

While waiting, you should retorque all the screws and set screws in the breaker panel. (Loosen about a quarter turn and then retighten firmly but not using tremendous strength.) Include the screws on the terminal strips (neutral bus bar and ground bus bar) in the panel.

With the main breaker out at the meter off and no voltage measured anywhere in the panel, you can retorque the big set screws in the panel (unscrew a quarter turn and screw in medium tight three times before final tightening to better clean the contact) yourself, for those eavesdropping and with the main disconnect in the panel itself, leave the big screws for an electrician to do..

BigFZ 10-24-2010 08:14 AM

Thanks for the relpy. It seems to only be affecting the one bedroom circuit, and the fridge circuit. But its strange because the fridge circuit is getting 120VAC but when you plug it in it browns out so I moved the fridge to different outlet and no problems it runs fine. But the stove, water heater, and disposal don't work either and each has its own breaker. The dinning room, living room, and bathroom(which all have their own breakers) are unaffected when I do the light bulb and vacuum test. I'm wondering were and how to start troubleshooting the bad neutral?

AllanJ 10-24-2010 09:06 AM

Are the refrigerator, bedroom, and disposer circuit breakers all on even rows or all on odd rows in your panel? See if the problem happens on other circuits that you have not tested yet.

We could have a loose connection on one of the two main hot lines that form the 120/240 volt electrical service. Circuits using the other main hot line would then be unaffected. All 240 volt appliances will be affected.

(You may need the help of an electrician to figure out what breakers are on what side of the 120/240 volt service, even/odd is not foolproof.)

It is safe to use electronics on circuits that are totally unaffected. Reduce your electrical usage as much as you can and try to use only unaffected circuits. The refrigerator should be moved to an unaffected circuit using an extension cord if needed.

BigFZ 10-24-2010 10:44 AM

The bedroom breaker is on the top right hand and the fridge breaker is the second to last on the left hand side. Can the connection be with the breaker itself to the terminal strip or can be loose somewhere else? The termianl strips are aluminum and I was told to try to clean them up and tighten them up as well. I will have an electrician over tom so I'll update you with the findings, thanks for your help.

BigFZ 10-26-2010 09:08 AM

Got an electricion to come over and check it out. We found that the outisde breaker was in extremely bad shape in fact is badly melted. So I had a dead leg coming into the house.

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