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I just did a job for a customer where the lights in his house will actually get brighter when a motor or a load is turned on. And it can happen from any circuit in his house. What is actually happening is some how voltage is jumping from phase A to Phase B in his panel. I tried everything I know and still cant fix this problem. I know it has to be a neutral somewhere but want to ask my fellow electricians out there for some help. Do you think it is a problem with the power company's neutral in their transformer or in this guys house? Thank you
 

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Discussion Starter · #2 ·
Also I have tried to isolate every circuit in his panel but even when I only leave one circuit on the lights will still surge if a motor is turned on.
 

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What kind of motor are you turning on? Is it 120V or 240V?

Doesn't sound like a neutral problem unless some of the lights are getting dim as others are getting bright.

Sounds more like one of the legs is loose/damaged and when a 240V load is turned on, it's back feeding to the side with the bad leg.

Have you checked the voltage at the panel? Also, have you checked the current draw on the whole service and the circuits that are effected?
 

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Discussion Starter · #4 ·
We were using mostly a normal vacuum cleaner to test. Nothing 240v . So are you suggesting I try and change the 2 hot legs going from the meter to the panel? I did make sure they were tight
 

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Power Company, seen similar symptoms before.... Loose or broken grounded conductor somewhere 'tween the main panel and service drop. Can be difficult to locate. OH or Under Ground?
 

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3 possibles to consider -

1- Bad/Loose neutral, Usually will cause other circuits to rise. any syptoms ?

2 - Bad loose connecttion causing current limiting ! *most common*
call electrician.

3 - Power grid cannot supply any more power cause overloaded.
*also common* Call poco !
 

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I just did a job for a customer where the lights in his house will actually get brighter when a motor or a load is turned on. And it can happen from any circuit in his house. What is actually happening is some how voltage is jumping from phase A to Phase B in his panel. I tried everything I know and still cant fix this problem. I know it has to be a neutral somewhere but want to ask my fellow electricians out there for some help. Do you think it is a problem with the power company's neutral in their transformer or in this guys house? Thank you
1. Identify a receptacle on phase A. Label it receptacle A.
2. Identify a receptacle on phase B. Label it receptacle B.
3. Turn off all breakers except those serving receptacle A and receptacle B.
4. Unplug everything in the house.
5. Plug a 1800W heatgun or microwave oven into receptacle A.
6. Plug a 40W incandescent into receptacle B.
7. Plug a voltmeter into receptacle B.
8. Turn on the heatgun and the light and watch the meter.
9. If you see a voltage exceeding 130V across the bulb then measure between phase B and neutral in the service panel. If you see the same high voltage then it is either a power company problem or neutral is disconnected or burned in the panel.
10. If you see the correct voltage then the problem is in the house.
 

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Power surging

If your service drop is an older one, might even give your power company transformer a good look over from the ground. Service drops can deteriorate, insulation breakdown, even pieces come off and bleed over to bare ground/neutral. Crazy that it doesn't always trip the primary jack. But seen it more than once. Voltage will pulsate or dim out. Open all breakers on one phase or the other. Use to have some pictures of broke down service drops that would scare the s*&t out of home owners, transformers burnt but still in service. Stay safe and inspect often.
 

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I would say neutral issue for sure. I had the exact same symptoms on a service call yesterday. Both phases in the panel read 120v to neutral, yet when load was applied to either phase individually, there was no amp reading on the neutral. However, I could read total amp draw on ground wire. Called Poco and they came out and fixed neutral at transformer.
 

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E
1. Identify a receptacle on phase A. Label it receptacle A.
2. Identify a receptacle on phase B. Label it receptacle B.
3. Turn off all breakers except those serving receptacle A and receptacle B.
4. Unplug everything in the house.
5. Plug a 1800W heatgun or microwave oven into receptacle A.
6. Plug a 40W incandescent into receptacle B.
7. Plug a voltmeter into receptacle B.
8. Turn on the heatgun and the light and watch the meter.
9. If you see a voltage exceeding 130V across the bulb then measure between phase B and neutral in the service panel. If you see the same high voltage then it is either a power company problem or neutral is disconnected or burned in the panel.
10. If you see the correct voltage then the problem is in the house.
Sounds like a neutral issue for sure
But sometimes the fault can lie with pocos eqipment
So check your system first and if you cannot find the problem
Then you might have to call poco !
 

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When a utility transformer is weak it can do this. We wired a new home and it did just this. Replaced the tub and was good to go. It would show equal voltage to neutral, but would pulse every 2 to 3 seconds.
 

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In my old city at 5:30am the lights would dip as the hydro damn wound up for peak supply. Dont think it happens anymore though.
 
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