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wild voltage fluctuations between 120 lines in breaker box.

wild voltage fluctuations between 120 lines in breaker box.

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  #1  
Old 09-09-11, 01:35 PM
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wild voltage fluctuations between 120 lines in breaker box.

I live in a small town in Mexico. For the past week we've been having large voltage spikes. I've been troubleshooting with a digital voltmeter. There are big differences between the two 120 lines in the breaker box. One side will shoot up to 167-171 volts and the other will drop down in the 40's and sometimes it will reverse it's self. If I flip the main switch and turn it on again sometimes it will normalize to 120 on both sides. When I turn off the main switch and check the lines coming from the meter I get a stable 123 volts on each line. When I turn on the main switch with the voltmeter still connected the voltage from the lines to the meter drop and raise to what ever the house is pulling. I've gone through each of the breakers and noted the voltage fluctuations. I can raise or lower the voltage of a line by turning the breakers on and off. At one point I had all of the breakers turned off except for the outlet for the fridge. When I checked the outlet it was 120 volts. I kept the voltmeter plugged into the meter and then plugged in the fridge. The voltage dropped from 120 to 43 and popped back up to 120 when I unplugged it in again. The breaker box is grounded with a rod driven into the ground and connected by a copper wire. Some of the newer wiring is 3-wire (has a ground wire). Parts of the house are 2-wire (no ground wire). I'm 63 and worked a good many years in construction so I'm somewhat familiar with the basics of household wiring. There are no electricians here and the guys from the power company show up with 1 pair of rusty pliers. We are had a new transformer put in 4 years ago and are the only ones hooked up to it. I have the power stabilized right now but have most of the circuits turned off including the fridge. Sure could use some help. Thanks
 
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  #2  
Old 09-09-11, 02:28 PM
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Welcome to the forums! Don't know if we can help with the Mexican power fluctuations, but it appears you have a floating neutral/ground somewhere. If you have a local power company, call their emergency number and have them look into it. They could also have a bad transformer leg. Just something to look for.
 
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Old 09-09-11, 03:26 PM
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I've been troubleshooting with a digital voltmeter. There are big differences between the two 120 lines in the breaker box.
That statement confused me. If it is wired like in the US there should be no 120v lines. There should be two lines with 240v between them and a neutral which is ~0v to ground and 120v to either leg of the 240v. Is your house supplied with 2 wires or three wires?
 
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Old 09-09-11, 04:26 PM
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I think the OP is seeing the flucuations between the two hot legs while under load.
 
  #5  
Old 09-09-11, 08:31 PM
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Open neutral. You're goinna have to call the poco's emergency service asap.
 
  #6  
Old 09-09-11, 09:08 PM
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Well I did it myself. I eliminated circuits until there was one outlet. Both lines showed 120 volts. I plugged in the fridge and the voltage dropped off to 42 volts and around 160 on the other line. I decided it was time for a closer look at the transformer. The ground wire was burnt in two. Lightening got it. The power company guy came with his pliers ans twisted the cables back together. I'll find a better way to clamp it later.
 
  #7  
Old 09-09-11, 09:15 PM
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Woops I didn't see the comments posted above my first comment. It's a little different format than some forums. The combined voltage of the 2 lines(legs) is 240. There are 3 wires, a ground and 2 hot wires of 120 volts each. Justin and Chandler you were both right on the money and thanks.
 
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