137 volts


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Old 05-30-08, 10:44 AM
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137 volts

We just bought a new house and I am grounding all the ungrounded outlets in the place. But I see that the standard voltage readings at the receptacles is around 137 volts.

Why is this so high, and is this a problem? We just had a new service put in yesterday, but the reading was that way prior to the new service, and I was unable to ask the electricians while they were at the house.
 
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Old 05-30-08, 11:16 AM
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How are you measuring the voltage and with what type of tester? Does each receptacle measure the same, or are some lower? Also try testing the voltage with a lamp plugged in to the other half of the receptacle and turned on.
 
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Old 05-30-08, 11:33 AM
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Also try your volt meter at the house of a friend who lives a few miles away or borrow another meter.
 
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Old 05-30-08, 11:39 AM
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And are you measuring hot-to-neutral, or hot-to-ground?

137 is too high, significantly too high. There are many reasons, however, why your measurement might be incorrect, and we can only hope one of them applies.
 
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Old 05-30-08, 12:27 PM
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I am not in the house now, and have no internet access there at the moment. But I am headed over there later and will try the lamp idea.

I have been using a commercial electric multimeter. There were no ground three-pronged outlets in the house, but I originally tested from hot to neutral of course (137 v). Once I ground the outlet I get 137 from both hot to neutral and from hot to ground.

I can't say that I have tested every single outlet, but all the ones I have tested are the same: 137.

I am hoping this is a meter issue.... Time for a new one maybe. I will test it out at the neighbors when I go over there again.
 
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Old 05-30-08, 12:50 PM
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So far it sounds like your testing procedure was okay. If the reading is the same with the lamp plugged in and turned on, then a call to your power company is likely in order. The maximum voltage you should see according to spec is 127V, nominal is 120V.

If (and only if) you're comfortable working in the main panel...remove the panel cover and measure the voltage on the incoming feeders right at the top of the main breaker. Test hot-to-hot and each hot-to-neutral. Take the measurements both with the main breaker on and with the main breaker off.
 
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Old 05-30-08, 12:58 PM
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Ok. So I will do the lamp test and the meter test at a neighbors this evening. If it is the meter I will throw it away. If it is not, then I will call the power company.

But is there an immediate danger as a result of this? Like I said we're not living in the house at the moment, but I am spending time over there working.

Thanks
 
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Old 05-30-08, 01:13 PM
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No immediate danger until you start plugging things in and start using the power. It is high enough that it could damage some of your electronic equipment. Good thing to get it fixed now before you move in. You may want to keep any appliances off as well.
 
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Old 05-30-08, 01:26 PM
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Also, check at more of your outlets. If you can read 137 volts at some, perhaps you'll read 103 volts at others. If so, that will be a very important clue.
 
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Old 05-30-08, 01:31 PM
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I'm wondering how you are grounding the outlets. Are you running new cable to each outlet or are you running a single wire that grounds it? If the latter, I don't think that is allowed by NEC. A pro can provide more expert opinion on that issue.
Good luck with it all.
Bob
 
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Old 05-30-08, 02:03 PM
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I suggested testing at a friends house some distance away because it might be a problem with a local transformer. Neighbors house if the problem is on PoCo side might show the same thing. Move away a few miles and you can get a true test of the meter.
 
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Old 05-30-08, 04:34 PM
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Originally Posted by John Nelson
Also, check at more of your outlets. If you can read 137 volts at some, perhaps you'll read 103 volts at others. If so, that will be a very important clue.
If it is, i just fixed one almost exactly like that today. They put an H-tap sleeve on the neutral out on the pole, and never squeezed it down. Been that way for probably 80 years and finally started to act up .

nova_gh
master electrician
 
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Old 06-04-08, 04:09 AM
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Thanks for all the responses everybody. I tested my meter at a neighbors and got the same reading, which got me wondering about a transformer problem. He then dug out his old meter (maybe 35 years old) and got about 130. So, ok. Now we were really wondering.

We went over to a different neighbors who has a new meter and tested all our houses. We got 120 all around. So I am guessing my meter (as well as the neighbors) need to be replaced. I'll buy a new one this week and test again.

Thanks again.
 
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Old 06-04-08, 10:06 AM
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Well if you want to go a bit deeper into reasons you might look here:
http://www.ece.unb.ca/tervo/ee2791/vrms.htm
 
 

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