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HouseBoy

03:16PM | 02/17/05
Member Since: 01/13/04
4 lifetime posts
Bvelectrical
I bought a bench grinder at Ace - it ran at about 10 rpm,; I could stop it with one finger. returned it, took a replacement, had them demo it in the store - worked fine. Took it home - same as the other. Tried several circuits. Had the electrician who wired the house come out - he says house is fine; power from street is 136v - too high - that's why I'm burning out light bulbs, and the grinder got fried as soon as plugged in.

House is less than 1 yr old.

Does this make any sense?


rpxlpx

08:33AM | 02/18/05
Member Since: 03/13/00
1675 lifetime posts
You should now call the power company. If the voltage they provide is really too high, they should fix it.

HomerS

03:40PM | 02/19/05
Member Since: 03/20/04
24 lifetime posts
What you described is not a normal situation. It is highly unlikely that the power utility is supplying "too high" a voltage.

It is much more likely that you have what is refered to as an "open neutral" condition. This is extremely hazardous. The problem may be on your side of the line (main panel) or it may be on the utility's side(meter can or transformer).

When there is an open neutral condition the 240V between the two HOT conductors is not split evenly between neutral (white). One leg of the service may be above 120V while the other is below 120V. This difference will depend on what loads you have connected on your circuits.

Since your electrician only quoted the voltage of one of the two legs (136V), and came to the conclusion of utility overvoltage, I suspect that you need to have another electrician take a look. If he said that the voltage between the two legs was 272V then I would believe his diagnosis.

If you really do have an overvoltage from the utility, the voltage between both legs of your service would be much greater than 240V.

A call to the utility to look at the problem may not be a bad idea. They may find that the problem is on your side and you may need to find a knowledgeable electrician to fix the problem. If it is an open neutral condition it needs to be addressed immediately as it will damage appliances and they may catch fire.

If you are unable to measure the leg to leg voltage yourself then you should call another electrician or the power company to figure out the problem.

Homer


HouseBoy

05:11PM | 02/23/05
Member Since: 01/13/04
4 lifetime posts
Thank you for your thorough reply. I did call another electrician - the first thing he asked was "did he measure both legs?". In fact, he had said he had - I didn't state that in the original post as I didn't understand the distinction. I got the power company out - they showed up within 20 min of my call! They read the voltage at the meter as 123 on both legs. So I pursuaded them to go inside and read it in the breaker box - 122 each leg. So I got the original electrician back out, who brought his "better voltmeter" (ha!) and read 122; had him check out the outlet where I'd connected the grinder - 120 v. He checked the connections - no loose neutral wire.

So I was back to square one. I managed to find a device I bought years ago to check outlets for reversed hot/neutral, open neutral, etc. It has leds to indicate ok.

I checked the outlet, and then I checked all three plugs of a 3-way extension cord I had leading to my workbench. 2 outlets fine, the third had an "open neutral" indication until I wiggled it around a lot.

Yes, that is where I had plugged in the grinder!

Could it have somehow "found neutral" via the ground wire, taken a jolt, and gotten fried? The open neutral SHOULD just make it not go, shouldn't it? Is there a scenario whereby this was all a false alarm - house wiring ok, street power ok, flaky extension cord and (oversensitive?) cheap grinder?

Does THIS make sense? Was I alarmist then, or am I being too cavalier now?


HomerS

10:18AM | 02/27/05
Member Since: 03/20/04
24 lifetime posts
It looks like you don't have an Open Neutral on your service but just on an individual circuit.

You asked, "The open neutral SHOULD just make it not go, shouldn't it?"

If your circuits are all wired as 2-wire circuits from the panel to the receptacles then the answer would be yes.

However, it is possible to have what is know as multiwire or shared neutral circuits with 3 wires (2 hot and 1 neutral). If you have an open neutral condition on a multiwire circuit the results would be what you've witnessed. You would see one leg of the multiwire circuit above 120V while the other is below 120V depending on the load on the two legs.

I guess you need to look at how this problem circuit is being powered.

Homer


Charlie53

04:18PM | 02/26/07
Member Since: 02/25/07
2 lifetime posts
What should the voltage be coming into the breaker box? 120v +/- how many volts? I am now living in a 30+ year old house, It blows light bulbs all the time. Never seen anything like it. Bulbs blow in all the rooms, even the basement.

I have tested the box with a digital voltage meter and seem to have 127 volts on both legs.I also tested some outlets and found them to around 127 +/- votls. What should it be? Is this why we blow bulbs all the time?.....Thanks

TimBonham

02:26AM | 02/27/07
Member Since: 01/09/07
197 lifetime posts
Your voltage is an average -- the power goes in a sine wave from zero to about +150 volts, back down thru zero to about -150 volts, and repeats this 60 times per second.

The average is calculated to be 117.5 volts, ± about 7% variation. So from 109 to 125 volts is about the normal range. Generally, power companies try to keep it in the 115-120v area.

So your voltage does seem a bit high. (Assuming your meter is accurate. Many such meters are designed more for electronic equipment, and DC -- they aren't always the most accurate for utility power, especially if not tested under load.) It might be worth asking the power company to come out and check it -- they should do this at no charge.

P.S. Why do you say "even the basement"? There is no reason for a basement to have any different electrical voltage than any other part of the house!

Charlie53

03:52PM | 02/27/07
Member Since: 02/25/07
2 lifetime posts
Thank you for the quick reply. Your info is a great help. We will get in touch with are power company. As for the basement....just pointing out that the lights are used a lot less and yet the blow out like the rest of the rooms....Thanks again
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