Hi all,
I have problem at home. Recently my oven, water heater, dryer.... stopped working. I tried playing with the breakers but it all seems to be fine. One curious thing in the panel is that if I measure the voltage between the 2 hot wires it reads 58volts... if I measure each of the hot wires to the ground it measures 110volts.. is this normal? Should the voltage between the 2 hotwires measure 220V ?
Thanks!
Call the power company. Today.
If your readings are correct it sounds like the transformer at the pole.
Yes, it should read 240 volts. You have one dead leg of the 240 volt circuit coming into the panel. It may be a bad main breaker, or open circuit at the meter or elsewhere on the utility companies end
Since you are getting 110 (should be 120 in most areas) I doubt if it is the power company. I suspect you have a floating neutral and that needs to be addressed as you cold end up with damaged electronics or even a fire. (I had a boss once that burned down his photo studio due to one.)
However since I am not sure of exactly what you are measuring and how, I would suggest asking the power company to come out and make sure their end is OK first.
Note: If you have or can find an old analog volt meter rather than that digital, I suspect you will find that those 54 V measurements will become
0V. In fact if you go now and measure them again you might get something lower or higher this time. If so that is another indication of a floating neutral.If he's measuring between the "two hot wires" he should read 240 volts regardless if his neutral is intact or not. The only reason he would get anything less would be one dead hot leg. When he reads between each hot leg to ground, he reads the good leg normally and the dead leg he gets a backfeed reading through any 240 volt appliance that happens to be turned on. Both will give a 120 volt reading.
If it is truly an open hot leg then surely somewhere else in the house there should be signs of some of the lights not working and some of the outlets being dead. That is just the way the standard North American split 240V system works. I won't pretend to know what it is that the OP is actually measuring or how he is measuring it -- there are just too many variables involved especially if he is using a DVM.
Personally, I would start measuring at the utility feed and then through the bus bars and forward but there is no way I will encourage a non-experienced person to do what I would do. I learned to do much of this while I was still a teenager and credit my continued breathing to an abundance of caution.
Actually, I got to thinking about what I wrote and started to wonder if it is possible to get cross-feeding from one bus through some 240V device into the other bus without enough odd behavior elsewhere in the house to notice. I guess it is possible if one wasn't looking for the symptoms. Probably the best thing to do would be to simply turn off all of the 240V breakers in the panel to eliminate any potential cross-feeding. If it was one dead bus then surely some of the lights and outlets would go dead with all of these breakers turned off.
Has anyone ever seen a half-tripped service main breaker? I haven't, but I've seen it in a few regular 240V ganged breakers and know that they can cause some odd things to happen. It might be worthwhile to simply turn off the main and then turn it back on.
That's exactly why he's getting a 120 volt reading from the dead leg to ground. Lights will work on the dead leg through backfeeds through 240 volt appliances and Edison circuits, (circuits that share a common neutral) but they won't be full brightness
I agree. One of his 240V appliances is on - probably the water heater - and is back-feeding all the 120V circuits on that leg.
Your 120V circuits will each be on one side or the other of the 240V. Assuming you are able to tell which is which, if you turn off all the breakers for circuits on one side as well as any 2-pole 240V breakers, what happens to power on the circuits on the side that remains on?
If the neutral is open then these should be dead as well. But for that to happen you'd also have to have also a missing or bad ground at the panel or maybe your ground is ok but the utility's grounding of the neutral on the secondary side of the transformer could be bad.
However, with a neutral open but a ground that is present but mediocre you might read proper voltage with nothing turned on and even have satisfactory operation of a few lights and other small stuff but severe voltage drop when trying to drive a heavy load.
As the others have said call the utility or a professional electrician ASAP and be VERY careful about coming into contact with ANYTHING including what ought to be grounded. If the neutral is open somewhere and grounding broken or insufficient not only can the neutrals be lethally hot but it's even possible for the grounds to be hot (less likely with conduits although possible depending on physical construction but easily possible if the grounds are just wires within Romex and the like).
I had a neighborhood transformer fail once, with wierd readings and strange symptoms.
one side of transformer fried, still produced a wierd low voltage...........
real bear to figure out....
call power company, as first step
Practically every modern panel is set up with alternating buss, not left side and right side. The few exceptions are obsolete panels like Pushmatic and Zinsco
Wow I wasn't expecting these many answers, Thanks ALL!!
The way I measured the hot wires is I turned off the main breaker and used a digital volt meter, it gives me around 50-58 volts between the hot wires but each of them gives 110V when I measure against the neutral wire. I am having problems with some devices and some lights only turn on
100% if I turn on the oven.That is exactly what happens with one open hot leg. Call an electrician or your electric utility
I saw a half tripped main breaker many years ago. It was a Federal Pacific. I shut it off and turned it back on again and everything was fine.
its best to not use a digital volt meter when doing home repairs, they are way too sensitive..........
cheap analog meters are fine, or put a trouble light 50 watt load on the circuit then check with a digital meter.
a 25 watt light bulb is enough of a load to also let you know whats up, just connect across connection and see if bulb glows
Nonsense. The two hot legs should always have approximately 240V between them. The neutral has nothing whatever to do with that.
According to RBM :
Not necessarily. If one leg's connection to the utility is broken, he could see no 240V devices work, and _all_ of the 120V stuff appear to work. If a 240V device (like the water heater) is switched on, it'll backfeed one 120V side into the other.
Ordinarily, you'd expect the lights on the "broken connection side" to be dim, but if you don't load it up very much, and the 240V device is large enough (water heater, stove, dryer), the lights may well not dim noticably at all.
The voltage difference between the two legs at the panel is the voltage drop across the 240V device.
Simple way to check this stuff out without opening anything up:
1) Cycle the main breaker, and see if things work any better. 2) Turn off _every_ 240V breaker, and see if he loses one half of the 120V circuits."RBM" wrote in news:478152ec$0$9075$ snipped-for-privacy@cv.net:
I didn't mean "side" in the literal sense of how the panel is laid out. We've got one where it's the top group vs. the middle group with mains at the bottom and 240's that straddle top and middle.
Anyway, looks like he's got one hot side open.
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