Seems that every few days the electricity wil turn on and off in only 1/2 of my house. For instance this computer I am using will shut down but the computer on the other side of the room will be fine,in the bedroom the lights on one side of the room will go on and off but the tv and radio on the other side of the room are fine,In the kitchen the fridge and stove will turn off but the microwave on the other side of the room will be fine. So i can go on the other computer and I wil just watch my monitor as it goes: off on off on…off…on…offf on…off…on…This can happen some days for up to 10 minutes,then it will all seem ok for an hour or so and then start again…there is no pattern to it,its totally erratic…we called the power company and they told us to get an electrician in here to look at it first,but my husband isn’t willing to spend $60/hour to have some guy sit in our house until it happens cause it can happen within 20 mins or it might be another 3 days…any suggestions?
You basically have three wires coming into your house, line, nuetral, and line. If you measure line to line you get 220 volts and from either line to nuetral is 110 volts. All of your 220 appliances will be connected line to line. Everything else in your house will be wire from one of the lines to nuetral. It looks like you are losing one of the line voltages, so everything that happens to connect on that circuit is dying. The big question of course is why.
That section of wiring is only common from the fuse box on out to the power company’s wiring. You might want to have an electrician come in and check that part of the system out.
There’s three wires coming into your house from the pole transformer. It is a center-tapped 240 V line, with half feeding one side of yoaur breaker panel and half feeding the other, with the common in the center. this gives you two separate 120 V main circuits, plus a 240 V circuit for things like electric stoves and other appliances requiring 240 V. Probably the set screw clamping one leg of the incoming line in the panel has become loose, allowing the circuit to make-and-break randomly. Id don’t recommend you attempt to repair it yourself if you are at all uncomfortable around electrical repairs, but it should only take an electrician a few minutes to fix.
Definitely call an electrician. He won’t have to sit and wait until it happens because he can check the wiring either at the meter or the circuit panel and find the loose wire. If you don’t get it fixed ASAP you’ve got a potentially big fire hazard on your hands.
You don’t mention the age of your house and electrical system. If the house is sufficiently ancient, you might have large cylindrical fuses in your fuse box (much like auto fuses). If these fuses or the clamps are corroded, that could cause the problem (and would be very dangerous because the resistance from the corrosion would be creating lots of heat).
Does the black-out correspond to weather conditions? If the problem is in the outside line (maybe a tree branch or loose connection), then wind might be causing the problem.
I think Q.E.D. and engineer… have it nailed. It is not uncommon for the screw holding down one of the main feeds to loosen from expansion/contraction. But Finagle has a good point. Water can leak into the meter box, corroding the contacts, or even run into the panel, corroding the connections there.
Don’t try tightening these yourself. There’s no way to turn off the power to those wires without pulling the meter. (caveat: one in a bazillion meter boxes have a disconnect, which is a handle you can pull down and stop the current there). Only the Power Company is allowed to pull the meter and if they pull it and leave (in the case where they don’t see a problem on their end but there is one on yours), they won’t put it back without an inspection.
The good news is that you can call the power company, and ask them to come out and check things. They are only responsible for stuff up to and including the meter, but very often, unofficially, the guy will check the main connectors while the meter’s out and snug them down for you. If not, he may pull the meter and you can snug them down while it’s out.
There’s not too many places for this problem to be happening, so it shouldn’t take an electrician more than half an hour to an hour to find the problem.
Before you call an electrician, go to the fuse/breaker panel and hope for a failure while you’re there. Listen for humming, crackling or hissing sounds. Hear any of these? Call an electrician now. Try turning the main breaker off and on a couple times to see if that has any effect.
Problems that would be yours to fix:
Bad connection in the fuse/breaker panel - where the main wire connects to the main breaker, or where the main breaker connects to the “bus” The main breaker itself could be bad.
A bad connection will probably just need a couple turns of a screwdriver to fix. Breakers take about a minute to swap - a “main” breaker probably costs around $50-75, depending on size/type, where it’s bought, and the electrician’s sense of price mark-up on parts.
The utility’s responsibilities:
Bad connection at the pole, bad splice where their wires join with your wires at the house, bad connection at the meter, bad meter.
If you ever encounter lights going dim and others going bright, call the utility immediately and tell them you think you have a “loose neutral” - this is a very serious condition and they’ll probably have a crew at your house within the hour. (What this means is the neutral wire has a bad connection and instead of evenly dividing the two 120-volt lines that add up to 240 volts (120+120=240), you can wind up with something like 100+140=240, or at the extreme, 0+240=240, which tends to result in blown lightbulbs and fried appliances.
It does sound like one of the 2 main leads are not working.
But
the neutral is physically connected to the ground leads inside every circuit breaker box I have seen and the power comapnies only deliver 2 wires to the house, There is no neutral, the neutral goes into the ground. Please tell me what power company actually deilvers a neutral wire to each house!
Also the phases are 120 degrese apart, not 180 - but I’ve heard this is a local NY thing and most of the country is 180 (I don’t know if this is true, but I’ve heard it).
Thanks everyone! I’m gonna show this post to my husband and hopefully it will get fixed in the next week while he’s off work,Don’t worry I won’t let him tackle this one himself! LOL
Recount your wires. There’s 3 wires from the pole unless there’s no 240 V service in your building. I’ve never heard of a power company relying on an Earth ground for the neutral, especially since I’m pretty sure that’s a violation of the NEC.
I’ve never seen a two-wire only feed in North America. All power companies I’ve ever dealt with supply the two hot legs and a neutral. Perhaps you’re missing the neutral as it’s normally bare in a service entrance and the other wires are wrapped around it. You are correct that the neutral wire is connected to the ground wire at the breaker panel’s neutral/ground bus. However, the neutral does not go into the ground.
The teminology is a touch confusing, but how it works out is the “ground” (bare or green) wire is the grounding conductor, and the neutral (usually white) is the grounded conductor. The difference is that the neutral does not have to be at ground potential, and in fact, there are circumstances (such as sub-panels in large buildings or “isolated” power for certain test equipment) where the neutral shouldn’t be grounded. Pretty abnormal for a house, though.
As for 180/120 degree phasing, standard residential power is 180 degrees apart. In commercial and industrial settings, you’ll find three-phase power, which does have a 120 degree separation of phases. Again, this is something I’ve never seen connected to a house.
I’ve never seen a two-wire only feed in North America. All power companies I’ve ever dealt with supply the two hot legs and a neutral. Perhaps you’re missing the neutral as it’s normally bare in a service entrance and the other wires are wrapped around it. You are correct that the neutral wire is connected to the ground wire at the breaker panel’s neutral/ground bus. However, the neutral does not go into the ground.
The teminology is a touch confusing, but how it works out is the “ground” (bare or green) wire is the grounding conductor, and the neutral (usually white) is the grounded conductor. The difference is that the neutral does not have to be at ground potential, and in fact, there are circumstances (such as sub-panels in large buildings or “isolated” power for certain test equipment) where the neutral shouldn’t be grounded. Pretty abnormal for a house, though.
As for 180/120 degree phasing, standard residential power is 180 degrees apart. In commercial and industrial settings, you’ll find three-phase power, which does have a 120 degree separation of phases. Again, this is something I’ve never seen connected to a house.
Guess that gave the hamsters indigestion as they burped it up again. :smack:
Sorry, no electrical expertice from me, but my house has those large fuses. They are mounted on a ‘customer pole’ about 30 feet from my house, directly under my meter. I had the experience you mention, about ten years ago. Only half my house had power, and the strangest thing was when I turned on my electric range from 0 to 350, and the light above my table came on as if it were on a dimmer switch…low to high and back again, as I turned the knob on my range. Water had entered the fuse box and shorted out one fuse. The power company thankfully changed them for me, and I subsequently sealed the box and made it water tight. No problems since then, but I keep extra fuses available.
Well the 120 is a NY thing from what I’ve heard. perhaps so is the BYON (bring your own neutral), but one way or another I am going to find out, even if I have to start my own thread, or even ask Cecil (yea right that will work).
There is unquestionablaay ony 2 wires comming from the pole to my house, the ground and neutral wires are connected to a common buss in the circuit breaker box. That buss is connected to a big (6ft estimate) long spike driven into the ground. there is NO connection to the pole from the neutral.
So I am left with:
1 - the circuit breaker boxes I’ve seen in the LIPA and Niagra Mohalk area are unique and provide their own ground while the rest of the country doesn’t.
2 - you don’t know what your talking about
3 - I am mistaken as to what I’ve seen and just looked at it again in responce to this thread
4 - God is playing tricks on me (again)
Usually the service is going to be like QED described, a single phase 240 V that is center tapped. If the phases are 120 degrees out of phase then they are two phases of a three phase circuit. I’ve never personally seen a house that was wired to a three phase service, but I was told in college that many houses were in fact wired this way.
There wouldn’t be a nuetral if the houses were fed from a delta transformer. I don’t deal with residential power systems enough to know if this is commonly used or not.
I thought that the NEC specified that the nuetral has to be grounded through a copper rod within (some number) of feet from the service entrance in a residential house.
No, they are not two phases fed into a house. The pole transformer that feeds your house is fed from one phase of the 7,200 V overhead line. The transformer then steps this down 20 240 V, single phase, which is center-tapped to provide two 120 V lines and the neutral. The neutral line is the center tap on the transformer secondary.
As I said, this is the most common, but it’s not the only way things are done. I poked around on the net a bit just to make sure I wasn’t remembering things wrong. I found several power companies that only had a distribution voltage of 7200 V, but I also found references to others that ranged from 2400 V to 12,470 V. The 2400 V portion in particular was discussed as having been recently replaced with 7200 V wiring, and it was mentioned that only very old portions of the system had 2400 and 4800 V wiring.
Orange and Rockland Utilities in New York supplies residential service at “Single phase at approximately 120/208 or 120/240 volts.” The 208 system is obviously 2 legs of a 3 phase system, despite the fact that they are calling it single phase, which makes sense because in the wiring it would be treated as if it were just the same as a 240 V split phase. It took a while to find this (I finally had to use “208” as part of my search terms in google and even then most of the hits were for 3 phase service) so apparently these types of systems aren’t very common.
Hmm now that I think about it 208 is only obvious to EE geeks like myself and QED. For the rest of you, the reason it’s obvious is that in a 120 volt split phase system (180 degrees apart) the line to nuetral voltage is 120 volts and the line to line voltage is 240 volts. In a three phase system, the line to nuetral voltage is still 120 volts but the line to line voltage is 208, not 240, and it’s 120 degrees out of phase, not 180. So if your 240 voltage is really 208 and it’s 120 degrees out of phase and not 180, then you’ve got two phases of a three phase system.
Yes, 120/208 V would definitely be a two-of-three-phase system. Line-to-line voltage in a 3-phase circuit is sqr(3) * line-to-ground voltage, or 207.8V for a 120V L-N. I’ve never encountered this in NJ.