The 3 phase aside, Sparky could be on to something.
Some older houses have circuit breakers for the individual circuits, but fuses for the main. If you blow one fuse, weird things happen. Everything on the other half will be fine. If you have any 240 circuits, power will feed through them into the other buss. It will be reduced voltage, dim light and who knows what electronics will do. As you turn things on and off or thermostats kick on and off, the low power will come and go. The first time I ran into this, it took me a loooong time to figure it out. The second time it took me longer to get my friend to shut and show me the fuse box, than to verify the problem. The third time, I was a little slower, and when I did figure it out, nobody was open that carried 250 amp fuses.
Usually the fuses are in a plastic block that pulls out. Once out you need to do a continuity check if neither is obviously burned. You can always try a new one if you don’t have a meter. Note, be very careful to replace fuses with the same rating.
Most homes are wired from a single split phase. It’s a center tapped transformer and the center tap gets a physical connection to earth ground. The two outer legs of the transformer are your two hots, and the center tap is your neutral. You end up with 120 volts from either line to neutral, and 240 volts from line to line.
Some homes end up with two phases of a three phase system. In this case, line to neutral is still 120 volts, but the line to line voltage is only 208 volts. This type of wiring is not very common these days, but you still find it in some older systems and in dense areas like New York City.
If about half of your outlets are out, chances are you’ve lost one of your lines, and could have a problem anywhere from outside the house to inside the breaker box. You can also lose a bunch of outlets that are all on one circuit by having a fault anywhere alone the line. You can lose multiple circuits if one of the neutral connections inside the breaker box fails. Some breaker boxes have multiple neutral bus bars which are then connected to the box’s main neutral, and a corroded or otherwise faulty connection to these bus bars can make many outlets fail or become a bit flaky.
If you lose the earth ground connection or the neutral connection from the box you can end up with a floating neutral, which gives you symptoms like thelabdude described because your entire house then ends up being a voltage divider between the two phases.
The types of problems being discussed in this thread are the worst types possible since they can easily cause your house to burn down. If you don’t know how to fix it yourself, call an electrician ASAP.
Mom called me about an hour ago. The people from our power co-op came out to look things over. They found something wrong at the pole and at the main box for the house. Like Sparky812 said, I probably blew one of three coming in. Hopefully, this is the end of it. Thanks for your help. Sometimes it’s easier and faster when the workers show up if you already have some idea what might be wrong.
Oh, and to clarify, all of the power for that section of the house was cutting out, not just the outlets.
Residential service won’t have 3 fuses. As I said, some older houses have 2 main fuses. If one blows, you have strange things happening.
Glad to hear you had some professionals come and fix the problem. If it was only a blown main fuse, most home owners should be able to fix that themselves.
There must have been a really funky connection at the pole and/or in the breaker box for an accidental short on a 15-amp circuit to cause a phase to cut in and out like you describe.
Congratulations - your goof with a broken light bulb may well have prevented a previously unknown bad connection in the service entrance from getting hot enough to start a fire.
I’m still wondering if the branch circuit breaker was under-sensitive, to allow the event to be passed out to the utility’s equipment, if that’s really what happened. But it sounds like an electrician has looked into the house panel now, so I’ll trust he’s got it.
Thanks **ecg, **I knew this… I just couldn’t describe it properly.
Glad I could help.
… takes a bow
I’ve seen it quite a few times.
My guess would be an overloaded panel and the fuse simply blew before the breaker could. Fuses are more reliable in that regard.
I’ve seen homes where the main fuses are 80A and there is a 100A panel running off it.
Or homes with 100A service requiring almost twice that.
This is simply not true… although you need to know what you are doing, be aware of the hazards, and follow saftey regulations, there is no reason the homeowner cannot open, inspect, or test your disconnect or breaker panel, etc…
On the other hand, an occupant should contact the owner for any service or repairs.
Secondly, you cannot inspect or test your main disconnect or fuses elsewhere, you must test where it comes into the house.
Finally, it’s gone unsaid but you would turn off the disconnect before opening or working on the fuses.
how many inexperienced people know the layout and construction of a disconnect or a breaker/fuse box. which parts are live metal and which parts are not? which conducting metal belongs to what; it does little good to take voltage measurements in the wrong places (the same conducting metal or the other phase conducting metal).
i said
that is true for owner or occupant.
your statement
i would think that if you were ‘experienced and skilled’ as i said, then you would ‘be aware of the hazards, and follow saftey regulations’ as you said.
and you can see if one phase fuse is blown at other places besides your fuse box if you take careful measurements and know the wiring layout.
I largely agree with johnpost. The average homeowner shouldn’t be removing the cover of a breaker box and messing with the innards it covers. I do feel fuse boxes are OK. Often the fuses are mounted in a plastic housing that pulls clear out of the box. Even the boxes that you must open the disconnect before the cover will open still have hot parts. Even the worst dolts should know to leave them alone.
Note, I have felt capable to have made extensive changes in my main box. They were done so with the main breaker off. That does leave a couple of recessed screws hot where the service wiring goes in. I wouldn’t advise anybody but professionals to mess with the main breaker or the wiring to it. I haven’t seen a fused main entry for a while, but I think they always have a disconnect before the fuses. Believe me, the time I changed the 250 amp fuse, I had the power off and I didn’t get near the contacts above the disconnect.
Yes, because the sum total of all the 15A and/or 20A breakers exceeds the 80A fuses at the main.
Even my own house was wired had a 100A breaker panel and 100A fuses, yet the wire gauge coming into the house is only rated for 80A.
When I discovered this, I immediately swapped them for 80A fuses which is adequate for the size and demand of my household.
I will cede that not everyone should open their breaker panel or disconnect without proper skills/knowledge.
Since it falls within my profession, I am more comfortable and familiar with such things.
FTR, any work I do is with a permit and is inspected by my electricians and the electrical inspector.
dude,
check outlets that are affected by the power loss. used to be there was no requirement for “pigtails” in receptacle boxes, so the lazy electrician would just stick the wires in the holes in the back of the outlet. the problem lies there typically. if there is an in and an out wire plugged into the back of the receptacle, and there is a short circuit down stream from there, a lot of times what happens is the connection between the in and the out gets all crudded up. the way to fix the problem is first make sure that you have the circuit breaker off for the affected receptacles. than what you need to do is to twist the hot wires (Black) together and add a short wire to go to the receptacle which will land under the brass collored screw where the wires are all twisted together, screw a wire nut on tightly. now do the same thing with the white wires and the single wire lands on the silver screw of the receptacle. if the receptacle looks trashed, it probably is so replace it as well. tuck the wires back in the box turn the power back on at the circuit breaker and see if there is any more problems --if so go through the same with any other affected outlets. good luck and be careful
I’ve seen 20-amp breakers hold with a dead short and an upstream 50-amp breaker pops.
Some breakers are just faster than others. IIRC, the 50-amp breaker was a Square D “QO” (Quick-Open) feeding a sub-panel filled with “universal” breakers on another floor. (The typical GE/Westinghouse/Murray/Bryant things that look like Square D “HOM” breakers.)
All the outlets I have seen have 2 brass and 2 plated screws. No need to pigtail if you are only feeding one other device from an outlet. Connect the incoming wire to one screw, and the outgoing one to the the other. Do the same at the next outlet.
No do not do this, you are looking for trouble. The only time I daisy chain outlets is in a 4 gang box. Any high current incidents can cook all the up stream outlets.
If a down stream out let is pulling enough amps to heat the outlet but not tripp the breaker the screw clam can get hot and the plastic of the outlet weaken. This will also happen to all the upstream outlets. I have repaired many outlets that have had cooked wires under the crews.
If the in wire, out wire, and the pigtail are properly twisted together and then wire nutted or crimped the connection will not over heat. The only damage is the one overheated outlet not the whold leg.
Who cares how many other circuits there are? If a short or overload is downstream of this branch breaker, that’s the one I want to pop.
Right. That’s more like what I was getting at with breaker sensitivity in post #9. QO are good. Siemens are good. GE are crap. Not just for speed; I’ve seen some of them just holding current over their ratings. (Didn’t leave it like that.)
in new wiring in most of the USA general appliance circuits are 20A. old wiring could be 15A for these circuits.
most receptacles are 15A devices. Daisy chaining these using the screws or backstab (NOOOOO) will decrease the current capacity. it is a common method in the older wiring.
Glad I could help.