So recently a friend had told me about a weird problem they’ve been having with their lights and AC units. They said that one night, some, and only some, not all of their lights suddenly stopped working, add well as all of their AC units. This happened for about an hour, before everything magically started working again. This has never happened before, that say. What could this be?
Bad electrical connection somewhere. If it’s multiple lights on different circuits and multiple AC units (which I assume are on different circuits) then it’s probably dropping a phase, which means the problem is most likely at the breaker box (could be a main breaker going bad or a bad connection), the meter or the meter’s base, at the pole or transformer, or any of the wiring along that path.
Tell your friend to have a qualified electrician look at this ASAP. Worst case, the connection overheats and causes a fire and people die. This isn’t something to mess around with. It needs to be fixed NOW.
Agree with ECG.
Your friend needs an electrician in his house, like, yesterday. If he understood electricity and had a working knowledge of of home wiring he might be able to poke around and tighten some loose connections and get this cleared up on his own. However the fact that ‘half of the lights and all the ac units stopped working’ didn’t mean anything tells me he doesn’t know anything about this type of thing…which is fine, most people don’t. But more importantly, this is too big of an issue for him to start poking a screwdriver at.
As ECG alluded to, your house/apartment has two hot wires (and a neutral and a a ground). In all likelihood, one of the hots dropped out. This is why half the lights are gone, as well as half of everything else (he just noticed the lights). Also the AC uses both the hots so they don’t work at all. Also, anything else that runs on 220 won’t work. So an electric stove, electric water heater etc. Until this is fixed, I’d suggest not even attempting to run any large appliances since they may still try to run and may end up breaking.
As for the electrician, like ECG said, worst case scenario, it’s a loose connection which can spark and start a fire if it’s in the building. Best case scenario, it’s a bad circuit breaker (but that doesn’t sound right).
Your friend could, just for kicks, call his local utility company, since it’s the weekend. They may be willing to come out and check everything from the pole to the meter and verify that that’s all good, even before an electrician checks the inside.
Something simpler to check before spending all that money:
I bought a brand new dryer I couldn’t really afford, because the old one would only dry the clothes intermittently. It wasn’t until after I had the dryer in place and IT failed, that I realized that the fifty year old circuit breakers in my house needed replacing. It only cost ten bucks to buy the one the dryer was on, and I replaced it myself.
It’s certainly possible that his main breaker has a problem that it’s intermittently dropping one leg.
But the reason I suggested calling out an electrician is because, personally, I don’t feel that someone that doesn’t know that “lost half of lights and all ac units”=“problem with one leg”, should be attempting to swap out their main breaker (or any breaker).
If someone mentioned a problem with an outlet or switch, I could walk them through swapping out that (especially if the box wasn’t crowded), but this is a job that’s already big, already potentially creating a dangerous situation and if it’s anything beyond a loose screw or a bad main breaker, already will require the utility company to come out (which is why I suggested possibly calling them first to see if they’re willing to check their side).
The difference here is that you had a bad breaker for one circuit. If the OP’s friend has a bad breaker it’s for the entire house. Which means that the lugs to tighten the screws are hot all the time even when the breaker is off and swapping it requires having the meter pulled (or working with very large, very hot wires that have a mind of their own).
As others have mentioned, the cause could certainly be outside the house. It’s not terribly unusual to lose H1 or H2 (the “hot” legs) at the transformer supplying the house or somewhere else on the utility company side of your service meter.
If this is the case, no amount of work inside the house will help.
I would suggest the following course of action:
Check to see if the house circuits that went out are on one side (i.e., left or right) of the breaker panel. In other words, if the circuit breakers are labelled properly, can they tell if the failures were basically on one set of breakers or the other. If they were, that’s an excellent indication that they lost either H1 or H2. (This is not infallible, as two-pole breakers on one side will actually draw from both H1 and H2.)
If it’s clear that they lost either H1 or H2, then the problem is either outside the house, in the cabling from the meter to the breaker panel, in the main breaker (which handles both H1 and H2), or within the breaker panel (e.g., the bus bars running inside the panel).
I’d start by calling the utility company and telling them you lost a hot leg. They will come out and check the local transformer. It may be that they find the transformer is running hot or has some other issue. No charge, if this was the problem.
If it’s not, an electrician is probably a good idea.
In my experience, the majority of the time this will turn out to be on the utility company’s end. Nothing more required.
While there have been some breaker panels that had all of line 1 on one side and all of line 2 on the other side, it is much more common for the breakers to be interleaved. In other words, as you go down the breaker box, the breakers alternate line 1, line 2, line 1, line 2, etc. and a 240 breaker just takes up two slots so it gets both line 1 and line 2. If you lose one hot line, the failures will be in every other breaker throughout the entire panel and won’t be segregated to the left or right side of the panel.
Good point. A lot of them are actually designed so BOTH H1 and H2 are available on each side, with the double-poles connecting to both.
So, forget what I said and just jump ahead to the “it’s probably the power company’s problem” part.