Tell me how electrical wall outlets can go dead w/o tripping a circuit breaker. Hidden fire danger from short?

More details about the situation in the subject line:

I had three outlets, all along one wall, suddenly go dead.

It happened when I had a shop-vac plugged into one of them, which suddenly quit sucking.

No biggie, I unplugged the vac and plugged it in to another one out in the hallway.

Yet, when it came time to flip the tripped circuit breaker back to the on position, I didn’t see any that had tripped.

Is there maybe a short in the wall that could start a fire?

Or what else could account for this?

The admittedly not-quite-accurate sheet of paper taped to the breaker box door giving me some indication as to which circuits are powering which outlets and appliances in this 110-year-old house door gave me some idea to about which breakers to manually trip to the off position and then flip back on again.

I did that to 3 breakers. Did not fix the problem. Will I have to do that to all 30 or so other ones, or will a tool like this help?

  As an electrician, I wouldn’t even think of trying to diagnose this issue from a post on an internet forum, without being able to examine the situation firsthand.

  You’re going to have to hire an electrician in your area to look into this.

  And no, the too that you indicated will not help, here.  I have that exact tool, and can tell you that it only works on circuits that are live.  Using it is also a bit of an art.  It’s not something that a newbie can expect to use and get a definite answer from, even in the circumstances to which it applies.

Depending on the location of the plug, there may be a breaker in the bathroom power fixture that may have tripped. 1% chance that this is it, but won’t hurt to look.

Yeah, my first guess would be that those outlets are downstream of a GFCI outlet that tripped.

Off-topic just a bit, but when we first moved into our then 60-year-old house 40 years ago, I spent the better part of a day tracing all the circuits in the house. I made a diagram and hung it by the breaker box. It’s come in handy about a thousand times or so.

I did something similar: a CAD drawing of each floor of the house, and near the location of each switch or outlet, I put an “S##” or “O##” annotation, where ## is the number of the breaker supplying that device. Laminated at Kinkos, and hung by the breaker panel. If you’re really anal-retentive, then you put actual numbered stickers on each outlet or switch, but that’s more than even I want to do.

If you don’t feel comfortable doing this, don’t. But here’s what I would do if I didn’t see a tripped circuit breaker and didn’t suspect a GFCI receptacle:

  1. Remove circuit breaker panel.
  2. Grab a quality DMM and set it for 600 VAC. Connect one test lead to neutral or ground. Use the other test lead to measure the “output” voltage of each 15 A and 20 A circuit breaker. (I would probably just measure them all, including the ganged 240 V ones.) Each should read around 120 VAC. If any read 0 V or close to it, try cycling that circuit breaker. If it (visually) appears to be on, but there’s no voltage, then the circuit breaker might be faulty; install a new one. If the new one immediately trips, then there’s a short somewhere. If the new one doesn’t trip, and it has 120 VAC on its output, then the old breaker was faulty.
  3. If the circuit breaker is tripped, you need to find the fault. That’s a bit more involved - you’ll have to start pulling receptacles and whatnot.

Again, do not do any of this if you feel the even the slightest bit uncomfortable with it.

Broken vacuum.

How old is the house, and who did the wiring?

You cannot always tell when a circuit breaker has been tripped. Just like a computer, the first thing to try is turning everything off, wait a bit, and turn it all back on again. If you have a breaker tripping it should make it easier to find.

Once you have turned everything off, apply the same power load as when the thing went out, the three outlets that went out are probably all wired on the same circuit.

The three outlets are probably wired in series, so all are drawing power for the same load where there should be only one drawing power, there are three.

Your brother-in-law didn’t offer to save you money by wiring it himself? Or did you do it?

When I don’t see a tripped breaker I try manually switching it off and back on because they don’t have to move far at all when they go off and you can’t always tell just by looking.

I would almost bet money that the wire feeding the dead outlet has a loose screw or connection on the wire feeding it. That would cause all the wires downstream of that to go dead. Shop vacs pull a lot of amps and it probably gave a good arc when it lost the connection. I t may not be a short just an open circuit.

When I saw the thread title, my first guess was a tripped GFCI.

When I saw that it happened when you plugged in a vacuum cleaner, I updated that guess to a tripped AFCI, or Arc-Fault Circuit Interrupter. AFCIs offer more protection than GFCIs, but at the cost of being more prone to false trippings, especially when motors are plugged into them (because most 120V motors will arc to at least some degree).

Do you have aluminum wiring?
Also. Safety wise. I have a rubber mat in front of my breaker box. I always wear insulated gloves when poking around in it.

Aluminum wiring can develop an insulating layer of oxidized material. It is dangerous in many cases. My friend had me troubleshoot a faulty outlet. It was partially melted. The connections had been arcing. Heating up badly. I showed him how to update his outlets to account for the aluminum wires.

Probably the outlets are daisy-chained using backstab connections. Notorious for failing with vacuum cleaners. One failed connection will take out everything downstream of it.

A short is highly unlikely - symptom for that would be a tripped breaker that refuses to reset.

110 old home. That means someone rewired the house. The fact that you have circuit breakers rather than fuses means it was probably done after 1950. Do you have ground wires going to your outlets. That will move the date up even more probably after 1970(?). So do you know who wired and when?
When I suspected a tripped breaker and could not see it in the panel. I would lightly run my finger down each breaker. Lightly pushing the breakers to the tripped position. If on was tripped when I ran my finnger past the tripped breaker it would move to the off position.

As as many have said if who ever rewired dasiy chained the wires through the outlets you probably one of two screws in the back of the 1st outlet come loose. The proper way to wire outlets is to put a short pigtail on the outlet and then properly wire nut the hot wire in, host wire out and the outlet pigtail all together.

Wow. Great answers everyone. Thank you all very much.

I’ll sift through the advice in the posts and craft a longer response, plus try to reply to some of the questions you all posed seeking more info about the situation.

However, I’m traveling soon and won’t have much time to devote to this for a while.

In the meantime, it’s good to know that it’s probably not a dangerous short.

Our house is only 30 years old, but I spent a Saturday doing something similar a few years ago when I discovered the labels on the breaker box were woefully inadequate. A label might say “kitchen” when it was really part of the kichen plus one wall in another room. Or, as we found out when my wife bought a plug-in hybrid, the garage outlet is on the same breaker as the bathrooms. (The breaker would trip if her car was plugged in and she tried to use a hair dryer at the same time.)

I have a somewhat related question: I have two outlets (along the same wall if that matters) where only the top outlet has stopped working. I assumed a loose connection (and will call an electrician when I can) - but could it be anything else? House is fairly new (2010)

Yes, if you know which breaker, turn it off then on. Often a tripped breaker might bearely move.

I also recall reading that another problem with aluminum is that it was softer even than copper, so more likely to deform over time creating a loose connection (aggravated by that oxidation).

The old trick for loose connections was to take a small transistor radio on AM, tune to dead air, and wave it near the outlets. If an outlet has a loose connection, there will be a noticeable increase in static near it.

But the most direct way, if the breaker is definitely not tripped, is to open the outlets, starting with the one nearest the breaker panel, and see if it even has 120V.

Same here. Either that or an open circuit (broken wire, etc.).