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One circuit in our house is behaving very strangely, and isolating the issue has proven difficult. It's a house built in the late 60s and the electrician who wired this did add what I think is quite a bit to the circuit, two bathrooms and two bedrooms (5 outlets, 6 light fixtures). One of the bedrooms is converted to a home office where I use my laptop on two monitors. There are no GFCI outlets in any of these rooms.

The issue is that all of a sudden we are seeing low voltage (by multimeter test) at the outlets when one or more of the lights is switched on. I can also see this at the fixtures because some of the bulbs are incadescent and they now only operate as if dimmed, and the led lights will cut off completely when I add any load to the circuit.

We haven't really added anything new, although the issue did seem to get a lot worse immediately after I plugged in a 240W power adapter for a new laptop. My daughter confirmed she had seen the lights flicker/ dim the day before, so I think this was starting before I used the laptop, but maybe the laptop made it worse? (not enough electrical knowledge to know why that would be).

I have replaced the 20A breaker, and I've disassembled a few of the outlets and one fixture looking for an obvious culprit. I am going to do this for the rest of the outlets on the circuit, but any pointers re: possible other culprits would be greatly appreciated.

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  • Would be looking for loose or corroded connections. 20amps breakers must have at least 12 gauge wire in the circuit. A 60s house might have mainly 14 gauge which should only be protected by a 15 amp breaker. Would add up all the power used on that circuit, most lights that are on use about 1 amp, the 240w power adapter is 2 amps, so they should not drop the voltage by themselves.
    – crip659
    Aug 11, 2022 at 15:16
  • Check the temperature at each of the boxes on that circuit. If one is a little warmer start there. Power it off, open it and check all connections. If it is not holding plug firmly or if the wires are stabbed into the back replace it, power up and then see if the problem is fixed, if not try again for another plug.
    – Gil
    Aug 11, 2022 at 19:24
  • Practical plan for the answer below: trace the wire path from the breaker and disconnect receptacles in reverse order (end to beginning). Disconnect the lights along the path as well. After disconnecting each segment, see if that fixes your issue (then the issue is in that segment of wire / receptacle / light). Once you have the path you can also replace the first one with GFCI, and the others with new regular receptacles. That's a lot of back and forth to flip the breaker on and off a bunch, but should determine where the problem is.
    – BurnsBA
    Aug 12, 2022 at 14:54
  • When the low voltage happens, are any of the other circuits in the house affected? Lights brightening? Higher voltages? If you start seeing higher voltages on other circuits, you have a problem (lost neutral) that needs fixed ASAP. Aug 13, 2022 at 6:57
  • Problem solved, thank you everyone for the advice. When I pulled the fixture in the basement bathroom everything else went back to normal function. Not going to try to figure out what happened with it, its one of those with 8 separate bulbs and a tangle of wires, I think the previous owner did some work to it before and we'll just be safe and replace. Thanks again! Aug 13, 2022 at 22:38

1 Answer 1

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Sounds like a bad connection.

99.9% of the time, that will be at a device or in a junction box - wire breaks in the wall (away from a device or junction box) are exceedingly rare.

If any of the devices use "backstab" connections, those are highly suspect and a common cause of issues (including fires. The voltage that drops is making heat wherever this problem is.) In the usual case that they also have side-screw connections, you can move wires to those, but if any device is severely heat damaged, it should be replaced. Not unconmon to find the culprit partly melted or charred.

It would not be a terrible idea to purchase 5 new receptacles of decent quality and replace them all. Also be on the lookout for blank electrical box covers that would be on a junction box without a receptacle or switch associated, to open and inspect for potential loose connections (ensuring power to them is off.)

Loose wirenut connections (from poorly made wirenut connections) are also a common cause.

At that particular era, you might also want to check that you don't have aluminum branch wring, and if you do, you need to take special care. If the stripped wire ends are silvery rather than pink-to-brown copper colors, you have some extra steps to take.

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  • this was great advice, back online, and now I know how that circuit is laid out. Thanks! Aug 13, 2022 at 22:39
  • @BrianHadley did you get it? Aug 25, 2022 at 13:56
  • @htmlcoderexe yep, one of the fixtures was bad and when I removed it the issue resolved. Didnt bother tearing the fixture down to see what was causing the short though. Aug 26, 2022 at 18:41

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