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I have two outlets on a circuit and a sprinkler controller that went dark a couple days ago unexpectedly. Nothing I know of changed in the house that should have affected the circuit.

I checked the breakers and none were blown and I reset them anyway just to be sure. I used a contactless tester to check each outlet, even taking off the plate and checking against the black/hot wire directly.

The outlets are about 20 feet apart. One is outside and therefore on a GFCI. The sprinkler is direct wired behind the GFCI (so not in series) so I know the GFCI was not the cause.

I do not know what else is on this breaker. We had solar installed 5 years ago and they did a shit job relabeling the new breaker box they put in. I know now I need to remap it. My point being is that it’s possible more outlets are on the circuit that were not affected, though I don’t know at the moment.

Anyway, today I went back to the outside outlet as I was going to take it apart and see if I could find anything—literally anything, and noticed before I got a screwdriver on it that all the power was back on. I did nothing.

Does anyone have any idea what could cause this?

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  • i have the same problem, we have installed a large switch for changing from a direct line to the generator. After 5years (is not used) it just malfunction and making my home blackout and turn back on for no reason, is it any switch for your house line? Jan 8, 2021 at 13:49
  • @Cubic273.15 I strongly urge you to ask a new question about giving your setup a safety review, and give us pix and relevant details including model of the panel. Generator interlocks are good, but there are many mistakes which can be made in this area. Jan 9, 2021 at 0:29

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This is a fairly common failure usually seen when backstabs are used. Backstabs are the push in connectors when under heavy load they can open up and sometimes later they reconnect.

This also happens with loose wires in wire nuts and even broken wires. The loose connection heats up moves apart and the circuit is dead , after cooling down or some vibration it reconnects until a load is on the circuit.

If you want to find the source of the failure but a plug in heater or hair dryer on it and turn it on this will usually open the circuit.

Why the circuit is not complete test each receptacle or device until you find the last working one or first non working one in that circuit. The problem will be at one of those 2 places 98% of the time. If you pull the receptacle out and don’t find a problem and turn the power back on and it works if it was back stabbed that is usually the bad one and you need to replace the receptacle or move the wires to the screws.

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  • A friend of mine in the insurance industry says to never use backstabs for precisely that reason (fire hazard), so even if the outlet is working, moving the wires from the stabs to the screws is a good idea.
    – Duston
    Jan 8, 2021 at 15:18
  • I have seen minor fire damage from backstabs but the box “usually” contains the arcs and sparks , the UL calls them “safe” but the NEC requires arc fault breakers on everything now when they were originally to prevent electric blanket fires. In my opinion trying to cover up a bad practice of using backstabs.
    – Ed Beal
    Jan 8, 2021 at 16:08
  • Alright but there's an assumption made here about about backstabs. None of these outlets are using that: Wires are on the screws. The sprinkler system that is wired to power before the GFCI in the same box is properly wired, twisted and wire-nuts.
    – Etherplain
    Jan 8, 2021 at 18:08
  • Here's a thought: the outside outlet is the end of the run, the other is (I'm pretty sure) second to the end of the run. In any case I checked literally every outlet in the house and no other was out. I checked the feed wire with the contactless detector and no power was coming in. If there is a backstab on an outlet earlier in the series, wouldn't it also go dark if it was loose or would it simply not deliver power to the next outlet?
    – Etherplain
    Jan 8, 2021 at 18:14
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    I just re read your last statement and you are using a non contact tester. These don’t check the neutral or return side and can be fooled by phantom voltages. If you have a plug in light or one of those testers that plug in and the neon lights on the back light up that is better and for a couple dollars extra you can get one with a GFCI tester.
    – Ed Beal
    Jan 8, 2021 at 20:14

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