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the power outlet where my tv was plugged in lost power all of a sudden. However, when I plug in a receptacle tester, the power goes back on but when I remove the receptacle tester, power goes off again. What seems to be the problem.


I already checked the duplex receptacle and the wires are secured firmly with screws and not poked into the hole. I also tried plugging an extension into the outlet and plugged the receptacle tester into the extension and it also worked. But nothing works without the tester.

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Are you trying to say that in a duplex receptacle, you get no power on one outlet, however, when you plug a tester into the 2nd outlet, the first outlet gets power again? –  Aaron Oct 8 '12 at 20:27
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3 Answers

I suspect that your outlet has a bad contact, so that (let's hypothesize) one of the prongs does not work. Let's further hypothesize that it's the neutral that has the bad contact.

Also, let us assume that the two neutrals in the outlet are connected to each other. Just not to the power grid.

Suppose that the tester creates a bridge between neutral and ground. The resistance of this bridge is not anywhere near zero ohms, but that might not matter.

What that means is that the neutral receptacles in the socket now have a path to ground, and even if that path is resistive, that completes the circuit. Current can flow from hot, through the device, into the neutral prong (which has no grid connection, but does have a connection to the tester's netural) and then, via the tester, to its ground prong. If the device has a small current draw, then its effective resistance may be significantly greater than the resistance in the tester, and so the tester's resistance might not matter much. The device may see a voltage drop, but its power supply may be tolerant to it.

Anyway, needless to say, replace the outlet.

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Something's worn or broken in the contact system inside the receptacle. Replace it before something touches something it shouldn't. Or heats up because of bad contact and melts stuff.

The insides of these receptacles are made up of strips of brass which is work hardened to have spring. If the contact with the plug is slightly loose, the brass can heat and lose its springyness (annealed).

Pushing something into the opposite plug hole can put pressure on the brass contact strip and cause it to make contact in the loose socket. Sounds like your symptom?

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That's quite plausible. –  Chris Cudmore Oct 10 '12 at 0:41
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How exactly do you know that the power is going back on?

If the TV is still plugged into one recepticle and simply plugging the AC tester causes the TV to come back on ---- then you need to immediately investigate repairing and replacing the duplex recepticle. It is likely that the wiring in the box is using the quick connect type connection where the wires poke into a hole in the back of the outlet. One wire must be loose and making an intermittent connection. This could be caused by a wire that is improperly installed or the internal string contact that is supposed to retain the wire is broken. Simply installing the AC tester into the other outlet is apparently moving the contact metal work inside the recepticle just enough to cause it to touch the loose wire.

Do note that a loose wire like this is unsafe and could lead to a fire - so please investigate immediately - for the sake of yourself, your family and your dwelling.

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+1 for replacing the receptacle and the warnings that this is unsafe and could lead to a fire. –  BMitch Oct 9 '12 at 13:49
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+1 not to mention receptacles are just too inexpensive to risk. –  Matthew Oct 9 '12 at 14:45
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