Thread: Polarity changes when light switched on

Here's one for minds smarter than mine. The scenario is: When I plugged my 3pronged tester into the outlets in the detached garage, the tester showed a hot neutral reverse. Then when I turned the wall light switch off, the lights went off (as they should) and the freezer stopped running. However; my tester was still plugged into an outlet, and the lights changed on it to a reading of hot ground reverse. Turn the light switch back on, and the freezer comes back on, the lights come back on, and the tester changes to a hot neutral reverse. Can someone tell me how these outlets have been wired? Obviously, I have deferred to an electrician. Garage was built in 1995. Thanks in advance
Steve

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1) It is likely a 3-way light switch, with another light switch at another entry door. If so, the carrier that provides power to the two locations is hooked up wrong. If not, this is worse than we thought.

2) It is retarded to plug a freezer in to a switched outlet. There is no explanation for why the wall outlet in a normal garage would be switched in the first place. That is for interior rooms that are lacking ceiling fixtures.

3) The 3-light testers get confused when they encounter amateur wiring. The poor little tester can't make sense of it either.

4) The freezer may be encountering the same crossed-up wiring as your tester, but can't run. The chassis could be energized with the reversal, so it is a scary situation there.

Your switch is wired to open the grounded conductor ..white wire) which has then been terminated to the brass screw on the receptacle your tester is plugged into and the black wire to the grounded (neutral) side of the receptacle. Switch on and you get a hot / neutral reverse. When you turn the switch off you open the grounded conductor and your tester then shows hot ground reverse. Which is an open neutral.

A switch simply completes a circuit it doesn't care whether it is opening or closing the black .. hot wire or the grounded conductor aka neutral ...white wire.

Thanks Roger. That is simple and makes sense.
It doesn't explain why he's wired several wall receptacles to the light switch in his garage, but there's no explaining a lot of the stupid stuff we see.

Originally Posted by John Kogel

Thanks Roger. That is simple and makes sense.
It doesn't explain why he's wired several wall receptacles to the light switch in his garage, but there's no explaining a lot of the stupid stuff we see.

I'm really just guessing John ... you may be right in your analysis.. It may be any number of mis-wire possibilities. Maybe he is switching the neutral on a MWBC .....

Originally Posted by John Kogel

Thanks Roger. That is simple and makes sense.
It doesn't explain why he's wired several wall receptacles to the light switch in his garage, but there's no explaining a lot of the stupid stuff we see.

...reminds me of the living room in our previous home. It had built-in cabinetry and entertainment center in the living room; with outlets and speaker wires in there (nice set-up). But there was a hard to see wall switch in one of the bookcase shelvs that controlled all those outlets.
I nearly freaked out when a week after we moved in everything stopped working in there. I nearly called an electrician until I came about the switch (wife turned switch off while trying to figure out what the switch did while she organized her nick-knacks in the shelves).