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Electrical question

Just1more

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i tried to use my 120v air compressor today and it would not start up. Grabbed the multi-meter and the outlet is only showing 117v (lead wire to the shop shows 120v). What would cause a drop?
 
That fluctuation can be normal. Line voltage varies 110-125'ish, depending on other loads (e.g., your AC or lights running). On a hot day when everyone's AC is running, it can drop substantially and be a brown out, causing problems for electronics and motors.

I had one the other day measure 50V. That ain't normal. Replaced the outlet, which was apparently bleeding about 70V to ground without overheating or arcing (yet).
 
3V shouldn't affect the compressor. Sounds like something else is going on. Check between hot and common, hot to ground, and common to ground. I'm sure one of the resident ODT electricians will be along soon to give better advice.
 
Bad outlet, loose taps, bad breaker.

You have something in the circuit that will not handle a high amperage load. Plug your meter into the line with the compressor and try to turn it on. Bet the voltage drops way down.
 
There is something else. 117VAC is fine. Hot to ground should measure the same as hot to neutral. Neutral to ground should show nothing as ground doesn't carry current. Typical house range is 118-123 VAC. If it starts in other outlets the start cap or breaker is OK. I would look at the plug, it may have a loose connection and just happens to start the way it is twisted.
 
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