Puzzling Electrical problem

[Shagreobe]

OK, At work (I'm a maintenance mechanic/technician), we have a 120v (USA) twist-lock receptacle that is 1. split into 2 separate circuits, and 2. Showing 120v between hot to neutral, and 12-v hot to Ground.0v N-G, so far so good. The motor that plugs into it does not work, but works elsewhere. There is not much of a circuit, just a breaker, on/off switch, fuse, outlet, and wiring ran maybe 10 feet or so.
And yes, I used my fluke clamp-on to check everything. Can someone explain why I have voltage but nothing runs when plugged in???

[petehall347]

neutral is at ground potential so would see 120v v ground to live not 12v
like yours .
anyway are you checking voltage with motor plugged in ?

[redwire]

It could be "ghost voltage"- whereby you read a good voltage but it's a lie. This happens with digital multimeters.
It's caused by a bad connection that is corroded or wet. That looks good to the multimeter because it has high input impedance and does not draw appreciable current through the connection.

I'd expect 120VAC L-N and L-GND, and a volt or so N-GND. I think OP 12V means 120V? The cord can be checked with some other load, like a light.

You need the "LowZ" feature on a multimeter, this draws more current when taking voltage readings so they're not affected by dirt and water.
Does your model of Fluke have this feature? It's essential for electricians and plant work.

I got screwed over by this fixing a CNC machine,voltage readings at the fuseholders looked fine but the machine was dead, no power. Turns out, CNC coolant residue was everywhere and that was enough leakage current for my DMM to read OK.
Old analog voltmeter showed it right away, no voltage after the fuses- the fuseholder springs had been squished and not making a connection. Cost me many hours.

[Shagreobe]

That should be 120v, missed a zero. We have put a plug with bare accessible wires/terminals in and measured

[stj]

read the voltage again - with the load connected.
incase there is a loose connection upstream.

[CapLeaker]

Only because your meter sez it sees 120vac there at the plug, doesn't mean it can handle current! Plug in a light something halogen or incandescent that draws some current, even if your Fluke has the Low -Z function. Then measure the voltage across that light bulb.

[Shagreobe]

Found a loose neutral wire on the light part of the switch, that I guess was only making contact when I looked at it lol

[CapLeaker]

Just as figured… just glad you found and corrected the problem.

[sam_sam_sam]

Only because your meter sez it sees 120vac there at the plug, doesn't mean it can handle current! Plug in a light something halogen or incandescent that draws some current, even if your Fluke has the Low -Z function. Then measure the voltage across that light bulb.

I would second this idea as well

A loose neutral wire will give you headaches as well

Incandescent light do not lie if the filament is good when I am in doubt that is what I use if I get weird reading on a meter

You got to be careful when checking 24 volt control circuits with a incandescent light because if these circuits have a high current demand on them you will get a false positive that you might have a short circuit but in reality it just pulling more current than the glow of the light is misleading

Because this machine has all of the proximity switches all in the same 6 amp circuit plus a push button switch which is the wire that was pinched to the cover for the switch

I had this situation today on a folding machine it turned out to be a wire to a switch that got pinched in the switch cover and tripping a 6 amp breaker that is reset-able

I was able to get the machine back up and running again with out the switch wiring I will have to fix that tomorrow morning when I get there unless somebody else gets to it before I do

[CapLeaker]

I would second this idea as well

A loose neutral wire will give you headaches as well

Incandescent light do not lie if the filament is good when I am in doubt that is what I use if I get weird reading on a meter

You got to be careful when checking 24 volt control circuits with a incandescent light because if these circuits have a high current demand on them you will get a false positive that you might have a short circuit but in reality it just pulling more current than the glow of the light is misleading

Because this machine has all of the proximity switches all in the same 6 amp circuit plus a push button switch which is the wire that was pinched to the cover for the switch

I had this situation today on a folding machine it turned out to be a wire to a switch that got pinched in the switch cover and tripping a 6 amp breaker that is reset-able

I was able to get the machine back up and running again with out the switch wiring I will have to fix that tomorrow morning when I get there unless somebody else gets to it before I do

Nice find, Sam! I am using the light bulb as a load or limiter quite a bit. Works good. I had a non existing neutral situation at my son's residence. Luckily I checked it before he used it.