Shocked while Barefoot on Concrete Floor

[grmaculsay]

The past two mornings I received a shock (not static) while standing on a bare concrete kitchen floor, and touching the metal back of the counter microwave. I've unplugged the microwave and set it aside for now.

I realize that the microwave body may have become energized due to an internal wiring problem, but could this happen under the right circumstances for some other reason?

Likely my feet were damp at the time too. My bad.

Outlet is grounded, three prong, tests okay.

We recently had all flooring removed down to the concrete, and we had two panels consolidated into one (new ground rods, etc).

I do plan to call our electrician.

Thanks for any additional advice or concerns based on this limited information!

[John Nelson]

How did you determine that the shock was not static? If you touch it repeatedly without moving, do you get a repeated shock?

You may need an appliance repairman (or a new appliance) rather than an electrician. Try plugging the microwave into other outlets on other circuits in other parts of the house.

[ibpooks]

Were you also touching an electric stove? Sometimes older three-wire circuits to stoves can cause this problem. Calling the electrician is a good idea -- there shouldn't be any stray current on the metal frames of appliances. Perhaps something was overlooked with the recent panel upgrades?

[grmaculsay]

Received that tingly, oscillating nipping - this wasn't as bad as the other few times I've been shocked in the past.

There is a three-wire electric stove within a foot of where I was standing.

I'm not willing to play around with other plugs or circuits, just to possibly receive another shock.

Thanks for the replies, folks!

[ray2047]

Good idea to call an electrician but if you have a multimeter you could do some tests while wearing shoes. Touch one probe to exposed metal on the microwave and one probe to stove. Then check each to a good ground. Wear rubber soled shoes and don't touch any bare metal. Shoes may not protect so don't touch is your real protection.

My guess would be a loose or disconnected neutral on a three wired stove. If your tests show it is the stove turn off the breaker till the problem can be fixed.

[grmaculsay]

No voltage between the steel back of the micro and the stove. Wore shoes this time

It's pretty disconcerting... with shoes on, I can pretty much handle the microwave without a shock. I'm not taking the shoes off again, though.

[Bud9051]

The times you got shocked, were there any other appliances, stove, dryer, or other, that were running. Sometimes the voltage you felt is only there when something is running.
Bud

[Gunguy45]

Well, just in case this stimulates someones brain.

Same issue for a while (couple of weekends) when I cleaned the dust and nicotine stuff off my garage TV screen. TV off btw. First time it happened I checked the outlet with a plug-in tester, and then cut the power and checked with a meter. Everything good. No bad lights on the tester and no voltage between neutral and ground. No voltage between the screen and ground (ok, so what was I feeling?)

Couple of weeks later (ok, maybe months) no tingles at all.

I"m not worried about it...just thought I'd throw it out.

[grmaculsay]

Bud, the coffee maker was running, plugged into the same circuit as the microwave (not for long, it's already on the most over-committed circuit in the house). Micro was off.

We had an overflow situation with the coffee maker (where someone, yours truly, forgets to put the carafe back in the holster)... that was yesterday, and that was the first day I was jolted. Both times I was shocked I was in contact with the microwave chassis in some way, with my hand really close to the coffee maker.

Crap, who knows...

Time for a new microwave circuit over the range, new micro, maybe run over the coffee maker, etc. It sure would be nice to know what the cause of this is, though.

[Bill190]

This could be the microwave, however if your electrical grounding system is ok, then you should not have been shocked!

Also all grounds in a house interconnect. So something else *anywhere* could be placing a voltage on the ground.

There could be a faulty appliance *anywhere* and a loose or poor ground connection, then the voltage comes up through the 3rd prong on the microwave outlet and connects to the microwave metal cabinet.

Anyway good thing to call electrician and track this down.

[Bud9051]

A question about your coffee maker overflow been there, done that, but I have had occasion to take some of those things apart, and you would be shocked (pun intended) to see how crude they are inside. If it is/was still wet inside from the coffee getting down inside the base, you could have/had some leakage to ground from the hot inside. Can't guess the path, but worth checking. The timing is right as well. The microwave might be providing just the ground, and the voltage you are feeling is coming from some of that excess coffee/water in contact with a wire somewhere.
Bud

[grmaculsay]

Okay, decided to do the wrong thing and try and recreate the shock.

Plugged microwave in, bare feet on concrete floor, not touching anything else. Zapped when touching a sheet metal screw holding the case together on the back of the microwave. Did it twice, made me hop around and swear.

Put shoes on, no shock when touching the screw.

Removed microwave from counter.

[Bud9051]

ROFL Did someone get pictures Anyway, now that you know it is there, try to get it on your meter. Keep your shoes on.
Or the better question, are you ready for an electrician?
Bud

[grmaculsay]

When reading that response, I thought it said "am I ready for an electrocution?"...

Definitely going to call the electrician, but going into the weekend, it will probably happen next week. I can kill the circuit at the breaker box, as there isn't anything else on it that's critical.

When touching the probe of my meter on any of the screws on the back of the plugged in micro, I see 12-15 volts...

[grmaculsay]

One more thing. I plugged the micro into a known good circuit (the washer plug which only services the washer and installed last year). No voltage at the screws on the microwave.

Lastly, I plugged the micro into the only other outlet on the original circuit where I had the shocks... a GFCI, by the way, which used to service the fridge, and the micro showed 8-10 volts at the screws.

[Bud9051]

When you read that voltage on the screws of the microwave, where is the other probe touching?
Bud

[grmaculsay]

Man, I must have been touching a bad ground... multimeter reads 118 volts when touching the microwave housing screws and a GOOD ground, such as the dishwasher door hinge or stove hinge.

Thanks again for responding - this forum is quite responsive!

[dzdave00]

You should turn off the circujit breaker for this circuit right now and probably call an electrician. This can kill someone.

You have a ground fault on that circuit and it is not being cleared by the breaker. Either the breaker is defective or the ground is open somewhere on the circuit.

If you want to troubleshoot this, do you have a 3 prong plug in tester that you can plug into the microwave outlet? It is also troubling that the GFCI outlet did not trip. Is the GFCI downstream of the microwave outlet?