Kitchen circuit suddenly reading 40V

Sounds like you might have a loose neutral somewhere. The cheap push-in backwire terminals are notorious for problems like this, they ought to be banned IMO.

Sounds like you have a second GFI outlet that was feeding this GFI outlet. Look around to see if you can find another tripped GFI outlet. You also might want to pull the panel cover and make sure you're getting full power out of the breaker instead of assuming so based solely on the operation of the handle.

It turns out he had a bad connection at one of the upstream receptacles. There was a burn mark at the connection. Someone should've given the screwdriver another twist originally.

Its best to test outlet voltage with a Wiggy. Wiggys apply a load to the circuit when getting a reading. You wont have to worry about those phantom 40V or so readings from DVMs.

Just plug a lamp into the circuit.

And stop playing with your 'wiggy'.

I just got done playing with DimBulb. Does that count?

I had this problem in my first house and it was a loose neutral in the panelboard. The electrician had placed 6 neutrals into a lug and they were loose. Then one day they decided to burn up approximately 2 inches of wiring.

No, but wash your hands. We have no idea where its been.

Good point. It's been in mommy's hamper again, of course.

At least his green skin won't be out of place on the 17th.

Right. And then measure both the hot and neutral voltages to a known good ground. That will tell you which conductor the fault is in.

Work your way back toward the source (panel) until you pass the fault location.

Reminds me of a time when I had ~40 volts or so on all circuits once.

I awoke to the sound of a (plugin) CO detector, but it didn't sound normal, it was very weak and sick sounding. Flicked on the light, which came on as a very dim red, as did other lights. I figured it was some power fault and I verified it with a meter in an outlet. I think it was actually closer to 48V. I unplugged the refrigerator and the alarm, disabled the heater (motors don't appreciate low voltages) and went back to bed. I never did find out what sort of fault would do that. That was

You've been sitting in that dim light for 20 years? ;-)

Odds are that if you didn't do anything to fix it and it went away on its own, it was a utility problem.

There's certainly worse kinds of utility problems. About the same period of time a high voltage line fell on a lower voltage line feeding my friend's neighborhood, it burned out the power supply for every electronic item in the house and blew the bulbs in all the lights that were on at the time.

Yes that's what I concluded, after a quick check for anything unusual. Seeing the streetlight and all the neighbors' lights out made me think it was a utility issue.

I still wonder what kind of utility issue would cause wall outlets to have 40-48 volts.

Something like that happened near my father's, also around 20 years ago. The top of a pole broke off during a winter storm, and drops to cottages got something like 7200 volts when the MV distribution lines made contact with the secondary drops. Two cottages burned to the ground.

If the one phase you are fed from opens between you and the source (blown fuse), wye-delta transformers along the line will back feed that phase. But due to their high impedance, the voltage can be very low.

I do not understand your answer and need some clarification.

By "wye-delta transformers" do you mean wye primary windings on the utility side and delta on the secondary on the consumer side? Then, if one of the delta windings opens, I can picture operation as an open delta.

I also have difficulty picturing driving the primary wye without a neutral connection to handle unbalanced loads. Without the neutral, the unbalanced load in one of the wye legs will become magnetizing current in at least one other leg. That is not good.

Please explaing further.

Bill