Electrical mystery

[Peter B.]

I recently experienced an electrical phenomenon that I can't explain.

1. The circuit is a 20 amp branch using #12 conductor that feeds a GFCI duplex outlet that is used primarily for a washing machine. There are no other outlets on this branch.
2. The home is new and all wiring is to code.
3. When tested with a Ideal Suretest (tm) circuit analyzer, all measurements are normal.
4. When the washer is the only connected appliance it works with no problems. 5. When my 1.5 HP Porter Cable compressor is connected to the circuit with no other appliance, it works flawlessly.
5. To date, I have only tried this with the washer and the compressor.
6. In neither case does the GFCI trip.
7. In neither case does the breaker trip.

The Problem: Whenever the compressor and the washer are both plugged in to the outlet at the same time, neither will run.

With the washer turned off, but plugged in the compressor will not start. With the compressor plugged in, but not running, the washer will not start.

This is not a situation where the compressor is drawing too much current to keep the washer from starting. Nor is it a situation where the washer is drawing too much current for the compressor to start. In both cases, the other appliance is not running.

There appears to be some interaction between the washer and the compressor that I cannot explain.

I am baffled.

Pete

[Wade Lippman]

You say they will not run if the other is simply plugged in, but you don't say why. Does it trip the GFCI, or does it simply not have voltage, or what? Does it matter which receptacle either device is plugged in? (odds are it is a bad outlet, but more details would be helpful. BTW, code requires it to be a 20a outlet.)

[Peter B.]

I don't know why. Neither the clothes washer nor the compressor will start up when the other is plugged in.

I stated in my ordinal post that it does not trip the GFCI. The voltage drop on the outlet is 3% at 20 amps (using an Ideal Sure Test tester).

The outlet tested perfectly. I doubt that it is a bad outlet. It is a

20 amp outlet on #12 conductor with a 20 amp breaker. All components are new.

It does not appear to matter the order that the washer and compressor are plugged into the GFCI outlet.

Remember, this is occurring when the other appliance is not running. It is definitely not a case of an overloaded circuit.

Pete

[Speedy Jim]

I would suspect some mechanical failure inside the recept itself. For some reason, inserting both plugs stresses the device enough to break the circuit. Try another recept.

BTW, GFCI recepts are *not* required for a dedicated laundry circuit.

Jim

[George E. Cawthon]

No matter how it tests, something is wrong with the outlet. Unless something is wired terrribly wrong, I would bet that when both plugs are in, something moves inside the outlet so that no contact is made with one of the wires.

Just install a new outlet. You do know that components sometimes have manufacturing errors, don't you?. Or the installer broke something while installing the outlet. Don't look for something complex.

"Peter B." wrote:

[Peter B.]

We are indeed going to do some additional testing. In my over 20 years as a builder, I have never seen anything like it. I'm going to switch out the receptacle on Monday. I'll let you know if it solves the problem.

I know that GFCI's are not required for the dedicated laundry circuit. But we like to keep our clients as safe as possible and it has never caused a problem with washing machines.

Pete

[Peter B.]

I understand that electrical components can have defects. A couple of years ago I was having a high failure rate on three-way switches. Out of eighty homes in one project, my electrician replaced at least one three-way switch in 50% of the homes within the first year.

I am used to component failures, but this one is so bizarre that I have never seen this type of problem before.

Nothing is wired incorrectly. It test perfectly. Being a GFCI, it would not tolerate a significant problem without tripping. I'll have the device replaced Monday and I'll let you know if that solves the problem.

Pete

[Tony Hwang]

[Peter B.]

We tested the circuit and it turned out to be a defect in the GFCI device. A new GFCI outlet corrected the problem.

I have never seen a GFCI behave in this fashion. Whatever the problem was internally, the device still tripped when presented with a fault.

Thanks for everyones input.

Pete