GFCI trips on a separate circuit

If they are truly on separate circuits then what you describe is happening should not be possible. Perhaps the circuits have a common (improperly terminated) neutral wire and the devices are floating and are seeing transients during start up?

Bob

The microwave oven should be operated on its own circuit breaker from the panel. It is best to use a standard type circuit breaker for a microwave oven, because of its characteristics.

Jerry G.

snipped-for-privacy@minetfiber.com wrote in news:a41ae838-f7c8-4853-9da2- snipped-for-privacy@w1g2000prd.googlegroups.com:

A GFCI trips when it senses that the current on the hot and return lines are not the same [implying leakage to earth somewhere] or when there is a significant voltage sensed on the safety ground.

Look for any way that currents flowing in the microwave's power circuit could be getting to the GFCI for your computers.

Probably unrelated to your GFCI problem.

Sounds like your microwave is the culprit and ready to die. GFCI circuits must be fairly sensitive to sense small inbalances in current in their respective circuit. If the microwave is injecting significant EMI back into your house circuit, no telling what could happen. You could test this theory if you have some sort of emi filter you could plug the microwave into between the outlet and oven. I don't know if a surge protector power strip provides any sort of emi filtering or if it just protects against over voltage spikes.

You could borrow a neighbors microwave for an hour and put it on the circuit where your microwave trips the GFI. If both microwaves trip the GFI, you have a problem unrelated to the microwave and probably some sort of leakage on the other circuit that makes it more sensitive to the minor surges that the microwave causes when it switches.

I have a little mini-tesla coil for checking out high vaccuum stuff. It generates a huge amount of EMI. It will set off any GFCI that is on it's circuit, even though the device is 2-wire. Naturally the spark goes to ground, and would trip a GFCI. Perhaps your microwave has a high voltage breakdown and that's what is causing the circuit to trip. Does it do this more on humid days?

-Paul

Because important details are missing, then different answers are provided; all correct because each is based upon different assumptions.

Bob Shuman's and bz's answers assume a GFCI in the breaker box. As correctly noted, a GFCI's white neutral wire must remains electrically separated from all other neutral wires. And both black (hot) and white (neutral) wires must be keep separate from other circuits so that even milliamps cannot leak through a partially penetrated wire insulation.

If GFCI is in the kitchen, then dodger741's answer is relevant. That assumes the computer is somehow on the same circuit. Not clear from your post which circuit has the GFCI.

Paul's questions about environment when tripping occurs is also relevant.

And f> Sometimes my microwave trips the other circuit that has our computers

It might be worth taking the microwave and trying it on a circuit WITH a GFCI (preferably, both the computer circuit and another one). It should not trip.

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