The block heater on my 2005 LLY trips ground fault circuit interrupter outlets when plugged into them, but does not trip the circuit breaker on a conventional outlet. I measured the resistance at about 500,000 ohms from both hot to ground and neutral to ground. Anyone else have this problem?

Thanks,
John

I think your GFCI simply can't handle the load. Use a non-GFCI outlet.

Very small amp draw on those gfci's, use non- gfci

Mine does it too,

For some time, I was thinking the block heater wasn't working, it never seemed to warm up.

Glad to hear its not just mine, but I wonder why. I regularly run a 1500 watt fan heater in my camper on the same GFCI outlet, and that doesn't kick it.

It is hooked to a thermostat, so it comes on whenever it gets cold in there. That is about 13 amps at 115 volts.

There must be some other reason.

how old is the outlet? could be going bad....oversensitive.

I don't plug my truck up, but my CAT end loader at work is plugged up in a gfci and never trips it.

my block heater is also plugged into a gfci outlet- no problems here.

Same here, I plug mine in at work during the day and it is a GFCI Outlet. I have clamped an amprobe on while it was running and it only pulls anout 7.5 A I would guess you have something wrong if the GFCI is tripping.

A GFCI Senses voltage return on the neultral side of the load and if there is an imbalance detected it will trip the GFI most of them are set at 3-5 mA to trip.

How 'bout a bad extension cord? Maybe try a different one...

I think your GFCI simply can't handle the load. Use a non-GFCI outlet.

The GFI will not trip on an over-current, it's not a circuit breaker.
My defective cord would trip a GFI with 200K ohms Hot or Neutral to Grd.
The GFI is probably working, and your heater cord probably has issues.

Mine did the exact same thing. What I found was a small amount of coolant weeping through the block heater terminals causing the gfi to sense the return imbalance which trips the gfi. Unplug the block heater cord from the block heater and check. Even if it is water from other sources (rain, snow) it could also cause this. I would not continue to use the block heater until you figure out what the problem is. You will eventually burn up the weakest link, whatever that may be. If it is coolant you will need to replace the block heater.

Thanks a lot for all he quick replies, especially those of you that use a gfci with no problem, and to zf6 man for the amp reading - there goes my excuse to go out and buy a clamp-on. Tried two gfci circuits, both are 3 years old; 1500-watt heater does not trip either gfci; extension cord doesn't trip when used with other loads. As soon as I get my dead Land Rover out of the way to get in the garage I'll crawl underneath to look at the connection on the heater, but meanwhile will make an appointment with the dealer since I'm still under 36/36,000. Thanks again!
John