When I plug my engine heater in, it pops my GFCI in the garage. I presume this is just a short somewhere in the heater, but just looking to see if there is an angle I haven't considered?

Thanks for any input,

Mike

 

Try it in another outlet(non gfi) it may be just too much of a draw for a gfi outlet.

 

If it continues after changing the outlet, check the entire wiring to the heating element. It may have become chaffed somewhere. I was able to change just the wire after finding out I had a pet mouse that ate the wire. If you have to change the element, be sure to drain the radiator and you can probably drain the block by removing one plug from the block before removing the element.

 

GFCI outlets do not work well for block heaters. It does not have to be a short to trip them. All that has to happen is the heating element is touching the block which will cause electrical leakage.

The extension cord must be at least 12 AWG wire for a 50' extension cord and in excellent shape. If it is over 50 feet I would recommend a 10 AWG cord.

The outlet looks at exactly how much electric is going out the hot wire, if exactly the same amount is not coming back on the neutral wire the interupter trips the circuit. This imbalance could be so small it would not light a 1/2 watt bulb, but it will trip the outlet.

If the neutral circuit and the ground circuit touch each other the outlet trips.

The inductance loss from the cord laying in the snow/ice/rain/puddle will cause it to trip.

 

I have had a similar problem with my block-heater and GFCI. Dave S. has described the GCFI circuit quite well, it works just as he has describes.

This is what I found with mine, and have had no problems since:

After several blown GFCI's and cold starts I decided to get my trusty (good quality) ohm-meter out and check my heater circuit for continuity to ground. This is an easy process, anchor one meter lead to the center ground terminal of the block-heater plug and the other lead to one one of the remaining, and then the other. If you read some resistance (even over 1,000 ohms) you have a problem. Some of the electrons are finding thier way from the hot lead to the ground terminal. What that means is that they are not returning to the plug on the neutral leg. What's going out on line, is not comming back on neutral, and the GFCI blows. I found several thousand Ohms to ground. I then isolated the heater and found no measurable resistance to ground (good heater). It was the cord! Not just the cord, road-Goo on the cord. The de-icer used in this part of the country conducts electricity. Even my tires were giving me measurable resistance.

The solution: I now take my undershirt and wipe the Goo off the plug end each night before I plug in. No more problems...........

 

Master electrician here