Block Heater Blowing GFCI...

TBigLug · Dec 26, 2009

Well, my block heater has been working fine. Use it everyday. I went out this morning to plug my truck in before I leave for work and as soon as I plugged it in it popped the GFCI on the plug. The cord is a HEAVY 25' 20 amp contractors cord and it is plugged in to a 20 amp outlet that is on it's own circuit. Any ideas?

TBigLug · Dec 26, 2009

Just went out to start the old girl to let it warm up for the ride to work. No start after 10 seconds of cycling the GP's. Manually cycled them for another 5 or 10 seconds. Acted like it wanted to start but no joy. Let it sit for a minute and unplugged the GP solenoid and gave her a 1/4 sec. snort of go mist and she fired up. I definitely gotta get this block heater thing sorted out. I'm thinking some of the GP's must not be working either since it's only 30 degrees out this morning. I shouldn't even have to plug in until it hits 20 or so.

NJKen · Dec 26, 2009

If its tripping a GFI you probably need a new heater. If the element starts to go bad and current leaks to the antifreeze it then has a ground path. This is not enought to trip the circuit breaker sinnce the is not a direct line to neutral or line to ground short. In other words, the coolant will act as the heater! Not good
Ken

sassyrel · Dec 26, 2009

NJKen said:
If its tripping a GFI you probably need a new heater. If the element starts to go bad and current leaks to the antifreeze it then has a ground path. This is not enought to trip the circuit breaker sinnce the is not a direct line to neutral or line to ground short. In other words, the coolant will act as the heater! Not good
Ken

same thought--or,the cord is rubbed thru on the frame somewhere,grounding it slightly

TBigLug · Dec 26, 2009

sassyrel said:
or,the cord is rubbed thru on the frame somewhere,grounding it slightly

I think this might be the case. When I got back from work just now I pulled the plug out from a differant slot in the grille to try and plug it in again and it worked fine. After a quick bite I'm gonna run back out and give the cord a good looking over. Unplugged of course! LOL

vikurt2002 · Dec 26, 2009

I had the same problem, plug in heater and trip gfci... I put a multimeter on the plug and it showed a short. I unplugged the cord from the heater element and then it showed open. So I replaced the block heater, now it works great. The element that I pulled out looked pretty rough but I still didn't really understand why it showed up as a short.. now it makes more sense. The good thing is NAPA has good replacement block heaters for reasonable price and replacing it is a snap. (Although I had a hard time getting the third bolt out of the starter so I could get at the heater)

ocnorb · Dec 26, 2009

I have a similar issue. At home my block heater works fine... at work it blows the GFCI as soon as I plug it in. My home has a GFCI, but it does not trip when the truck is plugged in unless I get the cord end real wet. Starting to think that some GCFIs are too sensitive for the inductive load of a block heater.

Block Heater Blowing GFCI...

TBigLug

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sassyrel

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TBigLug

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