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Block heater tripping GFCI

16K views 31 replies 13 participants last post by  ktmrfs 
#1 ·
I had the truck plugged in all night last night for the first time this year. I came out in the morning and it had tripped the GFCI on the outlet. Any one else had this problem? Any good fix?
 
#3 ·
happened to me....the way I had the cord ran allowed it to rub through in one spot and ground out on the metal causing it to trip my breaker
 
#4 ·
i had the same problem with my 05 but never got it fixed before trading it. could be as simple as getting a new cord. my fear was needing a new element as it looks like a PITA to replace
 
#5 ·
i just cut the end off an extension cord and used that, works good now and the cord is longer
 
#7 ·
I inspected the cord carefully, I can't see any place where it would have shorted. Is there a way to test it with a multi-meter?

I tried a different outlet, it tripped too. I tried plugging the cord into my miter saw to see if it was the cord. It worked fine. I really hope I don't have to replace the element, that looks like a PITA to get to.
 
#8 ·
Probably the element has failed internally if it's repeatable across multiple receptacles. Hate to be the bearer of bad news.
 
#9 ·
my cord looked fine too. but like someone said above try cutting the end off and replace it with another end
 
#10 ·
Yes, I would absolutely positive try a new cord before rushing to replace the element. I should have mentioned that. ;)
 
#11 · (Edited)
The cord unthreads from the heater element, so as to allow you to remove the cord and inspect or replace it.
 
#12 ·
Ohm out the element with a multimeter, sound like it goes to ground (direct short)
 
#13 ·
I ohm'd it. It stays open :rolleyes: I'll pull the cord off this weekend to isolate that, but I think I see a block heater replacement in my near future.
 
#14 ·
If it were "open", it wouldn't trip anything.
 
#15 ·
Open as in 100% resistance (multi meter reads 1.0). Is that the right terminology?
 
#16 ·
1.0 Ohms is essentially a dead short, BUT, ironically, that's what a heater element is (essentially a dead short). The 1.0 Ohm sounds normal to me.

GFCI's trip when there is leakage to the ground wire. Taking that same multimeter, measure resistance from the blade to the round ground pin. Repeat for the other blade to the round pin. Both should be OPEN to ground, ie....infinity (same as if you didn't connect the test leads at all).
 
#17 · (Edited)
Heymccall, DP needs to pay you a salary :D

I ohm'd the cord like you said, both blades to ground showed infinity. Now I'm puzzled :confused:
 
#21 · (Edited)
Heymccall, DP needs to pay you a salary :D

I ohm'd the cord like you said, both blades to ground showed infinity. Now I'm puzzled :confused:
Is that measurement with the cord still connected to the block heater element? GFCI will trip with something near 40Kohm or less resistance from hot to ground or neutral to ground. Depending on your meter range selection, "Infinity" could be anthing from 10's of ohms to megohms. If the meter is autoranging you should be ok. If it has manual ranges set it to a 100Kohm or so range and see what the reading is between hot and ground and neutral and ground. It should be over 100Kohms.

Also, is the GFCI an outlet or a breaker in the panel?? If it is an GFCI outlet, it is tripping because it sees a difference in hot and neutral current or a neutral to ground short. If it is a GFCI breaker in the panel it could be tripping because of overcurrent as well. They are a circuit breaker and GFCI. A outlet GFCI is NOT an overcurrent circuit breaker, just a GFCI.
 
#18 ·
In my experience, GFI's don't handle load well. When I was doing construction, we could not plug an air compressor into a GFI. I would try an another receptacle first and see if it handles it better. I don't plug in any of my block heaters to a GFI, just a regular 15 amp breakered outlet
 
#19 ·
I'm starting to think this may be my issue. This is the first time I have plugged in at my current home. Problem is, all my exterior outlets are GFCI. One is direct and the other is tied into the garage GFCI outlet. Would it be safe to replace the garage GFCI with a standard outlet?
 
#20 ·
i tried another outlet with mine and it still didnt work.
 
#22 ·
It's just a regular GFCI outlet, not in the fuse panel.
 
#28 ·
I just offered info on what I have found with GFI's & block heaters, do, or do not replace with regular outlet, could careless. Usually I am not standing in a puddle of water when I plug something in, especially a block heater, cause if there is water on the ground, it's not cold enough to warrant plugging in;)
 
#29 ·
I found the cord and element on eBay for $6.45 or something, spicing in an extension cord is just asking for a problem if an element is bad in a water heater it will trip like your gfci is. For under $7 it seems worth the try.
 
#30 ·
I tried replacing the GFCI outlet, I figured it was a cheap test. The block heater seems to be working. The temperature of the actual external block heater surface (measured with an infared temp gun) went from 122 to 183 in a matter of 15 seconds. That means it must be working. It is causing a fair amount of noise though. Is that normal? I don't recall hearing the noise before. Here is a video of it. You may need to crank your speakers. This is with the block heater plugged in and the truck off.



I think I will just replace it, just to be safe. I couldn't find it for $6 but I did find a heater with cord for about $60. The real PITA is actually replacing it, but I'll have the coolant drained this weekend to pull the water pump out, so i might as well do it.
 
#31 ·
yea i dont think its suppose to sound like that. plus thats one reason i didnt mess with mine because of draining the coolant but if you have it drained already i would change it too.
 
#32 ·
mine makes noise. As have all the vehicles I've had with block heaters or tank heaters. never caused any problems. I suspect it is tiny water bubbles bubbling off the surface of the element. Element likely gets above boiling point of the coolant. When the block is cold you don't have any pressure in the radiator and coolant boiling point is about 240F IIRC with 50/50 antifreeze mix. It relies on convection to for the heated water to move through the block. Once the water temp in the block gets above a certain point the element will turn off by itself. FWIW, the electric element in my trailer water heater also makes a similar noise. You can hear mine from 10' away or so.
 
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