block heater trips house GFI

try a hairdryer? maybe there is some moisture somewhere.

 

Does the GFI pop immediately or after the heater gets hot?

 

Your heater element or cord is shorting or burned out. Check the plug, cord and terminals first for wear, security and corrosion. Contact cleaner is your friend. Removing the element/cord assy will make inspection easier if no obvious damage is found. Wiring can be repaired. Ring the wiring and element seperatly. If all looks good, go to dealer parts counter and ask to ring out a new one off the shelf to verify. If they do not have one, ask someone in service if they will print out the resistance checks for you off the manual. Please and thank you sometimes still works. If not, someone here might give you their resistance readings for a comparison.

 

Hi
I measured the resistance of my EBH and it was ~ 35 ohms.

 

"I've tried different outlets on different circuits as well as different extension cords...all with the same result."



Your drawing more amps than your GFI limits while plugged in. My recommendations stand. It is a dedicated system. Worst case it's only $59 and a little time to fix. Best wishes.

 

Brian:

While you had the ohm meter out did you check the resistance in the cord? Likely you will find that it is bad / shorted. A few of us have found the problem at the 3 prong end due to wear of plugging and unplugging it in an extension cord. With that, of course, you can just cut plug off and replace it. For most of us, unfortunately, the problem is at the connector to the heating element and for that, you just have to replace the entire thing.

Bob

 

I'd pull the heater out of the car and check the chord, if it isn't the three prong plug shorting it could be that the wire was rubbing somewhere and shorted, lots of motion where electricity is concerned, lots of motion where cars are concerned.

 

It is my understanding that GFIs can get more touchy as they age and as they see more use. You might consider changing the GFI itself.

 

If resistance across block heater prongs is (normal) 35 ohms: maybe a problem with your extension cord.

 

i have replaced a few for this reason.

 

In that case you have a short between the neutral and ground wires. The purpose of a GFI is to detect this very situation. Try replacing the plug first.

 

No, he has an open between neutral (i.e. one of the prongs) and ground.

I do hope he used a digital meter, or adjusted the range of his analog meter, to verify that 'open' exceeded something like 100kohms. On an analog meter without a range change, leakage strong enough to trip the GFCI could still register as 'open'.

 

Since the OP tested the GFI and extension cord with other devices that require substantial power, my guess is that the power cord to the block heater has an intermittent problem which did not manifest itself during the ohmmeter testing.

 

No, I beg to differ. The neutral and safety ground should be isolated (i.e. open) at the load. The entire purpose of a GFI is to detect an imbalance of current between the hot and neutral wires. The fact that he sees the same resistance between the hot terminal and the neutral and ground proves that there is a short.

 

Are we reading the same OP?

I read it as:
35 ohms hot to neutral (prongs);
Open hot (prong) to ground;
Open neutral (other prong) to ground;
Short ground to chassis.

 

My apologies - I clearly misread the original post.

Peace on Earth and happy holidays.