Engine Block Heater

[jwstewar]

My '99 Silverado w/ 5.3 liter gas has an engine block heater. It was supposed to be around 0 (that is cold around here) so I decided to use the block heater. Didn't notice it when I had used this in the past, but whenever I plug it in to the outlet on my outside electric pole it kicks the GFI. I know (or at least think) the GFI is good because I used it at Christmas for lights. I moved the cord over to the outlet in the shed that isn't GFI and it seems to be working and it hasn't kicked the breaker. Is this common for block heaters to kick a GFI outlet?

[egon]

I'd check the cords and clean the plug in contacts. It should not kick out the ground fault protecter.

Egon

[Justaplain]

My block heater will kick out a GFI. bcs

[beenthere]

I would suspect there is something wrong with the block heater if it kicks out the GFI. Maybe not much, but enough of an imbalance (indicating a short to ground) between the neutral and hot line that the Ground Fault Interupter says "No", something is wrong". That doesn't mean that it will blow a circuit breaker, it just means not enough load is being shorted to ground to blow the breaker.
What this problem may mean is that you could get a "tickle" (small or BIG) if you become the connection between a better ground and the vehicle that the block heater is plugged into, and the GFI is your lifeline.
[img]/forums/images/icons/ooo.gif[/img] [img]/forums/images/icons/shocked.gif[/img]

[wingnut]

I would suggest that you check on the rating of that GFI circuit and on the other circuit. GFI's are not at all tolerant of excess draw ... while most circuit breakers are pretty forgiving ... which is why GFI's are around!
Block heaters draw a fair current ... I vaguely remember the last one I installed was 1500W ... so it just may be that draw is too much for the GFI to ignore.

[beenthere]

Your comments puzzle me, and don't fit with my experience and knowledge of a GFI. If there is no imbalance between the neutral and hot wires from a load, then the GFI should continue to function regardless of the load. The GFI should take more clean load than a circuit breaker will take. I.E. a GFI does not take the place of a circuit breaker. But that isn't how you described it. [img]/forums/images/icons/confused.gif[/img]

I will yield to anyone who can straighten me out as to why a GFI is less forgiving than a circuit breaker, given that both GFI and breaker are correctly installed and rated for the load.

[Argee]

I can add this. Installed some outlets in a GFCI circuit once and when I hooked the power back up it kept popping the ground fault. I traced it down to one of the neutrals making contact with a ground wire in one of the boxes.....Moved them apart and I was back in business....Now for the part I have never figured out.....in the panel, the neutrals and the grounds went on the same bar!! Now answer this, why was it popping the ground fault when they were touching in the box? [img]/forums/images/icons/confused.gif[/img] [img]/forums/images/icons/confused.gif[/img]

[beenthere]

I suspect the box where you found the ground and the neutral touching was on the "load" side of the GFI. That would do it. If they were found touching on the "line" side of the GFI, I can't imagine how it could happen.

The GFI only senses the "load" side for any imballance between the neutral and the hot. That is why you can touch the hot on the load side, and trip the GFI. Don't try that on the "line" side. [img]/forums/images/icons/grin.gif[/img]

[crawdad]

i would suspect that you have another appliance or load on the same circuit.
when the truck is plugged in w/the other load on that circuit it trips it.
this happens to me all the time when i am plugged into my 15A GFI and the compressor kicks in.
or i plug the battery charger in,it trips the breaker.
nothing wrong with anything, except too much of a load.
the breakers doing its job.
in your case it may be different......but see what else is on that circuit.
or put in a new GFI they do go south occasionally.
i plug my gas and my diesel in every night when its below 40 deg.
yea,everyone says why? i say why not.costs next to nothing a day.
truck starts nice and easy,instant heat,less wear,some friends are proud that they never "have to"
plug their trucks in and i get my b***s broken all the time. so what
good luck and stay warm
scott

[wingnut]

although I work with electrical components on a "spare part" basis all the time ... I won't pretend to be an electrical "expert" .... my suggestion was based on my experiences - to-date - with GFI circuits in hazardous locations (pool, etc). GFI's are built to much more exacting specs than standard breakers and will react faster (and be less forgiving) than a regular breaker. Sort of like a fuse vs. a fast-blo fuse.
Having grown up with block heaters ... I'm more than a little familiar with resetting breakers. At work in Alberta, we had constant problems with the breakers for the parking lot circuits ... since too many people added an in-car heater so they could start up and drive away ... and regular circuits wouldn't handle the load of block and in-car.

YMMV