Block heater - popped GFIC electrical question

Was going to move my combine today before the deep freeze moves in. Went to plug it in, and it pops the GFIC on the line. Does not pop the breaker, but maybe the GFIC gets to it first?

Anyhow, nothing to do but replace the block heater? I thought it worked last year with no issues, same building, but I'm not totally sure I plugged it in.

Not real easy to get to a non-GFIC and don't know much about it, if I can test or see anything obvious wrong with the block heater. I guess a meter between the ground plug and either of the flat pegs would show something? But nothing that would help change thingsanyhow?

Other things are running fine on this circuit, so shouldn't be the GFIC itself maybe?

Paul

Doesn"t take much to pop a GFIC. Meter test would indicate if wires are crossed internally, but why the GFIC out there? Could replace it with regular plug, or is it required for code? I don"t have any in the outbuildings, and some was wired by a real electrician...LOL. You could switch the single box with GFIC to a double box, with a regular plug wired ahead of the GFIC. For a test, run an extension cord from regular plug, to the combine.

My 4-5 year old shed, woulda been wired 4 years ago maybe, it was done to code. Not fancy, got 5 outlets in the building. Only building that has GFIC don't have a one in the house, but it is what it is. First time I've had anything bother with it. Actually I had to go look at the outlets to see if I even had it, checked the breakers and they were fine, took me 3 minutes to realize oh maybe.....

Think that is fairly recent that GFIC is code in storage buildings here.

Paul

What happens if you simply push the reset button? I have a 50 foot 10 gauge extension cord that I use all over the place, but every GFCI I plug it into pops immediately. However, if I leave the cord plugged in and just push the reset it will hold fine.

Is it a 15 or 20 amp GFI?
The 15 amp ones don't seem to last very long and will pop it seems for no reason.
If it's a 15 amp try replacing it with a 20A.
I had to install a GFI to meet code for an outside receptacle on my back deck.
It kept popping all the time.
Got tired of it and just installed a 20A regular outlet.
Done.

Block heaters fail/short/burn/start fires far more often than people like to admit.

Just a few days ago, someone asked me to check the block heater on a semi.

The plug at the heater end and nearly a foot of cord were CHARRED. It's not an ancient truck, either.

Likely, the GFI is doing it's job and protecting you from a failing block heater.

First off, most outdoor receptacles plus concrete floor pole buildings and several other locations require GFCI protection if your jurisdiction had adopted any of the later NEC's BUT THATS JUST A STATEMENT that may or may not hold true or be required in your jurisdiction, I'm ONLY saying, do as you please, this is intended as engineering information only, NOT to start a code discussion. Use GFCI fine, don't use GFCI fine, it's your choice.

Second, it only takes in the vicinity of around 5 +/- milliamps of current leakage to trip a GFCI and nuisance tripping can indeed be a problem as you have found. Moisture, dirt, contamination, insulation failure, material breakdown and other things can cause the trip. The GFCI may be working perfect and doing its job you know!!!!

If the current flowing in the ungrounded conductor on your heater isn't all being returned (within 5 +/- milliamps) by the grounded conductor (its leaking elsewhere), that can trip the GFCI. Such a fault/leakage path may or may not be easily determinable, depending on your test instrument. There should be like an open circuit (approaching infinity resistance on some meters) from the heater to electrical paths other then the grounded and ungrounded conductors. If there's a fault leakage path elsewhere that's conducting more then 5 milliamps, the GFCI is designed to trip.

Its common for inexpensive poor quality GFCI's to go bad, so you may want to try a new one if you fail to find that your block heater is defective. You might try a few manual test and resets as I have seen that help to some extent. Similar you may try to clean the heater and its plug and cord and connectors free of dirt or moisture that might help.

Finally, if you cant find a problem with the heater or it has no current leaks/faults (maybe try a different one) ,,,,,,,,,the GFCI itself isn't at fault (maybe try a new one),,,,,,,,,cleaning and test and resets don't help,,,,,,,,,, you can try a non GFCI if you choose.

NOTE a GFCI can be wired such that downstream outlets and connections after the GFCI are also protected, what's on your GFCI circuit at this time??? Do other appliances besides your block heater cause the GFCI to trip??? I take it she only trips when you plug a load into it correct???

Best wishes, hope this helps

John T

4 year old new wiring in basic shed, done to code.

First time any of the 5 outlets, 3 actual GFIC has tripped. Not that it matters but the outlet in use is plain, the actual GFIC is the one upstream. These are the only GFIC I have on the place, last construction before this building was the 1960s on this old place, heck most outletson this farm and house are 2 prong no ground. I'm frankly proud of myself for thinking of looking for a GFIC!

Circuit in question has been used for years for small fridge, winter cat water heater (I don't mind the GFIC protection....) and a winter electric fencer. Also used randomly for drill, battery charger, electric driver, and tank heater on the tractor.

First time its ever popped. Did so twice as soon as I plugged in the combine heater. Second time it popped all other loads were unplugged. Was planning on trying the other nearby circuit that has a different GFIC as soon as the tractor on that one is warm. I will guess it will pop, but never know.

I should wipe off the combine plug, been a lot of sweating and you know dust and grime in the endless fog we have had.

I presume there is indeed an issue with the block heater, just going through the checklist for now and the future. I suspect it might be difficult to detect a very small fault as you say.

Currently I am using the same cords and outlet that popped to power a 300 watt magnetic heater I put on the combine. Working fine.

I appreciate the answers and thurogh thoughts from everyone.

Paul

My experience is that is the first sign of a failing block heater. It seems to work fine if plugged into a regular outlet, but will trip a gfci. On a truck that is plugged in quite often, it can be most of a winter before the block heater goes. I would think one on a combine would last quite a long time yet, even though it is leaking electricity internally.

I don't know what specifically your issue is. That being said, I've had many GFCIs go bad. I'm in a house that was built new 15 years ago. I had to replace four GFCI outlets just this year that were tripping all on their own. Also had a GFCI breaker in the main-panel-box go bad. That was a Square D type Q0. A new one would cost $40. I eliminated it. I don't use GFCIs on anything that are plugged in to something important and need the power to be on. Like a battery maintainer, engine block heater, refrigerator, freezer, and/or animal water-heater. Note that a GFCI can trip on a circuit that is OK but has too long a run or capacitance.

I'm not trying to put ideas in your head. For me - NO GFCIs on anything that I rely on to be powered and it's not where I can see it. If you are a code-compliance worrier - NEC exempts most outdoor outlets If dedicated to one appliance. If you have a tractor that needs a block heater plugged in most of the winter, you can likely install a single receptacle and have it dedicated to the block heater and not be required to have a GFCI involved. But don't take my word for it. Read the NEC that has jurisdiction in your area (if you live in a code area). For myself, I don't care what some blow-hard says is "best" at the code-factory. I'll consider their suggestions and then use what suits my situation the best. I WOULD want to determine though that the block-heater is not defective in some way.

I ran into this with a hot tub heating element. My assumption was water had gotten into the element. Replaced the element, problem solved.

Paul, thanks for the feedback. I have lost count of how many GFCI's I've had go bad over the years and for no more then the cost or trouble maybe just try another one if resetting or cleaning or other things don't cure the problem. If she still trips and its only the heater that does it you found the problem for not all that much work or money.

There are a few NEC exceptions for items such as say a critical fridge or freezer kept maybe in a garage etc. and as I best recall the non GFCI's (exceptions) have to be in a normally NON accessible location like hidden away behind the freezer (NOT where its easy and normal to plug something in) plus they are single outlets NOT duplex receptacles.

Regardless of any NEC requirements or non requirements or your jurisdiction they are designed and where required TO SAVE A PERSONS LIFE so exercise good sound judgment in your decision to use one or not use one THE LIFE IT SAVES MAY BE YOURS OR A CHILD OR GRANDCHILD. Sure a lot of lay persons or non professionals or non engineers or electricians poke fun or make light of the NEC or even a GFCI but they do so at their own risk, as an electrical engineer I believe in them, but feel free to do as you please or what some Billy Bob may advise lol

Best wishes, keep safe yall even if you you're smarter then the panel of experts who make up the NEC board.

John T Long retired electrical engineer

(quoted from post at 10:54:37 12/26/14) My 4-5 year old shed, woulda been wired 4 years ago maybe, it was done to code. Not fancy, got 5 outlets in the building. Only building that has GFIC don't have a one in the house, but it is what it is. First time I've had anything bother with it. Actually I had to go look at the outlets to see if I even had it, checked the breakers and they were fine, took me 3 minutes to realize oh maybe.....

Think that is fairly recent that GFIC is code in storage buildings here.

Paul

Click to expand...

Paul, I would say that this is not a good use of "it is what it is". When GFIs first came out I went and got some and put them in kitchen bath and outdoors. After all they don't cost much, they are quick to install, and they save lives. Maybe even someone you care about.

I would agree with Ultradog, have had 15 amp GFCI's fail more often than 20A, I usually just put in a GFCI breaker now.

A circuit breaker and GFCI work differently.That's why your circuit breaker didn't trip.

Don't get to excited on replacing stuff. On humid days my tractor will pop the GFIC. Plug it in to a reg outlet and works as it has the last 30 years. When humidity is low it works with the GFIC, go figure. I have one circut non GFIC just for this reason.

GFCI. Easier than teaching the kids not to plug in the hair dryer then play with it in the bathtub.
I hate the things. One at the boss's shop you plug in an extension cord and it pops. Every time I have plugged into it even right after the outlet was installed. Longest I have seen it go without popping is 2 steps back toward the truck to plug in the battery charger.

I'd try plugging in to a non gfci outlet first. I have had trouble in the past as well, it seems like the block heater pulls a lot of power initially but once it gets cooking it's ok. Almost the same scenario as an electric motor draws more amps until it gets up to full speed.

I had this happen one one of my Kubotas. Replaced the heater and the new one started doing the same thing in short order. I cut the ground pin off the plug (I know the correct police will chastise me) and it has been working for 6 years. It also helps to mount the element with the electrical connection up.