GFCI issue w/ block heater

[DZink24]

recently i have been having issues with the GFCI outlet in my garage when plugged into the block heater. i have a heavy duty 100' yellow jacket 3 prong electrical cord and sometimes it trips several seconds into being plugged in. what could be the issue? possibly a cut in the jacket, causing an exposed wire, or maybe condensation on the male end of the heater cord? i have checked the entire lenght of the cord for defects, and found none that are out of the ordinary, and i try to get any snow or ice on the prongs dried off before plugging in. the reason that i am so stumped, is that sometimes everything works flawlessly, and othertimes it is a disaster.

 

[kenny61]

GFCI's make sure that what ever current goes in one flat comes out the other flat. You can use an ohm meter and check that there is no conductivity between eithr of the flats and the round ground plug. That will tell you if the cord is bad , wet or whatever that can cause the GFCI to trip

 

[Hoefler]

Check the cord on your truck from the plug to the heating element, it could be cut, chaffed, or the element could be bad.

 

[d6c]

Was around an ambulance that could not be plugged in to shore power if it was a gfci... try a non-gfci outlet... bet it will work just fine... . too much internal cross-talk will trip a gfci everytime... .

 

[CKelley1]

get rid of the gfi, it only takes about three minutes to change

 

[DZink24]

thanks for the replies. to add to the confusion, last night, the circuit tripped, and i did not even have the truck plugged in, only the trouble lamp. i see i forgot to say originally that i have this on a timer set several hours before leaving and also have a small trouble lamp hooked into the timer so the wife can see what shes doing as she loads the boy into the car.

 

[BK]

yea, ditch the GFCI. there could be leakage current from the heating element to the block.

The ground of the cord set is grounded to the truck.

The GFCI trips at about 5ma of leakage current.

When mine was new, and I know it was fine, it would trip.
replaced the gfci outlet, did it again in due time.

I run it off of an X10 module for timer and easy on and off.
I now source it from a non-GFCI outlet.

 

[StephenBailey]

After 3 seasons of winter use, block heater began to trip GFI outlet. Swapped out extension cord, then GFI, then heater cord with no luck. Ordered new block heater from Geno's. Installed today and no tripping of GFI. Coolant looked nice and clean. Buildup of some kind on old block heater (does not appear to be mineral). Deposits sticky paste in nature. #ad

 

[mwilson]

My GFCI has tripped the last two nights when timer comes on at 2. 00am.



Went out tonight to try to get it working right as I don't like starting the 12-valve at -5 to -10 below with a stone cold block... .

Still tripped everytime I applied power.



I felt the calcium/road chemical mixture dripping off of the plug might be causing the issue so I took a can of WD-40 outside and blasted the cord end and the socket end of the extension cord. Wiped off excess, plugged it back in and applied power again.

Works fine now!!!!



Calcium must be conductive enough to allow a trickle of power across the plug.

If you are having this issue give the WD-40 a try before you tear the GFCI out.



I have a new cord and socket ready to install but I don't think I need it now.



Mike

 

[PBJ2500CTD]

thanks for the replies. to add to the confusion, last night, the circuit tripped, and i did not even have the truck plugged in, only the trouble lamp. i see i forgot to say originally that i have this on a timer set several hours before leaving and also have a small trouble lamp hooked into the timer so the wife can see what shes doing as she loads the boy into the car.

Is the timer electronic or mechanical; two wire or three wire; installed pre or post gfci? It could be tripping due to the circuit loading and/or switching of the timer. Try removing the timer from the circuit to see if that resolves your problem. It may even be a bad gfci circuit.

 

[mwilson]

Two trucks fighting over one extension cord... at -10 below... :-laf

 

[DZink24]

it has seemed fine the past few days. i will try the WD 40, as there does seem to be some corrosion on the heater plug. it actually tripped the outdoor GFCI at work last week, but i will say that must have been due to water. the timer at home is one of the mechanical ones. and in a related question, does (or can) a GFCI prevent a fire? if there was ever a problem and the circuit trips, the plug becomes dead at that point, eliminating any sparking or heat?

 

[PBJ2500CTD]

For the curious - Here are a couple of web sites explaining the GFCI theory of operation:

RV Electrical Safety: Part X ? GFCI Testing | No~Shock~Zone

http://www.nfphampden.com/gfci.pdf

 

[BK]

GFI's main reason for being is to detect low levels of "fault" current between the source and ground, it detects levels below what is thought to cause electrocution in humans. .
and when detected it opens the circuit.
So nuisance tripping do happen.

(huge product liability in manufacturing and selling such a safety device as a GFI's, so you know they'll error on the side of caution with any parameters)

As well, they just tend to trip out of "no where" with age...

The regular circuit breaker or fuse in your distribution panel, it's main goals is to protect against fire.

 

[DieselDoghouse]

Recently experienced the same sort of trouble. Went to a non-gfci this way. We recently moved, on the new garage I mounted a non-gfci outlet 7'6" above the ground-NEC and local codes require any outlet within 6'6" of the ground or conductive floor be gfci. This outlet is remote control (see x-10 powerhouse) with an indicator added. Adjacent control pad allows me to plug the 'tether' cords in dead (serves the dodge and wife's diesel Libby). Alternate keypad in house allows me to kick em on when it's frigid, by go time they've heated 2 hours and it's all good!

 

[jmsokol]

After 3 seasons of winter use, block heater began to trip GFI outlet. Swapped out extension cord, then GFI, then heater cord with no luck. Ordered new block heater from Geno's. Installed today and no tripping of GFI. Coolant looked nice and clean. Buildup of some kind on old block heater (does not appear to be mineral). Deposits sticky paste in nature. #ad

I'm Mike Sokol, the author of the NoShockZone.org electrical safety articles linked to here about how GFCI's work. Very interesting thread... I'm currently running an experiment determining if hot-water heater elements with a pin-hole leak from corrosion will produce Hydrogen-Oxygen gas from electrolysis. I believe that the cruddy looking element in the posted picture has a leak which is allowing current to flow into your cooling system water. Now, if you have a GFCI, that will trip around 5mA of leakage current. But if you bypass the GFCI and allow the corroded element to keep conducting to the water, then it will be producing Hydrogen-Oxygen gas in the perfect 2:1 ratio to cause an explosion if ignited. I'm not sure how you would ignite it internally, but certainly a spark in the block heater element is a possibility. My current experiments show that it takes about an hour for a corroded hot water heater element to make a cubic inch of H2-O2 gas, and this will rise to the top of the water source. Of course, some of it will dissolve, but most of it will be in a gaseous state. Now, I'm not sure if this could cause an explosion, but I'm not betting against it either.



Another danger that I am sure happens is when an engine block heater with a corroded element is plugged into an ungrounded extension cord or outlet. The entire truck's body and frame will be elevated to between 60 and 120 volts above ground. Touch the door handle of your truck while standing in water and it can certainly shock you and possibly cause death by electrocution. So if you feel the slightest tingle will touching your truck that has a block heater plugged in, then stop what you're doing and find the source of the voltage. The simplest way to check for a hot-chassis on your truck is to use a Non Contact Voltage Tester (NCVT) such as a Fluke VoltAlert. I use the 90-1000 volt version which will easily detect a hot-chassis voltage on the truck down to 40 volts. Here's the NCVT that I use and it's never let me down: http://www.amazon.com/Fluke-1AC-A1-II-Volt-Alert-Non-Contact-Voltage/dp/B000EJ332O



Here's a link to me testing a miniature RV with a NCVT for a hot-skin voltage condition: http://www.noshockzone.org/rv-electrical-safety-part-iv-–-hot-skin/ and http://www.youtube.com/watch?v=Y8h64X33aKg



Please contact me with any comments or questions about this situation. I'm interested in including information on block heater electrical safety on my website www.noshockzone.org and video channel at www.youtube.com/howtoseminars



Mike Sokol

-- email address removed --

www.noshockzone.org

 

[GCroyle]

Mike Sokol,



Watched the RV Hot Skin video, interesting stuff. Q. Can the hot skin test be performed with a common DVOM?



Thanks,



Gary

 

[jmsokol]

Mike Sokol,
Watched the RV Hot Skin video, interesting stuff. Q. Can the hot skin test be performed with a common DVOM?

Thanks,
Gary

Yes, but you'll need to check voltage between the chassis/body of the truck and a known-good ground connection. A short ground rod (18 inches of copper pipe or rebar) in the wet ground would be sufficient for this test. Anything more than 2 or 3 volts AC above earth ground is suspicious.

One other thing to watch out for is old garage outlets that have been mis-wired with something I call a Reverse Polarity Bootleg Ground (RPBG). This occurs when an old ungrounded outlet has been "upgraded" to a grounded outlet by installing a jumper between the ground and neutral screws. Now, if the black and white wires are properly connected inside the wall, then the outlet will be safe (but in violation of code). However, if the black and white wires have been accidentally reversed inside the walls, then you have the Ground and Neutral contacts at 120-volts and the Hot at ground voltage. While the appliance, RV or truck block heater will appear to operate properly, the entire body of the appliance or vehicle will be hot-skin electrified to 120 volts with 20 amps of fault current available.

Note that you can't find an RPBG outlet with a 3-light outlet tester, a $300 Ground Impedance Tester, or even a DMM (Digital Multi-Meter) testing between H-N, H-G and G-N contacts. All readings on an RPBG outlet will appear normal even though the ground and neutral are at 120-volts above earth. See http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html for an article I wrote about this condition, and http://www.youtube.com/watch?v=iLk-6pvSlWg for a video of how to use a Non Contact Voltage Tester (NCVT) to find it.

Mike Sokol
-- email address removed --
www.noshockzone.org

 

[PBJ2500CTD]

Yes, but you'll need to check voltage between the chassis/body of the truck and a known-good ground connection. A short ground rod (18 inches of copper pipe or rebar) in the wet ground would be sufficient for this test. Anything more than 2 or 3 volts AC above earth ground is suspicious.

One other thing to watch out for is old garage outlets that have been mis-wired with something I call a Reverse Polarity Bootleg Ground (RPBG). This occurs when an old ungrounded outlet has been "upgraded" to a grounded outlet by installing a jumper between the ground and neutral screws. Now, if the black and white wires are properly connected inside the wall, then the outlet will be safe (but in violation of code). However, if the black and white wires have been accidentally reversed inside the walls, then you have the Ground and Neutral contacts at 120-volts and the Hot at ground voltage. While the appliance, RV or truck block heater will appear to operate properly, the entire body of the appliance or vehicle will be hot-skin electrified to 120 volts with 20 amps of fault current available.

Note that you can't find an RPBG outlet with a 3-light outlet tester, a $300 Ground Impedance Tester, or even a DMM (Digital Multi-Meter) testing between H-N, H-G and G-N contacts. All readings on an RPBG outlet will appear normal even though the ground and neutral are at 120-volts above earth. See http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html for an article I wrote about this condition, and http://www.youtube.com/watch?v=iLk-6pvSlWg for a video of how to use a Non Contact Voltage Tester (NCVT) to find it.

Mike Sokol
mike@noshockzone.org
www.noshockzone.org

Mike,

Yes-siree... I have done the heebie-jeebies dance on occasion in some older campgrounds when I tried to open the trailer door on a wet rainy day. One campground had a number of sites wired in reverse AND no ground. They were undergoing a major utilities renovation. Dang that smarted! I immediately reported this to the office and requested a different site. They apologized and set us up in a better and properly wired site. (They said they were going to can their "electrician" as there is NO EXCUSE to "temporarily wire" things incorrectly. ) I now test each site BEFORE hooking up.

Hydrogen gas may indeed be produced. However, I wonder if a quantity large enough to cause an explosion would occur in the cooling system as most of it would be bled off in the coolant recovery system during normal operation and be no more dangerous than the batteries under the hood. Maybe other chemical reactions could occur, hastening deterioration of some components. It would be great to hear about your results.

Thanks for your detailed articles and input. Looking forward to more.

 

[GCroyle]

Mike,



Thanks, that's not a simple portable technique like the Fluke you demonstrated. Watched several of your youtubes and the common light plug in tester, got one too, just like everyone else. Need to be more carefull. I also hardwired a 30A surge protector into my trailer. In a couple of weeks we have a gang of about 30 rigs getting together, Sounds like the safe approach is to Fluke test the pedestal first, correct? I already lost a 30A shoreline pedestal plug at a campground already. I might have a Fluke by then and be the guy going around.



Do you work for a related RV, electrical or other company?



Thanks,



Gary