Block heater GFI protection

[WirenutNH]

I have a customer in Woburn Ma that has diesel trucks that they plug in during the cold weather. My thought is that these 20amp 125v outlets need to be GFI protected as they are located outside in a parking lot. They have had instances when the GFI have tripped and they can?t start their trucks in the morning. They want to remove the GFI?s and install duplex outlets so that they don?t trip. I have research if this would be feasible to do and can?t find anything that says this would be acceptable. Any thoughts would be great.

 

[LEO2854]

I have a customer in Woburn Ma that has diesel trucks that they plug in during the cold weather. My thought is that these 20amp 125v outlets need to be GFI protected as they are located outside in a parking lot. They have had instances when the GFI have tripped and they can?t start their trucks in the morning. They want to remove the GFI?s and install duplex outlets so that they don?t trip. I have research if this would be feasible to do and can?t find anything that says this would be acceptable. Any thoughts would be great.

I would not take on that liability, why it is even being considered makes me wonder what this guy is thinking, check the wiring and install new Type WR GFCI's that is probably all this guy needs, who knows, the old ones are probably 20 years old....Also give him an OSHA safety book

 

[Electric-Light]

I have a customer in Woburn Ma that has diesel trucks that they plug in during the cold weather. My thought is that these 20amp 125v outlets need to be GFI protected as they are located outside in a parking lot. They have had instances when the GFI have tripped and they can?t start their trucks in the morning. They want to remove the GFI?s and install duplex outlets so that they don?t trip. I have research if this would be feasible to do and can?t find anything that says this would be acceptable. Any thoughts would be great.

Such a bad idea. The GFI is most likely tripping for a valid reason like moisture creating a leakage path to the ground conductor. If there's a chaffed cord brushing up against something like chromed grille that do not connect to the body, it will become live. If someone touches it, they'll get shocked. GFI will shut off the power. If there's no GFI, the risk of harm is inceased.

 

[ceb58]

they are located outside

That tells you everything you need to know. No way around the requirement.
You could install GFCI breaker(s) for the circuit(s).They are not as subject to nuisance tripping as the receptacles

 

[big john]

...You could install GFCI breaker(s) for the circuit(s).They are not as subject to nuisance tripping as the receptacles

I feel like this is electricians' folk-lore. I hear it a lot, but as far as I know all class A GFCIs follow the same trip curve.

 

[ptonsparky]

Get your megger out and check each truck heater. Red tag the units that fail.
. Check the extension cords.
Make sure proper covers are on the devices after you upgrade to the WRs as suggested.
Do everything but remove GFCI protection.

 

[Cow]

I agree with megging the trucks. Show them there is in fact a problem with the truck, not the GFCI.

 

[Electric-Light]

I agree with megging the trucks. Show them there is in fact a problem with the truck, not the GFCI.

I wouldn't. The cause can be as simple as wire rub-through from heat block plug-cord wire rubbing through another wire. That wire can be a sensor wire. If you megger it, you can fry electronics.

 

[ptonsparky]

I wouldn't. The cause can be as simple as wire rub-through from heat block plug-cord wire rubbing through another wire. That wire can be a sensor wire. If you megger it, you can fry electronics.

What do you think the 120v would be doing to it when the GFCI is removed?

"Dead" or maybe highly unlikely "fried electronics". Decisions, decisions.
If your checking the block heater, check the cord too.

 

[iwire]

What do you think the 120v would be doing to it when the GFCI is removed?

"Dead" or maybe highly unlikely "fried electronics". Decisions, decisions.
If your checking the block heater, check the cord too.

Typically it will be an insulation breakdown of the heating element and the EGC would keep things safe.

That said I would not even think of removing the GFCI protection.

If it was a true hard short either line to line or line to ground it would be tripping the breaker as well as the GFCI.

 

[Cow]

I wouldn't. The cause can be as simple as wire rub-through from heat block plug-cord wire rubbing through another wire. That wire can be a sensor wire. If you megger it, you can fry electronics.

I'd say the odds of that versus it being rubbed through against the frame or even more likely, a heater element that is breaking down is far more likely. Nonetheless, I'd still be willing to take the chance and megger it if I had too.

 

[iwire]

With any block heater I have seen it would be very simple to just physically follow and visually inspect the line voltage cord all the way from cord cap to element.

If the line cord was shorted to the frame of the truck it would trip the breaker along with the GFCI. (Assuming intact EGC which I would not assume)

All it takes to trip a GFCI is a bit of leakage current from the elements to the coolant. We all know this is a common occurrence with electric water heaters.

 

[ceb58]

I feel like this is electricians' folk-lore. I hear it a lot, but as far as I know all class A GFCIs follow the same trip curve.

I have found that there are situations where the GFCI receptacle is in a high use area and because of the, for a lack of a better term, abuse that they are subject to more false trips. Where a breaker, for the most part, is in a more controlled environment.
Also if there is more than one truck plugged in at the same time it could be a combination of the two leaking enough current to trip the GFCI where one by its self would not.

 

[big john]

I have found that there are situations where the GFCI receptacle is in a high use area and because of the, for a lack of a better term, abuse that they are subject to more false trips. Where a breaker, for the most part, is in a more controlled environment....

Gotcha. So it's not a difference in sensitivity, it's just that there's likely to be less moisture and contamination directly influencing the GFCI itself.

The only caveat I'd add to using GFCI breakers is that you then can have problems with cumulative leakage in the circuit: I have definitely seen GFCI breakers trip when on long circuits where the same cord-connected load would not trip a GFCI receptacle located at the far end.

 

[ptonsparky]

One truck heater per GFCI and depending on wattage, one per circuit.