Engine Block Heaters and GFI's

[A/A Fuel GTX]

I'm having a lot of problems with tripping GFI's on engine block heater circuits. Just wondering if anyone else has trouble with these and what the remedy is.

 

[Jim W in Tampa]

They have leakage or would not trip

 

[A/A Fuel GTX]

They have leakage or would not trip

Agreed but it is a constant problem. Perhaps a poor design in the manufacturing process that causes the imbalance. WI used to have an exemption for block heater receptacles but the current statutes require GFI's.

 

[Jim W in Tampa]

Agreed but it is a constant problem. Perhaps a poor design in the manufacturing process that causes the imbalance. WI used to have an exemption for block heater receptacles but the current statutes require GFI's.

Are they all one brand ? Likely china junk

 

[A/A Fuel GTX]

Are they all one brand ? Likely china junk

The brand doesn't seem to make a difference. Extension cords laying in the snow are often a factor but this happens without any snow on the ground too. Hey....whats a guy from Florida know about block heaters anyway

 

[Jim W in Tampa]

The brand doesn't seem to make a difference. Extension cords laying in the snow are often a factor but this happens without any snow on the ground too. Hey....whats a guy from Florida know about block heaters anyway

Was raised near Pitsburgh Pa. Thankfully had the sense to leave it early in life.
Would question even moisture in air to be enough to trip them. We used the 100 watt lightbulb trick but that was back in 72 . Found out i can stay warm and live just as good in FL.

 

[iceworm]

I'm having a lot of problems with tripping GFI's on engine block heater circuits. Just wondering if anyone else has trouble with these and what the remedy is.

Well, I do have a lot of time in looking at engine heater circuits.

First, I agree with Jim. The circuits are tripping because there is more than 5ma leakage. If it is the vehicles and they are POVs, not much you can do except identify and ban them until repaired. If it is commercial vehicles. they are captive and you can measure the leakage on each one - and get the offenders repaired.

Here is a list I would start with:
1. GFCI receptacles or CBs?
2. At the vehicle end - are you using receptacles, or cold weather cord and cord caps?
3. Which circuits are tripping? Is is random or always the same ones? Does it follow certain vehicles?
4. Do the cords stay plugged in to a receptacle or do the cords go with the vehicles? Are the spaces assigned?
5. Does the installation include thermostats and timers to cycle the outlets based on ambient?
6. More than one outlet per circuit?
7. About how many broken receptacles, covers, or cordcaps do you replace each season?

Give us some answers on these. Maybe there will be some clues.

For checking the vehicles, I built a small test adapter using a 50:5CT, 1000ohm resistor, 5 feet of #16SO, male and female cord caps, and a fluke 87. It wasn't very accurate, but I could see which ones were the offenders.

ice

 

[Jim W in Tampa]

Well, I do have a lot of time in looking at engine heater circuits.

First, I agree with Jim. The circuits are tripping because there is more than 5ma leakage. If it is the vehicles and they are POVs, not much you can do except identify and ban them until repaired. If it is commercial vehicles. they are captive and you can measure the leakage on each one - and get the offenders repaired.

Here is a list I would start with:
1. GFCI receptacles or CBs?
2. At the vehicle end - are you using receptacles, or cold weather cord and cord caps?
3. Which circuits are tripping? Is is random or always the same ones? Does it follow certain vehicles?
4. Do the cords stay plugged in to a receptacle or do the cords go with the vehicles? Are the spaces assigned?
5. Does the installation include thermostats and timers to cycle the outlets based on ambient?
6. More than one outlet per circuit?
7. About how many broken receptacles, covers, or cordcaps do you replace each season?

Give us some answers on these. Maybe there will be some clues.

For checking the vehicles, I built a small test adapter using a 50:5CT, 1000ohm resistor, 5 feet of #16SO, male and female cord caps, and a fluke 87. It wasn't very accurate, but I could see which ones were the offenders.

ice

That would handy for a lot of gfi problems. Why the 1k

 

[iceworm]

That would handy for a lot of gfi problems. Why the 1k

Well, the short answer is that 1K gives me a 5V output for a 5ma leak.

I used a 50:5 because that was what I had in the junkbox. So, stripped back the SO in the middle couple of feet, and cut the green. Wrapped 10 turns of the black and white around the CT window. Butt spliced the green together outside of the window. Put a cordcap on each end of the SO. Connected the 1k resistor across the CT output. Connect the DVM across the resistor.

The only reason I made the adapter up was to "prove" to the vehicle owners they had a problem. Their response was usually, "But it doesn't trip at home." Then you pull out the "prover" and show them. Other than that I pretty well tend to believe the receptacle or the CB. And, they are easy enough to change if they are suspect.


ice

 

[Jim W in Tampa]

Well, the short answer is that 1K gives me a 5V output for a 5ma leak.

I used a 50:5 because that was what I had in the junkbox. So, stripped back the SO in the middle couple of feet, and cut the green. Wrapped 10 turns of the black and white around the CT window. Butt spliced the green together outside of the window. Put a cordcap on each end of the SO. Connected the 1k resistor across the CT output. Connect the DVM across the resistor.

The only reason I made the adapter up was to "prove" to the vehicle owners they had a problem. Their response was usually, "But it doesn't trip at home." Then you pull out the "prover" and show them. Other than that I pretty well tend to believe the receptacle or the CB. And, they are easy enough to change if they are suspect.


ice

Not sure if i understand. Can you draw us a diagram ? Would think you need 2 coils like we have in a gfi receptacle

 

[A/A Fuel GTX]

1. GFCI receptacles or CBs?

Receptacles

2. At the vehicle end - are you using receptacles, or cold weather cord and cord caps?

Cold weather 14-3 cord, standard cap plugged into a GFI recept.

3. Which circuits are tripping? Is is random or always the same ones? Does it follow certain vehicles?

Random trippage, Random vehicles.

4. Do the cords stay plugged in to a receptacle or do the cords go with the vehicles? Are the spaces assigned?

Cords stay plugged into the receptacle, spaces are assigned.

5. Does the installation include thermostats and timers to cycle the outlets based on ambient?

No stats or timers, heaters are energized when cord is plugged into recept.

6. More than one outlet per circuit?

Yes, two duplexes per circuit

7. About how many broken receptacles, covers, or cordcaps do you replace each season?

None, not an issue.

 

[Jim W in Tampa]

Your adding to the problem if sharing gfi receptacles. They might all have lets say 2 ma and alone would no trip but 4 of them easily puts you over.
How is the plug being protected while driving ? Water might be getting in the plug.

 

[A/A Fuel GTX]

How is the plug being protected while driving ? Water might be getting in the plug.

It's a molded plug that is part of the factory produced block heater.

 

[kwired]

Well, the short answer is that 1K gives me a 5V output for a 5ma leak.

I used a 50:5 because that was what I had in the junkbox. So, stripped back the SO in the middle couple of feet, and cut the green. Wrapped 10 turns of the black and white around the CT window. Butt spliced the green together outside of the window. Put a cordcap on each end of the SO. Connected the 1k resistor across the CT output. Connect the DVM across the resistor.

The only reason I made the adapter up was to "prove" to the vehicle owners they had a problem. Their response was usually, "But it doesn't trip at home." Then you pull out the "prover" and show them. Other than that I pretty well tend to believe the receptacle or the CB. And, they are easy enough to change if they are suspect.


ice

Why not just check them with a megohmmeter? Works very well at finding ground faults.

One thing I have found a few times before that is a common bad practice is to put an extension on the cord of the engine heater to lengthen it and not seal the splice to keep water out of it.

 

[Cold Fusion]

So:
Two GFCI duplex receptacles per circuits? One vehicle plugged into each receptacle - two vehicles per circuit?

The cord is a factory made up extension cord that stays plugged into the GFCI receptacle.

Spaces are assigned - always the same vehicle in each space.

Random trips. Can't limit trips to specific circuits, vehicles, cords.

And since you are using GFCI receptacles, can't even be under ground wiring.

Customers are careful and are not tearing up the cords or receptacles.

I'd say you have touched on all of the easy troubles and most of the not-so-easy. Hopefully this will teach me to not mouth off just because I happen to have a lot of experience on a particular subject.

My preference is to use a GFCI cb feeding a single duplex nylon federal spec receptacle. Then I get cords with a factory lighted end. Or a GFCI cb feeding a 5 foot Arctic grade cord, hard wired into a box at the pedistal with a strain relief. Use a lighted highend rubber cord cap on the vehicle end of the cord. But that is to alleviate the customer caused damage (drive-offs) And you don't have that.

As jim said, on circuit per vehicle is good. But that's not something you can easily change. So that is not available. Still, as jim also mentioned, two GFCI receptacles on each circuit would cut down on the two vehicles ganging up on one GFCI feeding a second receptacle.

I have not ever seen rain or snow cause any trouble. Still, maybe cord hangers at each pedistal to keep the cord ends up out of puddles and away from the snow plows. But you're not changing any cord ends, so the plows are not causing any trouble.

Maybe a better grade of GFCI. I think a nylon federal spec is available.

Only thing left is to start checking the vehicles. It seems unlikely that there are several vehicles hovering on the verge of tripping and randomly drifting over the GFCI limit - but possible.

After that, I'd start looking at bad karma on your part.:roll:

ice

 

[Jim W in Tampa]

You could keep the circuits but wire in a seperate gfi receptale for each heater. That stops the leakage from adding up. Be sure they all have a quality gfi and an inuse cover. If still triping than they likely are defective. Find a way to keep the cord plugs dry. Even a bit of water between the prongs along with dirt or grease could trip. Bottom line is every part of this must be perfect. Yes will be costly.