tractor trips GFCI outlet....help

woodlot · Mar 6, 2007

Hi, I'm hoping someone can help me solve a problem I'm having. I own a ford/new holland model 1920 tractor, its a 1997. Anyway, I can't plug the block heater in without tripping the GFCI outlet in my barn. I removed and inspected the block heater cord and it has no cuts, frays, or anything that would indicate a short to ground. The block heater is installed in a freeze-plug port on the side of the engine block. Why would my GFCI be tripping and how can I fix this? Thanks!

rback33 · Mar 6, 2007

Is that the only outlet or are there more in a series after that outlet? If there are more, then you are drawing too much between ALL the outlets and that is causing it to trip. I have this same issue with the outlets in my shed. My guess is you have tank or buckets heaters plugged in elsewhere in the circuit that are overloading it.

Soundguy · Mar 6, 2007

Is the block heater using hot/ground or is there a hot /neutral miswire on the plug or receptical. A cheapy electrical outlet tester will tell you if there is miswire at the recep.

Any chance it is just too much of a load? have you tried it in another recp not on gfci but with same amperage breaker.. OR on a gfci not on a sub panel ( like at your house / garage? ).

Sounds like the gfci is sensing ground current and tripping.

Only other time I saw this was with a sears freezer i had in my garage that, if power went off, would trip the gfci when power came back on.. A real PITA.. i eventually wire dthe freezer up to a REAL plug after throwing out the contents for the 2nd time..

Soundguy

rback33 · Mar 6, 2007

Soundguy said:
Is the block heater using hot/ground or is there a hot /neutral miswire on the plug or receptical. A cheapy electrical outlet tester will tell you if there is miswire at the recep.

Any chance it is just too much of a load? have you tried it in another recp not on gfci but with same amperage breaker.. OR on a gfci not on a sub panel ( like at your house / garage? ).

Sounds like the gfci is sensing ground current and tripping.

Only other time I saw this was with a sears freezer i had in my garage that, if power went off, would trip the gfci when power came back on.. A real PITA.. i eventually wire dthe freezer up to a REAL plug after throwing out the contents for the 2nd time..

Soundguy

I had a similar freezer issue.... except it was empty and I was trying to move it back into the house after that part of the remodeling was done. I hosed and scrubbed on since it was filthy before moving it into the house. It would run about 30 seconds and trip the GFCI outlet. Fourth time I gave up and plugged it into an adjacent regular outlet, knowing that the issues was moisture related from the cleaning. Sure enough it ran fine there and about three days later I plugged it back into the GFCI and it has been fine ever since.

ultrarunner · Mar 6, 2007

There is a slim chance the GFCI is defective.

The quality and price of GFCI's receptacles vary from less than $10 to over $100 for Hubbell's Heavy-Duty Hospital Grade #GF8300WA.

shaley · Mar 6, 2007

Wow, I have a NH 2120 and last Dec. my block heater was doing the same thing. I plugged it in to a non GFI extension cord and it seemed to heat for about a day. Bad move. There was water behind the half moon plug at the block heater. It proceeded to electrolyse the copper heater pin away and ruined the unit. If the GFI is not tripping from moisture, chanches are the heater element is breaking down and you have a true fault to ground. It only takes 5 mA to trip a GFI. I'd test it on another GFI circuit to make sure it's not juat a bad GFI. Anyway, it is probably is a 400w 120v made by Zerostart. Mine is a 40mm dia. and NAPA had it for $40 but it came with a 5ft cord set. Advance Auto has the KATS for about $16 but wasn't sure if the cord was the same and I wanted to use my 1ft cord. Measure the freeze plug hole dia on a plug you can get at on the engine and see what size you need.

woodlot · Mar 6, 2007

Thanks for the replies. The one thing I can say forsure is that this is not a GFCI problem. This is a dedicated circit and the GFCI itself is a hi-grade Pass&Seymor. I'm pretty sure that there is a fault.

How hard it it to replace the heater? What's the procedure to get that bugger out & get a new one in? FYI, my heater has about a 5 foot cord and a "1/2 moon" shaped fitting between the cord and heater.

Diesel-ME · Mar 6, 2007

Woodlot,

After you test the heater on a different GFCI outlet (making sure that there is no other load on that circuit), it's safe to assume that the heater is going bad. I had the same thing happen on my PowerStroke. You can probably get away with plugging in to a non-GFCI for a while, but it should be easy enough to replace the heater. Heck, maybe you can ride out the balance of winter and put it off until fall....manyana.....

In any case, if you can get someone else with the same setup to measure the resistance of a known-good heater you could compare. Any cheap-o Ohm meter would work for this. I'd just measure from hot and neutral to ground.

~paul

shaley · Mar 6, 2007

Measure the plug diameter of the one next too it. The freeze plugs are slightly recessed and the bore can be measured with a caliper. They make a 39mm, 40mm, and a 41mm. In inches, this is only 0.040" difference so a tape measure will not be accurate enough. I can post the NAPA part # for the 40 mm. Meanwhile I'll go look at the shop manual and see if it has 1920 data.

_RaT_ · Mar 7, 2007

GFCI's trip not from current overload but by loss of electrons. Basically the GFI counts the electrons going in and counts what comes back allowing a margin of loss. I would take a ohm meter and test the heater coil by putting one lead to the coil and the other to the tractor on clean steel. Do both sides of the coil. If you get a reading (lower the number the less resistance the more loss), you heater coil is shorting to the tractor.

Bobvt · Mar 7, 2007

My GFCI outlets (on 2 different circuts) will trip if I plug my tractor in. I believe they are 15 amp GFCIs. Have to run an extension cord to a non GFCI oulet. On my previous tractor I had a 1000 watt heater and it would work fine on the GFCI. When I replaced the heater with a 1500 watts unit, it would blow the circut.

Bob

_RaT_ · Mar 7, 2007

Bobvt said:
My GFCI outlets (on 2 different circuts) will trip if I plug my tractor in. I believe they are 15 amp GFCIs. Have to run an extension cord to a non GFCI oulet. On my previous tractor I had a 1000 watt heater and it would work fine on the GFCI. When I replaced the heater with a 1500 watts unit, it would blow the circut.

Bob

Do these heaters always stay on? I am aware of block heaters, just have never needed one.

shaley · Mar 7, 2007

Block heaters are direct wired and have no T-stat. They just heat the water jacket to whatever the outside temp will allow. If I plug mine in on a 70 deg day the block is about 115 deg in about 3 hrs. I try to use mine only when the temp is below 40 deg. I have a 400w in a 160cu in. engine. I think my Dodge Cummins uses a 800w so a 1500w unit could cause some problems if it was left plugged in.

_RaT_ · Mar 7, 2007

shaley said:
Block heaters are direct wired and have no T-stat. They just heat the water jacket to whatever the outside temp will allow. If I plug mine in on a 70 deg day the block is about 115 deg in about 3 hrs. I try to use mine only when the temp is below 40 deg. I have a 400w in a 160cu in. engine. I think my Dodge Cummins uses a 800w so a 1500w unit could cause some problems if it was left plugged in.

I would think it would be expensive to operate. 1500 watts is going to show up on the electric bill. A 1500 watt element can be operated continuosly by a 15 amp breaker provided there is nothing else on that circuit. We use the 80% rule of thumb, that is, a breaker/circuit should be designed to continuously handle 80% of its rating with no problem. That gives 1440 watts on a 15 amp 120V circuit of reliable power to the heater. 1500 is close enough.

SpringHollow · Mar 7, 2007

My 15 year old block heater on my 2120 just started tripping my GFCI outlet about a month ago. I checked the outlet and it was working fine. I replaced the heater with a new one and everything is fine.

Ken

woodlot · Mar 7, 2007

Here's the numbers on the block heater. I measured these data last night in a dark, cramped, very cold barn, so I hope there accurate.

First what I could read on the face of the block heater: Made in Canada; LR1843; x00 watts (I could not read the first digit).

Then the resistance measurments. I measured between the two outter pins and the center pin on the heaters fitting. I assumed the center pin was ground. I got strange readings. I put a prode on the first outter pin, and the other probe to the center pin and my meter showed 1.5 M-ohms and then resistance increased as I held the probes on the pins. I held the probes for about 30 seconds and got up to 2.1 M-ohms. The reading was still increasing but thats all the longer I could hold the probes. The second outter pin -to- center pin reading was the same, it started at 1.4 and increased to 2.0 M-ohms after approx. 30 seconds.

Finally the freeze plug port next to the heater measured 1.575 inches ID.

What's the diagnosis?

shaley · Mar 7, 2007

Well, 1.575 is 40mm. I can't really say about the ohm meter readings. You really need a "megger" to check leakage current to ground.
The NAPA P/N is 605-3032. You might see if they have a unit W/O a cord. The cord is about $20 of the total $45 cost.
Just drain the coolant and unscrew the center screw and the unit will pull right out. The unit has a butterfly tab similar to a toggle bolt which the center bolt will expand after the heater is inserted.

Bobvt · Mar 7, 2007

I don't think my block heater (or ones on previous tractor) had a thermostat. I don't leave my tractor pluged in all the time. The 1500 watt versus the 1000 cut the the wait time in half (e.g. 10 below, approx. 50 minutes with 1000 watt and about 30 minutes with 1500 watt). This morning it was 21 below, took almost an hour before tractor would start.

While a non GFCI 15 amp breaker (1800 watts) can handle 1500 watts, the 15 amp GFCIs are more sensitive to changes in the draw. Plugged in to a GFCI, the heater will run for about 2-3 minute before tripping.