Rod Oven pops GFI breaker

[Furu]

I recently acquired 3 Phoenix rod ovens (2 BVT models and 1 BHT models, 150 watts) off of Craig's list for a very nice price. The two BVT's work perfectly with variable thermostats. The BHT has a fixed thermostat.
The BHT model does not pop the main breaker but does pop the GFI breaker after about an hour or so of heating. Did not know but found on the internet a reference to electric heaters in general as they age having a problem with stray current loss (what GFI's detect and pop for to prevent electrocutions in the vicinity of water). The unit works fine on a non-GFI circuit. Of course code required GFI in garages, shops etc.
Being a bit leery I question whether the unit should be used or not. If the internet reference is correct a lot of our space heaters as they age will pop a GFI but we never know it if they are not used in the kitchen, bathroom or garage.
Parts are not available from Phoenix as they discontinued the model and parts for it in 2001.
I only really need one but they came together so I have three and will probably put the others on the shelf as backups since no parts are available. Just don't know if I want to use the BHT model or put it on the dustbin/parts bin.

[E/S]

You really need to put a amp meter on it to know for sure why the bracket trips.
For now I would keep it for parts/trade if you don't have a way to test it.

E/S

[Rock knocker]

Code requires the GFCI protected circuits be installed during construction. I don't know of any law that requires you as a homeowner to keep these circuits such as they are. You are perfectly in your rights to replace tham with a standard non-GFCI outlet or breaker.

Alternately, you could replace (or add) one or two 110v twist-lock outlets with a matching plug on the oven, to service only the oven. That way no now could be endangered by plugging into a u-ground and not being GFCI protected

[dstig1]

Gfis are known to get touchy with age, too. You may want to try another one first.

[k0ua]

This is entirely hypothetical, but is it possible that the problem is not age per se' but dust accumulation? could you take the unit apart and clean its heating elements of any dust that may be allowing a path to the shell of the oven for small leakage currents to flow to ground instead of back thru the neutral? This is just an idea, I have no experience with a rod oven, and for all I know you cannot take it apart.

James K0UA

[Furu]

This is entirely hypothetical, but is it possible that the problem is not age per se' but dust accumulation? could you take the unit apart and clean its heating elements of any dust that may be allowing a path to the shell of the oven for small leakage currents to flow to ground instead of back thru the neutral? This is just an idea, I have no experience with a rod oven, and for all I know you cannot take it apart.

James K0UA

That is a great idea.
I had it apart after I first found the problem and did replace a couple of connection wire crimps thinking they might be the problem as they and their shrink wrap was showing wear. At the time I thought that might have been the problem so put it back together. Still had the problem then found the reference to "old" elements leaking.
It is an outstanding suggestion. I will pull the heating elements and clean them. Even though the parts are not available I can remove the elements and try your suggestion. The odd thing is that it happens after the elements are/have been to temperature for about an hour.

Thanks

[k0ua]

That is a great idea.
I had it apart after I first found the problem and did replace a couple of connection wire crimps thinking they might be the problem as they and their shrink wrap was showing wear. At the time I thought that might have been the problem so put it back together. Still had the problem then found the reference to "old" elements leaking.
It is an outstanding suggestion. I will pull the heating elements and clean them. Even though the parts are not available I can remove the elements and try your suggestion. The odd thing is that it happens after the elements are/have been to temperature for about an hour.

Thanks

Also do a very close visual inspection for any carbon tracking on the insulators that might allow small currents to flow... Clean everything real well and see what happens. Can't hurt, and who knows might fix it.

James K0UA

[Furu]

This is entirely hypothetical, but is it possible that the problem is not age per se' but dust accumulation? could you take the unit apart and clean its heating elements of any dust that may be allowing a path to the shell of the oven for small leakage currents to flow to ground instead of back thru the neutral? This is just an idea, I have no experience with a rod oven, and for all I know you cannot take it apart.

James K0UA

Just an update.

James pretty much hit the nail on the head. After the one unit had the GFI issue I plugged it into the normal circuit and it ran well. After getting his suggestion I was going to pull the elements and clean them but got busy for a couple of days. Before I took it apart I tried the GFI circuit again. Well the first hour passed where it always popped and nothing then a day then another etc.. It had to be the dust and running it on the non-GFI for several days must have "burned" the dust off as no more problems. I will eventually open it up again to look but the problem has been resolved and runs fine on GFI circuits.

[k0ua]

Just an update.

James pretty much hit the nail on the head. After the one unit had the GFI issue I plugged it into the normal circuit and it ran well. After getting his suggestion I was going to pull the elements and clean them but got busy for a couple of days. Before I took it apart I tried the GFI circuit again. Well the first hour passed where it always popped and nothing then a day then another etc.. It had to be the dust and running it on the non-GFI for several days must have "burned" the dust off as no more problems. I will eventually open it up again to look but the problem has been resolved and runs fine on GFI circuits.

Yeah, gotta wonder if it burned off whatever piece of junk or dirt was making a high resistance leakage path to the shell (ground) of the appliance. Anyway glad it is working for you.. I could use one of them myself, but have been getting along OK with just my airtight storage holders.

James K0UA

[pat32rf]

If it is an exposed wire element (like in a dryer)there might have been dust on it but more likely it was a cal-rod element (like in a stove element) that had absorbed a bit of moisture during storage. Once it had a chance to run and dry out for a few days things became OK.
While not a fan of GFI's, they do have a purpose. If you remove one and down the road someone gets hurt you can kiss your butt goodbye....