Heater element tripping GFCI

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  #1  
Old 05-13-15, 10:16 PM
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Heater element tripping GFCI

I'm trying to get a sauna heater running in a new sauna we have here and am having problems. I have two old heaters which are both showing similar properties we'll call it for now (maybe problems once it's clarified)...

The first heater ran for a few minutes then tripped the GFCI. The GFCI wouldn't rearm after this (instantly trips). I pulled it apart and tested continuity around the two elements, and continuity to ground, finding there was a varying resistance of 10K-150KΩ ohm between the element terminal and ground. So I decided this was the source of current leakage, faulty element, onto heater number 2.

I wired heater number 2 to test it and it roasted nicely. I got to work cleaning it up, sprayed the element and grill with water to clean and then properly installed it. Upon powering up this time it tripped the GFCI. So I checked the elements of this heater. I'm finding a similar result.
Of the two elements, the top one isn't so bad, with the multimeter set to 200K I get a 150KΩ+ reading for just a moment, then open.

The lower element is all over the place. From the element to ground, it starts at 10KΩ and climbs over 200KΩ over several minutes. If I disconnect the probes and touch again it resumes from a little lower than where it left off. If you reverse the probes it starts again from ~10K and climbs. Almost behaving like a non-polar capacitor. What exactly is going on here...?
(Also - I have ran the heater with only the top element connected to the hot wires and it worked for an hour + without tripping the GFCI, until I turned it off. I was hoping the heat would dry it all out and resolve the problem. I tried the lower element alone and it trips the GFCI even after an hour of the top element less than 2" away baking.)

My question is: is it normal for an element to have a slight leakage to ground? I would have said anything but a non-continuous reading (infinity Ω) meant the element was shot. But I have 2 heaters here with 4 elements in total, and 3 of them have some reading to ground which strikes me as unlikely that 3 of the 4 are faulty. I have read the casing is a porous material and so with water around, a small leakage to ground is to be expected, and letting the element bake should resolve it. (But I don't know how true this is...)

The only way to get this to happen though would be to not use a GFCI which leads to my next question, should I not use a GFCI...? Again, I have read you shouldn't with saunas, but I would prefer one. Most of all I would prefer some clarification about what's going on with the elements...

Thanks in advance!
 
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Old 05-13-15, 10:36 PM
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I have a new sauna with two old heaters ??? What's up with that ?
Why not new heaters ?

Calrod type heater elements should have no continuity to ground. If it does.... it is bad.
In a sauna the water is supposed to get poured on heated rocks.... not the heating element. The heating element will split if it's red hot and water is poured in it.
 
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Old 05-14-15, 06:50 AM
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It is a sauna I have just built. A friend had a pile of cedar lying around for a decade or so and I offered, since they were never going to get around to it. The heaters came from someone else's renovation job some years back I wasn't the one who obtained them.

So any continuity to ground is a dead element? Is there any chance baking the element will improve it or should they just be thrown out?
 
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Old 05-14-15, 06:55 AM
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Elements

or should they just be thrown out?
Throw them out. Replace with new. Follow the new element instructions.
 
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Old 05-14-15, 06:24 PM
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Drying out the element fixed it

I ended up leaving the one working element connected and ran it for an hour or so last night then left the sauna closed for it all to cool slowly.

This morning I tested the bad element and it had no continuity to ground at all. So I wired it back up as it was originally configured and it works perfectly now. Both elements glow red and no GFCI tripping. The top element must have dried out the lower element over the hour.
 
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