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I have two circuits in my garage. One is a 15amp circuit that powers the garage door and has two outlets, the other is a dedicated 20amp fridge outlet. Both have GFCIs. I'm trying to run a kiln in the garage and it keeps tripping the GFCI. What's weird is that it keeps doing different things.

For context, the machine needs to be run for 14+ hours straight overnight when in use. I was able to achieve this cycle once, but the next time I tried it tripped the GFCI sometime in the night. After then, the kiln would trip the GFCI almost instantly when the kiln's heating element was turned on. The kiln seemed to be fine when turned on but not actively heating.

A couple days later I tried it again, and after 2 hours or so of heating, the GFCI had not tripped. Thinking the issue had somehow resolved itself, I did another night cycle only to find it had tripped sometime during the night. I am almost certain the furnace does not trip on normal circuits.

Relocating the kiln is out of the question. Obviously I can't have a kiln inside my home and the outside outlets all have GFCI as well.

I really wish to get this kiln working again soon so I've been debating bypassing or installing a regular outlet, although doing so does scare me a little bit. I'm just not sure what the issue can be here.

isherwood
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Jimbo1991919
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2 Answers2

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  1. You have an actual ground fault. Think this first when a GFCI trips, it's usually the answer. Because kilns operate over a very wide temperature range, there's considerable potential for things to move so you can quite easily have an intermittent ground fault due to heat causing things to touch. If properly designed, built and maintained that should not happen, but it can happen. Usually that means maintenance is required. Also, a kiln kept in a damp area may have issues due to moisture in the firebrick insulation.
  2. One of the various issues with GFCIs mentioned in comments - particular ones tripping on heavy loads, or due to old age, or some other cause that's not an actual ground fault. If you try new/different GFCIs and the problem persists, see item 1.
Ecnerwal
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Resistance of the heating coils or elements in a kiln changes with the temperature of the kiln (and also as the elements age). If the kiln is fine when it's cold and shutting off when it's hot, that might help explain what's going on. Or if you've moved the kiln recently, it may also be a loose connection within the kiln that only shows up when it's hot. You could try running it up to temperature, empty, while you can watch it, to test for this.

Charles B
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