48A kiln wiring requirements?
Sorry for the cross post, but I realized that just because the question is electrical doesn’t make it “energy” (as in heating and HVAC). I don’t see any way to change my post’s discussion category.
When we upgraded our electrical wiring last year, we included 240V wiring to the garage for future installation of an electric kiln. Now we are looking at different kilns, and trying to select a kiln that will be large enough but still safe with the wiring that we got.
We have a 4ga feeder from the main panel to a subpanel in the garage, on a 60A breaker. The garage subpanel has a 20A breaker for the lights and general use receptacles, and a 50A breaker for a dedicated 240V circuit for the kiln. The kiln receptacle is only about 12-18″ from the subpanel. I assume the wire for that is 6ga, although I don’t know for sure. (I know about the feeder because the electrician told me the wire was good for 70A even though the breaker is 60A). The kiln receptacle is 6-50, which is what most of the kilns we were looking at a year ago specify.
So here’s the question. Many of the size kilns we are looking at say they draw 11.5kW and 48A. One brand of kiln specifies 4ga wire and a 50A breaker, and another specifies 6ga wire and a 60A breaker. What could account for the difference, if they both draw 48A?
This is not a motor, so I wouldn’t think there would be a huge induction draw on startup. There could be some variability in the draw depending on where you are in the firing cycle, but why a larger breaker with a smaller wire? The ampacity table I’m looking at gives 55A as the 60 degC (140 degF) rating for 6ga wire.
The ambient temperature will be increased some due to proximity to the kiln, but I don’t know by how much. This effect can be limited by placing the kiln as far away from the receptacle as the cord will permit and leaving the garage door open when firing (probably a good idea anyway for ventilation). Does the short length of the wire make any difference?
BTW, I assume they’re talking about the branch circuit when they specify the wiring size, but could they talking about a field-wired cord for the kiln itself???
Please enlighten me.
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someone's attention that can help you with advice.
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Thanks for the bump, but I've gotten several good replies in my original posting location, so all is good.Rebeccah