Power Question For New Kiln

[Jon W]

I recently ordered this kiln: http://www.bigceramicstore.com/cress-bt711h-kiln.html, thinking I could upgrade the breaker from 15 to 20 amp (outside GFCI outlet on a covered porch), only to find out the wiring to the outlet is 14 gauge and would need to be 12 to handle 20 amps. They recommend 20 amps for this kiln but it doesn't say it's required. I also have a Paragon Fusion 7 Glass kiln and have used this outlet going to max temp. (1700 deg.) for pot melts many times with no problems. I usually fire my glass overnight with nothing else running and would do the same with ceramics in the Cress. Am I going to have a problem tripping the 15 amp breaker? The cost of upgrading the wiring to handle a 20 amp breaker has me worried.

Thanks 

[Jon W]

BTW, I just checked specs. and both kilns are 1800 watts.

[Mark C.]

Jon,

This kiln draws 15 amps according to specs

You are supposed to have a 20% extra safety factor in the line/breaker-you do not have any extra-even the outlet I bet is a 15 amp one.

In my world the #14 wire is used for lighting circuits -we do not use it for outlets but thats California .

I would worry about fire on overheated wire as you are at the maximum load for said wire.

How about being worry free and rewiring with #12 wire on a 20 amp breakers as the specs say is best on your link you provided.The outlet itself also needs to be a 20 amp outlet as well.

That outlet is only good for toaster and maybe an occasional hair dryer or some Christmas lights

Always better with kilns to be safe than sorry. They are large amp draws and that outlet is just plane underrated .

Hers the deal that kiln on high will draw all the rated amps it can get-so thats called LOAD-that load is what heats up and loose connections or underrated wire or breakers. depending on the breakers to not start a fire is just a bad idea.

Even with the 20%  over rated I personally have cooked my secondary panel at the connections over the decades.

 

my 2 cents

[Denice]

My electrician did my wiring for my test kiln exactly like Mark described.  I use to e-mail back and forth with a potter that did the same thing you are talking about.  He nearly burned down his house, it was a older house he had to fix interior and structural damage, replace the wiring and plumbing and bring it up to current codes.   Denice

[Marcia Selsor]

20 amps is really best. I have a little test kiln and had wiring installed in Montana on my back porch. Worked fine. In Texas I plugged it into a car port outlet. not fine. outlet melted a little around the edges. By the time my kiln shed was built and I moved it in there with the bigger kilns, everything was fine ago. 

As mark said 20% higher breaker. 

Marcia

[glazenerd]

Once you pass 50 linear feet of wire, resistance begins to cause a drop in voltage. So you need to check the total length of this run of wire. I am guilty of over- kill, but there is a method to my madness. I have a small kiln as well, to which I ran a 10-3 wire. 1. It carries the load with no voltage drop. 2. I have a second power feed if I ever upgrade. 3. If I move a piece of equipment that requires more power, I do not have to re- wire. 4. Most of the outlets in my studio are ran in 10-2 wire, so I am not limited in where I can put things.

 

In your case, you are talking no more than $40 to run it in a 10-3 wire. Then you have safety and flexibility in the future. Again however, most would view it as over- kill.

 

Nerd

[Guest]

When in doubt build stout

[Mark C.]

I have too have been called a classic overbuilder but in this case #12 wire is the minimum for your kiln.

[Dick White]

For those interested in the purpose of the 20% overrating requirement - The wire size specs in the code are designed around the notion that in ordinary usage, a particular circuit is on at maximum amperage intermittently for only short periods of time - the time needed to make the toast or dry your hair. The proper wiring will get a little warmer, but if installed correctly (in an adequate airspace) it will cool off again very soon. So, no problem. However, any circuit that is expected to service its maximum allowable load for an extended period (a kiln, an oven, even commercial lighting circuits that are fully loaded and on all day long) must be overrated by 20% to minimize heat build-up.  So, yes, if you do the math you theoretically can push 1800 watts through a 15A circuit, but for practical purposes you can only do that for short periods of time without the danger of igniting the wires inside the wall. No problem with the hair dryer. Big problem with the kiln.

[Jon W]

Thanks all. Yes, I talked to a friend this morning who's an electrician and he's helping me run a separate line and outlet. The last thing I need is a fire. I'm screening in the covered porch and will probably get some tarps that I can roll down in bad weather to keep it out. I have a BBQ grill cover over my glass kiln and will do the same with the Cress. Thanks again for all the answers, I really appreciate it.

[Mark C.]

Thanks all. Yes, I talked to a friend this morning who's an electrician and he's helping me run a separate line and outlet. The last thing I need is a fire. I'm screening in the covered porch and will probably get some tarps that I can roll down in bad weather to keep it out. I have a BBQ grill cover over my glass kiln and will do the same with the Cress. Thanks again for all the answers, I really appreciate it.

Great move toward doing it right-consider running larger wire for future service.