Unbelievable, simply unbelievable

It must be very expensive to consult with an electrician, or hire a licensed electrician to have on your staff. I’ve just spent several hours going through the websites of the major kiln manufacturers: Paragon, Skutt, Jen Ken and AIM. Everyone one of these kiln manufacturers is in violation of the US NEC (National Electrical Code) on at least one of their kilns.

Let’s take Paragon as an example. Of their line of approximately 46 electric kilns, only 10 had the proper plug on the kiln power cord as well as the proper recommended circuit breaker for the kiln. Several of their kilns draw 20 amps, and Paragon uses a 20 amp plug and recommends a 20 amp circuit breaker!

No wonder people have problems using their kilns.

I can’t help but wonder if anyone at any of these kiln manufacturers even has a copy of the current NEC code, much less consults it on a regular basis.

I can certainly understand the design philosophy (although I totally disagree with it!) that they (the kiln builder) wants to have a kiln that will plug into an ordinary outlet (rated at 15 amps). But what I don’t understand is why they can’t simply build the kiln so that it draws a maximum of 12 amps.

There is no excuse for putting their customers at risk by providing equipment that does not meet the National Electrical Code.

More on amperage ratings for kilns

I’ve received some feedback from folks wanting more information about my previous post “The rule of 80% and kilns“.

First, here is a direct link to the NEC (National Electrical Code): http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70 (scroll to near the bottom of the page and click on the link that says “View the 2008 edition of this document”)

The important sections are 210.21 and 210.23. In part, they say:

Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle

Circuit Rating …………………… Receptacle Rating ………………. Max Load (Amperage)
15 or 20 Amps ………………………. 15 Amps ……………………………… 12 Amps
20 Amps ………………………………. 20 Amps ……………………………… 16 Amps

210.23 Permissible Loads

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place

The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit amperage rating.

Kiln power cord too short?

DON’T use an extension cord, ever.

There’s a reason that power cords on kilns are short, and that’s because they use large amounts of energy, usually 13-14 amps at a minimum.

Adding an extension cord adds two additional sets of contacts, not to mention the possibility of a smaller wire diameter.

One well-known kiln retailer (who happens to live and work in Canada) even states

You can run house wiring 100 ft from the service panel so there’s no reason you can’t use a 100 ft extension cord.

Kiln controllers — everything you didn’t want to know

There are three basic types of temperature controllers available: ON-OFF, Proportional and PID.