Wire connections must be tight inside the kiln switch box.
Aging Kiln Switch Box Wires
Recent Q&As: Fear of kilns; excessive drop in temperature during a hold
AGING KILN SWITCH BOX WIRES
Poor electrical connections can cause intermittent kiln problems. One firing is perfect, and the next firing is slow for no apparent reason. Then the kiln fires normally again.
Sometimes brittle, very old wires cause intermittent problems. Someone wrote, “I have been fighting relay problems. The kiln will work one or two times. Then out goes the bottom set of elements from the relay frying.”
I suggested, “Check the wires that connect the relay. If the push-on connectors on the ends of the wires are damaged, the new relay will fail, too. A loose push-on connector can overheat, which can destroy the new relay in just a few firings.”
The kiln owner wrote back, “We did finally track it down to the wiring to the relays. The wires were worn and brittle. So we replaced them and I’m back in action.”
Whenever you open the kiln’s switch box for routine maintenance, examine the wires and connections. Make sure everything is tight. In older kilns, look for discolored and brittle wire insulation. Do the wires in an older kiln make a cracking noise as you bend them? When insulation cracks off the wires, it is also likely that strands of wire are breaking, too, which can raise the resistance and cause the wires to overheat. Replace damaged wires. Make sure the terminals are tight when installing new wires. Do not repair insulation with electrical tape.
Q. You know what? I'm still a little scared of my kiln. Is that normal?
A. Yes, it is normal to be afraid of the kiln until you have gained experience. But it won't be long before you feel confident enough to offer advice to beginners. Firing a kiln is like riding a bicycle--the beginning feels awkward, but that is quickly forgotten with experience.
Q. My controller temperature goes down 20 to 30 degrees during a hold before the kiln turns back on. What is causing this?
A. The relay in your kiln is waiting too long to send power to the elements. Please make sure the wires that are attached to the relays are tight. The temperature drop may be due to a loose controller-to-relay wire.
Q. Pinging or popping noises are coming from my kiln as it cools. Is that normal?
A. Faint popping noises are the sound of the firebricks and the metal jacket cooling down and shrinking. Yes, this is normal. It is similar to the sound of a muffler as it cools after you have parked a car.
Popping noises from inside the kiln, however, may indicate that ceramic ware is exploding because of trapped steam inside the clay. It will sound like popcorn. This is why the ware should be bone-dry before firing the kiln. If you hear popping from inside the kiln, do not open the kiln until it has cooled to room temperature.
“Making art is like breathing for me.” --Jeannette Froese LeBlanc
Two weeks ago I attended the Glass Art Society Conference in Seattle, Washington. The Paragon booth was between CBS Dichroic and Bullseye Glass, so I was surrounded by glittering color. A huge video screen 50 yards away showed close-ups of live flame-work demonstrations.
At the show I talked to David Keens, who teaches glass at UT Arlington. He told me he happened to displayed a 30” tall glass sculpture of a tornado in Mobile, Alabama—just before a real tornado hit.
In the last Kiln Pointer, I wrote about a storm that swept through Mesquite. “Rapid flashes of lightning revealed a distinct wall of blackness that looked like the edge of a bulging tornado--but it wasn’t.” Later an insurance adjuster told me that the black, sharp-edged funnel actually was a tornado! We were fortunate that it didn’t touch down in Mesquite.
With best wishes,
Arnold Howard Paragon Industries, L.P. – Better Designed Kilns 2011 South Town East Blvd., Mesquite, Texas 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 / firstname.lastname@example.org / www.paragonweb.com / www.facebook.com/paragonkilns
Copyright 2011, by Paragon Industries, L.P.