There are two basic parts of a kiln: the firing chamber and the switch box. (If your kiln doesn’t have a switch box, it is probably because the electrical parts are kept inside the enclosed base of the kiln. An example is the Paragon SC-2 silver clay kiln.)
When you need to remove the switch box, such as when you change elements, it is a good idea to perform the following maintenance steps. I would also do this after purchasing an older used kiln.
However, these maintenance steps are usually unnecessary for the small tabletop kilns such as the SC-2. The small jewelry kilns operate on only 120 volts, fire to relatively low temperatures, and are usually subjected to less dust than the larger studio kilns.
SWITCH BOX MAINTENANCE
1) Always disconnect the power. Then remove the switch box following the instructions in your kiln manual. If your switch box has a Kiln Sitter, pull straight out to avoid damaging the Kiln Sitter tube.
2) Unless your switch box is hinged, find something to prop it up so that it doesn’t pull against the element wires. Position the switch box so that you can see inside it easily.
3) Dust can cause parts to overheat, because dust acts as an insulator. After changing the elements or thermocouple, blow dust out of the switch box using canned air. (It is available from computer or camera stores or even Wal-Mart.) Wear a facemask. Do not hold the canned air upside down, and never spray yourself. (The air gets cold enough to cause injury.) Hold the air nozzle 6” away from the parts you are spraying.
You could also use a vacuum cleaner and a dry paintbrush to clean the switch box of switch-operated kilns. But I do not recommend them for cleaning digital kilns. They can create a static charge that could damage the electronic controller.
4) Examine the wires. Use a flashlight if lighting around the kiln is dim. After decades of heat, the insulation on wires becomes brittle. Signs of aging insulation are white wires that are brownish and colored wires that are fading. When you bend wires, do you hear or feel the insulation cracking? 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 use electrical tape to repair wiring inside a kiln switch box. When I first started working at Paragon, electrical tape was not even allowed inside the building.
5) After cleaning the switch box and checking the wires for heat damage, then check the wire terminals for tightness. If terminals seem corroded, but everything is working, I would not clean the terminals. I would leave well enough alone. (On the other hand, if a switch has stopped working, sometimes just cleaning the terminals can get it working again.)
Last week I wrote, “Frequently plugging and unplugging heavy-amperage cords will weaken the wall outlet.” A reader asked, “Should you leave the kiln plugged in all the time?”
No. You should disconnect the power when the kiln is not in use. For large studio kilns, I recommend an electrical shutoff box in addition to a circuit breaker at the electrical panel.
The shutoff box should be positioned on the wall near the kiln, between the kiln and the door to the firing room. The shutoff box disconnects the power without having to unplug the kiln.
Here in Mesquite, the morning was cool for the first time this fall. I hope you are enjoying the change of weather.
With best wishes,
Arnold Howard Paragon Industries, L.P. - Better Designed Kilns 2011 South Town East Blvd. Mesquite, TX 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 firstname.lastname@example.org / www.paragonweb.com