Testing Kiln Elements
by Lou and Joan Benzell
Kiln performance is dependent on the integrity of the heating elements. All too often we forget that they do wear out, and when they do, we don't know which one has gone bad or which one is going bad. When your kiln starts to take longer with each firing to bring the fired pieces to maturity and you notice that your electric bill looks like the national debt....check your elements. These are the curly wires lodged within the fire brick on the inside of your kiln.
The simplest way to do this is to buy a decent quality ohm digital meter or borrow one if you know someone who dabbles in electricity. Call your respective manufacturer of the kiln you use and give them your kiln model number. Ask the manufacturer for the ohm specification for the elements in your kiln. Ohms measure resistance...the more resistance your elements have, the less heat your kiln will produce.
Safety Note: Do not turn the kiln on for this procedure and pull the plug from its wall receptacle.
Using my kiln as an example, the top element has a resistance of 12.2 ohms when new and a resistance of 6.1 ohms when new on each of the two elements coming off the bottom switch. We have three separate elements (one for the upper switch and two for the bottom switch). With the kiln turned off and unplugged, place the meter probes at each end of each element (all from the same switch) at the location where it goes into the wall of the fire brick. Follow the same procedure with each of the elements in your kiln. With our kilns, if the ohm reading or resistance goes above 7.2 (upper) or 14.4 (lower two) I know that the element(s) is/are bad and needs replacing.
This may seem awkward if you lack experience with electricity but the testing procedure is simple and it will give you a clue as to why your kiln isn't firing properly or more specifically, if its going to fail on you. Most manufacturers will be glad to help you. It is also very helpful when the electrician or service man (if you use one) know these specifications.
Murphy's Law is always at hand when you are under pressure to fire large loads with completion dates and you find your kiln functioning improperly. Replacing your elements is an easy fix to insure problem free firings.....and remember, don't fire anything that you don't know where it was, or where it came from.
What a difference a new element makes...both in performance and on my check to the electric company.