How can my kiln section stay on all the time in my computerized kiln, even when the on/off switch is off?

A Relay May Be Stuck Shut

  1. All computerized kilns use relays to cycle the power on and off to the kiln sections.
  2. If one of those relays sticks shut, power will go to the kiln all the time.
  3. All L&L Kilns relays and contactors are of a type called "normally open", meaning when there is no power coming to their electromagnetic coil their electric contacts are open and not allowing power through.
  4. If a relay overheats, its contacts can weld themselves shut causing power to pass through them even when the kiln is off.

How to Tell For Sure

  1. When the kiln is cold, keep the toggle switch off and plug in the kiln.
  2. Can you hear the electricity humming in the elements?
  3. Wait a minute, can you feel the heat from any of the elements? If so, which ones? (be careful not to actually touch them).
  4. Whichever elements come on, replace that section's relay.