Why does the kiln's breaker keep tripping?

strict warning: Only variables should be passed by reference in /home/hotkilns/public_html/sites/all/modules/captcha/captcha.inc on line 61.

Search Knowledgebase

Knowledgebase FAQ

  • See the Sales FAQs for Frequently Asked Sales and Preorder Questions
  • The Knowledgebase is organized into a series of questions and answers having to do mostly with technical troubleshooting and understanding of kilns.
  • Although we write this for our own kilns many of these articles apply to other makes - although L&L takes no responsibility for that.
  • Many Knowledgebase articles have Actions, PDFs and Videos associated with them.
  • Actions are specific actions for you to take during the troubleshooting or repair process.
  • Each Action may also have Videos and PDFs associated with it and, in addition, specific Cautions.
Why does the kiln's breaker keep tripping?
  1. Breakers can trip on the kiln for a couple different reasons. What is important to know is, when does it trip?

  2. Does it trip as soon as you turn the toggle switch on?
  3. Does it trip as soon as the relays engage?
  4. Does it trip after the kiln has been on for a while?
  5. Another important thing to know is what happens when the breaker is reset.
  6. Does it not let you reset it at all?
  7. Does it immediately trip again as soon as you re-start the program?
  8. Does it wait a while, like 20 minutes, and then trip again?

  9. Does it trip as soon as you turn the toggle switch on? This means there is a short to ground in the control circuit.
  10. Does it trip as soon as the relays engage? This means the short to ground is somewhere after the relays. Often it can be where the element wire passes through the wall of the kiln. On older kilns there are ceramic bushings on the outside of the hole the element wire passes through to keep the element from touching the stainless steel kiln case. They can come off allowing the element to touch the stainless case.
  11. Does it trip after the kiln has been on for a while? This means there is poor connection between the power wires and the breaker (check the tightness of the wires at the breaker) OR it means the wrong size wire was used, OR it means that the breaker itself is worn out or just no good. There is NEVER a problem with the kiln when the breaker just trips after being on for a while, and when you reset it the kiln can come back on.
  12. Does breaker not let you reset it at all, even when the kiln is completely off? This means there is a short to ground somewhere between the breaker and the line side of the relays OR maybe in the first part of the control circuit.
  13. Does it immediately trip again as soon as you re-start the program? This means there is a short to ground somewhere after the relays, like where the ceramic bushing may have fallen out.
  14. Does it wait a while, like 20 minutes, and then trip again? This means for sure that there is either a poor connection between the wires and breaker OR the wrong size wire used, OR a bad breaker.
  15. To find a short, use the multimeter's continuity tester with the power OFF. When you read from Hot to Ground there should be no continuity. In a circuit where there is a short you will get continuity from Hot to Ground. Isolate parts of the circuit and see if there is still continuity from Hot to Ground. Keep isolating a smaller and smaller area in the circuit until you find where the short is.

Additional Actions to Take

  1. Make sure the circuit breaker or fused disconnect switch is turned on.
  2. If you have a circuit breaker flip it back and forth to make sure that it is really on. Some circuit breakers, if they have tripped, will not be obviously in a tripped position. By flipping it back and forth you will reset the circuit breaker.
  3. Check voltage of your power supply at the receptacle using your multi-meter set to the next highest AC voltage above 240 (typically this will be 600 volts but may be 250)
  4. Check fuses for voltage continuity. You can do this with your multi-meter.
  5. Make sure fuses or circuit breaker are/is the proper amperage and type. See your wiring diagram for the required fuse type.

CAUTION: This test should only be done by an experienced person familiar with electricity.

  1. The control fuse is normally located on the side of the control box.
  2. Twist open the fuse holder and physically check the little fuse.
  3. If the fuse is blown then you will see the metal element inside is melted.
  4. Optionally, you can use your digital multi-meter to check continuity across the fuse.
  1. Check the tightness of all connections. Do this by wiggling the connector to make sure it is not loose.
  2. Examine all connections for any sign of oxidation or discoloration.
  3. Examine all wires for signs that the wire may have burned.
  4. Make sure all wires are connected to their proper connection point. You may have to compare the kiln to the wiring diagram to be sure of this. This step would be particularly important if a wire has come loose.
  5. Look for any place where a wire may have shorted against the metal case or a component.

CAUTION: Turn power off to kiln form the circuit breaker or unplug the kiln.

  1. Unplug kiln.
  2. Trace wiring for missing or bad connections.
  3. Check wiring against wiring diagram.
  4. Check for corroded connectors or connectors that have frayed wires. Replace any such connectors.