What amperage fuses or circuit breaker do you need to fuse a kiln with? What size copper wire do you need?

The amperage rating of the fuse or circuit breaker needs to be 125% higher than the full load amps of the kiln. This is according to the National Electrical Code.

You then need to bump this calculated amount up to the next standard size fuse or circuit breaker.


  1. A kiln has a full load amp rating of 60 amps. 60 x 1.25 = 75 amps.  The next closest standard size breaker is an 80 amp breaker.
  2. A kiln has a full load amp rating of 48 amps. 48 x 1.25 = 60 amps. A 60 amp breaker is a standard size.
  3. The fuse amps are typically mentioned in the kiln electrical data located on the wiring diagram.

Always use copper wire to bring power to the kiln, NEVER use aluminum wire.  Near heat, aluminum oxidizes much more quickly than copper.

Wire sizes associated with the different size breakers.

20 amps
12 gauge copper
30 amps10 gauge copper
40 amps8 gauge copper
50 amps6 gauge copper
60 amps6 gauge copper
70 amps4 gauge copper
80 amps3 gauge copper
90 amps2 gauge copper
100 amps1 gauge copper
125 amps1/0 gauge copper (pronounced "one aught")
150 amps2/0 gauge copper (pronounced "two aught")
175 amps4/0 gauge copper (pronounced "three aught")
200 amps250 MCM copper wire (MCM = Thousand Circular Mils)
225 amps   
350 MCM copper wire