I am switching my computerized L&L kiln from 208 volts to 240 volts. What do I need to do to the kiln?

  1. All the elements will need to be replaced.  Why?  For example, the ohms on the JD2927 208 volt element circuits should be around 10.4. If you put 240 volts to each circuit it will pull around 23 amps per circuit- which is too much. There should not be more than 20 amps per circuit for the JD2927 208v kiln.
  2. Computerized controls will run fine on 208 or 240 volts.
  3. Changing voltage sometimes means pulling more amperage. Be sure to check the electrical specs for your kiln as it will be after the change.  For example, if you are changing to 240 volts look for the electrical specs your kiln as a 240 volt kiln. Be sure your breaker and wire size are large enough. Breaker size is determined by the new amp rating of the kiln, multiplied by 1.25 (125%) and then rounded up to the nearest breaker size. Wire size is tied to the breaker size:
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