KNOWLEDGEBASE

KNOWLEDGEBASE

Switching manual kiln (50 amps) from 208 volts to 240 volts

All the elements will need to be replaced. For example, the ohms on the J230 208-volt element circuits should be around 14.2. If you put 240 volts to each circuit it will pull around 17 amps per circuit- which is too much. The infinite switch used in manual L&L kilns can only handle 15 amps. Some older J models, DaVincis, Ovals, B, SQ, and G models were made with 208-volt infinite switches. It has been proven that 240-volt infinite switches work fine at 208 volts, but it has never been determined if 208-volt switches work fine at 240 volts. L&L's official recommendation is to replace 208-volt infinite switches with 240-volt switches when switching to 240 volts. When switching to 208 volts from 240 volts a switch change is not necessary. Changing voltage sometimes means pulling more amperage. Be sure to check the electrical specs for your kiln as it will be after the change- i.e. if you are changing to 240 volts look for the electrical specs in 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 amps 10 gauge copper
40 amps 8 gauge copper
50 amps 6 gauge copper
60 amps 6 gauge copper
70 amps 4 gauge copper
80 amps 3 gauge copper
90 amps 2 gauge copper
100 amps 1 gauge copper
125 amps 1/0 gauge copper (pronounced "one aught")
150 amps 2/0 gauge copper (pronounced "two aught")
175 amps 4/0 gauge copper (pronounced "three aught")
200 amps 250 MCM copper wire (MCM = Thousand Circular Mils)
225 amps    350 MCM copper wire