Circuit Breaker Selection

Notes:

1. Circuit breakers are sized per article 427-4 of the N.E.C. The heater lengths shown above represent a current of no more than 80% of the breaker's rated size.
   

2. When using 240 volt product at 208, 220 or 277 volts, multiply the lengths shown above by the "length" adjustment factor shown in the Voltage Adjustment Table.
   

3. When using 2 or more heater cables of different wattage ratings in parallel on a single circuit breaker, divide 15 amps by the maximum footage shown in the 15A column above to arrive at an "amps per foot" figure for each cable. You can then calculate circuit breaker sizes for these combination loads. These "amps per foot" factors include the N.E.C. sizing factor in Article 427-4.
   

4. Article 427-22 of the N.E.C. requires ground-fault equipment protection for each branch circuit supplying electric heating equipment. Exceptions to this requirement can be found in the 1996 N.E.C.