How to calculate the heat generated by a molded case circuit breaker. Watt loss per pole.
The amount of heat a circuit breaker generates per pole (watts loss) can be calculated with the following formula: P=I^2 x R
- P = Watts loss per pole, in Watts
- I = current in Amperes
- R = pole resistance in Ohms
The pole resistance (in micro Ohms) for most circuit breakers can be found in the Field Testing and Maintenance Guide 0600IB1201,
pages 17, 24 and 34.
: From page 17, the pole resistance for a Powerpact H frame 15 amp breaker is 35,000 micro Ohms. Convert that to .035 Ohms.
Now using P=I^2 x R, P = (15 amps) x (15 amps) x (.035 Ohms) = 7.9 Watts per pole
This breaker generates or loses 7.9 Watts per pole. For a 3 pole breaker 7.9 Watt x 3 poles = 23.6 Watts