Thermal magnetic circuit breakers are especially well suited for overload protection of conductors when circuit breakers are exposed to similar ambient temperatures because the circuit breaker continuous current rating changes in about the same ratio as the average conductor rating changes with the ambient temperatures. The magnetic trip portion of the circuit breaker offers short circuit protection.

Ambient compensating circuit breakers provide overload and short circuit protection but has temperature compensating elements which counteract the effect of ambient temperature changes thereby maintaining the calibrated current setting throughout a temperature range. Typical applications are a circuit breaker located outside and protecting wire in a temperature controlled building; circuit breaker is exposed to changing temperature conditions and is protecting underground cable; overload protection of conductors are not of prime importance or protection of a portable generator designed to operate throughout varied temperature extremes.

Magnetic circuit breakers are available in the same operating characteristics as ambient compensating. The intended use is the same as in 6.1.1.1 and 6.1.1.2.

Fused circuit breakers incorporate fuses or current limiters in series with the circuit breaker elements to increase the interrupting capacity of a circuit breaker.