The PowerPact™ H-frame circuit breakers are designed to protect electrical systems from damage caused by overloads and short circuits. H-frame and J-frame circuit breakers are available with either thermal magnetic or Micrologic™ electronic trip units. L-frame circuit breakers are available with Micrologic™ electronic trip units only. H-frame and J-frame circuit breakers with thermal magnetic trip units contain individual thermal (overload) and instantaneous (short circuit) sensing elements in each pole. The amperage ratings of the thermal trip elements are calibrated at 104 deg F free air ambient temperature. Per the NEC and the CEC, standard circuit breakers may only be applied continuously at up to 80% of their rating. Circuit breakers rated for 100% operation are available but require specially designed enclosures and 194 deg F rated wire.