Abstract: An arcing fault detector used the thermodynamic conditions created by an arcing fault within a vented electrical equipment enclosure to quickly activate a protective device which causes tripping of the supply circuit breaker(s). A plurality of temperature sensors are located within the enclosure near the top, and a differential pressure sensor is located in the external wall of the enclosure approximately midway between the vents to compare internal and external pressure. The intelligence from the sensors is processed by a fault protector which controls the tripping of the circuit breaker(s).