What causes arcing in electrical circuits?
Arcing is due to electrical current jumping across an air gap producing heat and a visual light. Low current arcing does not always contain sparks. Some appliances contain acceptable arcing; e.g., the electric drill produces arcs when the electrical contact brushes move from commutator section to commutator section. This type arcing is not hazardous. Wiring arcing above 5 amps can produce sufficient heat and sparks to start a fire. Today’s circuit breaker can only respond to arcing above its rating, i.e. a 20 amp breaker ignores arcing below 20 amps. Today’s circuit breaker treats arcing above 20 amps as overload current. But, the circuit breaker has been designed to be slow in its response to intermediate overloads. Further, today’s circuit breaker technology (thermal bi-metallic strips & magnetic aids) does not permit a faster response without increasing nuisance tripping to an unacceptable level. Sparks are the molten metal which is thrown off and have the appearance of a arc welder
