How does wire length affect the trip time of todays circuit breaker?
When the wiring shorts out, the longer the wire the longer it takes today’s circuit breaker to trip. The delay time between the occurrence of a short circuit (when the arcing and sparking begins) and the tripping of the breaker may vary from a few tenths of a second to several minutes, depending upon the available short circuit current. The variance in short circuit current is due to the type, size, and length of wire installed. In small homes the typical short circuit current, measured at the outlet, varies from 900 Amps down to less than 100 Amps (without extension cord). While in a larger home it may go as low as 30 Amps, at which level the trip time could exceed several minutes! Extension cords dramatically degrade the quality (reduce the short-circuit current) of existing outlets and extend the circuit breaker’s trip time. The longer it takes to trip the circuit breaker, when sparks start flying, the more likely that a fire will be started.
