Which circuit breaker will blow first

circuit-protection

Assume that Each circuit breaker is identical.

Each breaker trips at 15 amps on a 120V circuit.

One circuit breaker is located back at the circuit box with 50 feet of wire to the outlet.

The other circuit breaker is located at the outlet with 5 feet of wire to a high load application which draws more than 15 amps.

Which circuit breaker has a higher chance of blowing?

I would imagine the one at the box because more current may exist due to the resistance in the 50 feet of wire.

Best Answer

If all the breakers are absolutely identical, then they will both trip at the same instant.

The current flowing through them both will be the exact same amount of current.

schematic

simulate this circuit – Schematic created using CircuitLab

With no branches in the circuit, just a simple ring, the current at all points will be the same - simple KCL. AM1 == AM2.

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