Adding a fuse or circuit breaker to the __________ of a parallel circuit will help protect the components from damage.

• A. Branch line
• B. Main line
• C. Load side
• D. Neutral conductor

Answer: (B)

The protection feature should be placed on the main line because it sits upstream of all the parallel branches. When a fault or overload occurs anywhere in the circuit, the fault current is drawn through that main line. A fuse or circuit breaker there will sense the overcurrent and interrupt power to the entire parallel network, preventing damage to wires, components, and downstream equipment and reducing fire risk.

If protection were only on a branch line, that branch would be isolated, but the other branches could still be exposed to excessive current or could remain energized despite a fault elsewhere. If protection were on the load side, the faults originating upstream could still push high current into the circuit and potentially damage upstream parts. Fusing the neutral conductor isn’t standard protection practice because it doesn’t reliably interrupt fault currents on the hot conductor and can create safety hazards.