Hello Candidate,

The Breaking capacity of any electrical component of a circuit refers to the safe zone or the maximum limit upon which that particular electrical instrument can be here the load of its voltage or current.

In the Given questions its mentioned that there is a 12 KV circuit breaker which means that the voltage provided is equal to 12000 volts and 600 ampere current is flowing through the circuit. So, the maximum safe limit of resistor which can be attached to the circuit is equal to 20 ohms.

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