When may a circuit remain energized with the master switch open? When the circuit

When may a circuit remain energized with the master switch open? When the circuit

• A. supplies power to emergency equipment
• B. is an intermittent load of not more than 6 amps
• C. is rated at 5 amps or less and a circuit protective device is adjacent to the power source
• D. None of the above

Answer: (C)

The idea being tested is that the master switch doesn’t completely disconnect every possible circuit. A very small circuit can remain energized even with the master switch open if it meets two conditions: it draws only a small amount of current (5 amps or less) and there is a circuit-protective device located right at the power source. In this arrangement, the protective device provides isolation and protection for that small circuit without depending on the master switch to interrupt its feed. That limits potential hazards while allowing limited continuous power to a tiny load. Why this fits the best: the 5-amp limit ensures the circuit isn’t capable of powering larger loads that would present greater risk during maintenance, and having the protective device adjacent to the power source means the small circuit can be isolated from the rest of the system even when the master switch is open. The other options describe scenarios that either imply a larger or more critical load staying energized or rely on conditions not supported by the regulation.

The idea being tested is that the master switch doesn’t completely disconnect every possible circuit. A very small circuit can remain energized even with the master switch open if it meets two conditions: it draws only a small amount of current (5 amps or less) and there is a circuit-protective device located right at the power source. In this arrangement, the protective device provides isolation and protection for that small circuit without depending on the master switch to interrupt its feed. That limits potential hazards while allowing limited continuous power to a tiny load.

Why this fits the best: the 5-amp limit ensures the circuit isn’t capable of powering larger loads that would present greater risk during maintenance, and having the protective device adjacent to the power source means the small circuit can be isolated from the rest of the system even when the master switch is open. The other options describe scenarios that either imply a larger or more critical load staying energized or rely on conditions not supported by the regulation.