Question 171Electricity & Electronics - Assistant Engineer

The correct answer is B) open the circuit breaker in the power supply and tag-out. This is the correct answer because before working on any electrical equipment, it is crucial to isolate the power source to prevent accidental energization, which could lead to serious injury. Opening the circuit breaker and tagging it out ensures that the power is disconnected and cannot be turned on while work is being performed. This is a standard safety practice required by electrical safety regulations and best practices. The other answer choices are incorrect because they do not properly isolate the power source. Heating the switch box, draining condensate, or spraying the gasket surface do not prevent the equipment from being energized, which is the primary safety concern when working on electrical systems.