What is a critical action to take before plugging in or unplugging studio lights?

Turning off the circuit breaker before plugging in or unplugging studio lights is crucial for safety reasons. This action prevents electrical shock and reduces the risk of short circuits or other electrical hazards that could occur if the lights are connected to power while being manipulated. Working with studio lights can involve high voltages, and without ensuring the power is off, there's a significant danger to both the equipment and the individuals handling it.

Checking the light's temperature and ensuring the lights are on are actions related to the operation of the lights but do not address the safety measures necessary before handling the equipment. Adjusting the light’s angle is a part of lighting setup but does not pertain to the safety precautions that should be taken when plugging in or unplugging the lights. Therefore, turning off the circuit breaker is the most critical and safe practice in this context.