Where should the electricity be turned off before commencing work in a room?

Turning off electricity in the main electrical box is the safest and most effective approach before starting work in a room. This action ensures that power is completely shut off to the entire electrical system in the area you will be working in, reducing the risk of electrocution and making it safer for workers to handle electrical components.

The main electrical box, also known as the service panel, typically controls all circuits in a building, allowing for a comprehensive shutdown rather than just isolating specific circuits or outlets. This precaution is essential for ensuring that no unexpected power is present and that workers can focus on their tasks without concern for live electrical hazards.

Other options, which involve turning off electricity at temporary circuit breakers or individual outlets, could leave some circuits still energized, increasing the risk of accidents. Additionally, turning off electricity at a distant location like a power plant is impractical and unfeasible for providing immediate safety in the workspace. Therefore, isolating power at the main electrical box is the most reliable method to ensure safety when performing electrical work.