Which colour plug indicates a 400 volt supply on the site electrical distribution system?

The reason the red plug indicates a 400-volt supply on the site electrical distribution system is rooted in the standard color coding used in electrical installations. The use of red plugs signifies three-phase electrical supply systems, which typically operate at 400 volts in many regions. This color coding is crucial for ensuring safety and reliability in electrical systems, as it provides a clear visual indication to workers about the voltage and type of supply they are working with.

In contrast, blue plugs are typically associated with 230-volt supplies and single-phase connections. Yellow plugs can represent different circuits depending on the context, while green is often reserved for earth connections. The standardization of these colors helps prevent accidents and confusion on job sites by enabling workers to quickly identify the specific voltage and type of electrical supply they are handling.