Industrial and multiphase plugs and sockets provide a connection to the electrical mains rated at higher voltages and currents than household plugs and sockets. They are generally used in polyphase systems, with high currents, or when protection from environmental hazards is required. Industrial outlets may have weatherproof covers, waterproofing sleeves, or may be interlocked with a switch to prevent accidental disconnection of an energized plug. Some types of connectors are approved for hazardous areas such as coal mines or petrochemical plants, where flammable gas may be present.
Plugs and sockets are provided with on-load switch and for safety reason the plugging is possible only with an open on-load switch. They can be made of Polyamide and Fiberglass Reinforced Polyester. The materials used have proved to be safe and reliable for both indoor and outdoor installations, in particular in chemical and off-shore plants or hazardous area.