Industrial Plug 5 Pin 16AIndustrial plugs and sockets are used in the outdoor construction sites in which the wire connections are exposed to bad weather or damp ground. Also used in the places where the wiring connections are exposed to water. The cable connectors and sockets are keyed and colour coded, according to the voltage range and frequency used; common colours for 5060 Hz AC power are yellow for 100130 volts, blue for 200250 volts, and red for 380480 volts.