The Masterplug MSTARCDKGMP RCD Safety Adaptor Plug simply plugs into the mains, then you plug your electrical appliance into it. If there is a fault or a short in the tool you are using, the unit cuts the power very quickly, reducing the risk of electrocution. The Masterplug Safety RCD Adapter continuously monitors the power supply to an electrical appliance and cuts off the power within 40 milliseconds if an earth current fault is detected. This is fast enough to prevent a fatal electric shock. The Masterplug RCD Safety Adaptor Plug is an ideal way to protect yourself when using portable electrical tools, like lawnmowers, hedge trimmers and mains powered drills. Electrical appliances can become dangerous if the wiring becomes loose, or their power cords become damaged or if they get wet. Not only power tools and lawnmowers can cause electrocution is also possible if fingers, wet hair or other conductive bodies enter the appliance. In all these cases the Masterplug Safety RCD is a must