Preventing electrical hazards under grounding-fault condition by means of surface leakage protection

Appliance grounding, cooperating with over-current protection device, can prevent the appliance user from electric shock. But in the real world the appliance sometimes is not well-grounded. This paper proposes an innovative technology of "surface leakage protection" (SLP) which can be a good substitute of appliance grounding for electrical safety purpose. A SLP device detects electrical leakage at the surface of an appliance and removes the power supply immediately from appliance in case the leakage occurs, no appliance grounding is required. The principle of SLP is discussed, and the schematic diagram of the SLP is given with embodiment. The neutral line identification of SLP is also discussed to ensure a reliable SLP performance. The study and application embodiment indicate the SLP can effectively protect appliance user from electric shock in case of grounding-fault, and the building cost of a SLP device is similar to a Residual Current Device (RCD), easy to be widely employed.