A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a device to quickly disconnect current to prevent serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a person falls after receiving a shock. In the United States and Canada, the device is more commonly known as aground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or an appliance leakage current interrupter (ALCI). In the United Kingdom, these are better known by their initials RCD, and a combined RCD+MCB is known as a RCBO (residual-current circuit breaker with over current protection). In Australia, they are sometimes known as safety switches or a RCD. An earth leakage circuit breaker (ELCB) may be a residual-current device, although an older type of voltage-operated earth leakage circuit breaker also exists.