A surge protector is an appliance or device designed to protect electrical devices from voltage spikes. A surge protector attempts to limit the voltage supplied to an electric device by either blocking or shorting to ground any unwanted voltages above a safe threshold. This article primarily discusses specifications and components relevant to the type of protector that diverts (shorts) a voltage spike to ground; however, there is some coverage of other methods. A power bar with built-in surge protector and multiple outlets is a common type of surge protector. The terms surge protection device (SPD) and transient voltage surge suppressor (TVSS) are used to describe electrical devices typically installed in power distribution panels, telecommunications systems, and other industrial systems, for the purpose of protecting against electrical surges and spikes, including those caused by lightning.