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. A surge suppressor prevents the peak AC voltage from going above a certain threshold such as plus-or-minus 200 volts. Semiconductor devices are used for this purpose. The power line is effectively short-circuited to electrical ground for transient pulses exceeding the threshold, thus saving the electric wiring.