A spike is also known as an impulse. It is an instantaneous, dramatic increase in voltage. Similar to the force of a tidal wave, a spike can enter electronic equipment and damage or completely destroy components. Spikes are typically caused by a nearby lightning strike. Spikes also occur when utility power comes back online after having been knocked out in a storm or as a result of a car accident.
Spikes can cause devastating damage to hardware and loss of data.
High-powered electrical motors such as air conditioners or household appliances cause surges. When the equipment is switched off, the extra voltage is dissipated through the power line. Computers and other sensitive electronic devices are designed to receive power within a certain voltage range. Electrical noise disrupts the smooth sine wave usually expected from utility power. Electrical noise is caused by many factors and phenomena, including lightning, load switching, generators, radio transmitters, and industrial equipment.