Lightning and Power Surge Damage to Appliances

Lightning rarely damages appliances by direct stroke to the appliance. Damage is usually caused by direct strokes to the power lines or by induced surges. Induced surges are caused by the release of bound charges on the line when overhead clouds lose charge because of a strike to objects other than the line. The direct stroke produces a large voltage, while induced surges usually have a lower magnitude voltage. Lightning usually damages appliance electrical insulation which leads to a continuation of the damage by the 60-Hz power that has the appearance of a non- lightning-related failure. Lightning or power surge damage can probably be ruled out if the equipment has failed because of certain problems such as an open conductor or a bad bearing. Electric lamps can provide a clue as to whether a high-voltage surge occurred in the electrical system because the filaments often open when subjected to such surges. Equipment can be protected by a design to withstand the highest normal voltage spikes expected. Proper grounding and bonding also is important. For critical components or equipment, surge arresters may be required.