... to spikes will damage electronic equipment and corrupt data. What causes it? Switching on/off of nearby equipment, lightning, motors ... voltage (milliseconds to seconds, minutes, hours or days).What causes it? Most commonly an over -strerched utility, espevially in ... lightning peoduces spikes/surges, over-voltage or power cuts, What cause it? the surgeis gengrated bu either a directhit, or indirectly ...