One danger of using heat tape on water lines includes the exposure of insulated wire when users leave the tape in place year-round. Other dangers include the cracks that can form, allowing moisture inside and causing short circuits. When the heat tape crosses itself, cracks can cause a house fire.
Heat tapes can provide a short-term solution for pipes that are in danger of freezing, as they contain an internal wire that provides heat to the pipes. The user plugs one end into an electrical outlet and wraps the rest around the pipe. A thermostat on the tape signals the power to turn on, and it is possible to leave this plugged in year-round.
Unfortunately, some people never remove them. Over time, as the tapes go through the expansion and contraction associated with the temperature changes in the seasons, as well as exposure to rain and other forms of moisture, the insulation becomes brittle. Cracks appear, and once moisture gets inside, the whole tape shorts out, leading to problems at the circuit box. If the wire comes in contact with itself, the exposure can cause enough sparks to ignite any building materials within range. Heat tapes caused approximately 2,000 fires, 100 injuries and 10 deaths each year during the 1990s.