an extra - low - voltage heating system that produces a reduced magnetic field and which uses three insulated copper wires , or equivalents , as heating elements . its low operating temperature , robustness and safety enable the system to be installed , for example , in floors and walls for the general heating of buildings , and in outdoor pavements , for snow - melting purposes , etc . the single - phase feeder busbars are configured to reduce the magnetic field around the feeder . a monitoring network continually checks the integrity of the heating system .