Underfloor heating Modern underfloor electric heating is not a source of EMFs, but some systems installed in the past can be a source of magnetic field.In the past, underfloor heating systems sometimes used a single heating wire, laid round the floor area in a big loop to come back to the connection point: Because this makes a single big loop, it was a source of magnetic field (the wire used was usually screened so there was little electric field).Nowadays, a different system is used, where the "go" and "return" conductors are in the same cable. Instead of having to come back to the connection point, the cable simply zig-zags across the floor and stops: There is now no loop, and because the currents in the cable are balanced, there is negligible external magnetic field. See also:fields from appliancesfields from house wiringfields from other sources