Patent ID: 8338759

Claim:
A heating cable for high temperature environments, the heating cable comprising: a bus wire structure comprising: a plurality of bus wires; and a first insulation layer for the plurality of bus wires, the insulation layer including a plurality of node areas, the node areas exposing portions of the bus wires from the insulation; a heating element wrapped around the bus wire structure in a helical manner, the heating element comprising: an insulating core; and a plurality of resistance wires wrapped around the insulating core in a helical manner; a second insulation layer comprising a tape wrapped around the bus wire structure and the heating element; and a corrugated metal sheath enclosing the bus wire structure and the heating element, wherein the heating element is electrically coupled to the nodes of the bus wire structure by coupling the plurality of resistance wires to the bus wires at the plurality of node areas to create a plurality of resistance zones, wherein a plurality of redundant paths in between two nodes are provided to allow for current to flow in a zone if one of the redundant paths is broken.