unit shown ballast resistors 13 and 14 each comprise a helically wound resistive wire 15 on a reinforced strip 8 of the present invention a housing 16 comprises a pair of outwardly oppositely extending resistor holders or wing portions 17 and 18 and a central portion 19 the housing 16 is extruded in a secondary process as a unitary member in which the ballast resistors 13 and 14 and a metal strip 20 are pulled through the melt flow and die not shown used to form the extruded housing the housing is preferably formed of a thermoplastic insulative material the temperature of the melt flow in this secondary extrusion process is sufficient to soften or melt the thermoplastic insulative material of the reinforced strips 8 thus without the reinforcing strands the strips would be subject to stretching and elongation resulting from the forces involved in the secondary extrusion process this in turn would stretch the resistive wire 15 wound on the strip and would cause the given value of resistance per unit length of the ballast resistors 13 and 14 undesirably to vary it is necessary to maintain a constant value per unit length for the ballast resistors in order for the lamp 21 mounted on the housing to operate properly for considerations of heat dissipation and electrical operation the ballast resistors 13 and 14 must be positioned a minimum distance from the outer surfaces of the resistor holders 17 and 18 the ballast resistor using a reinforced strip 8 of the present invention is thinner than a ballast gluing reinforcing strands over the resistive wire on both sides of a strip of material and.