APPLIANCE WIRING MATERIAL
Style 2642 Multiple conductor with extruded insulation
Rating 105 deg C, 300 Vac, Horizontal flame.
Conductor Resistance Wire. 16-10 AWG. Copper alloy, nichrome, or other suitable resistance wire element wound around the insulation; size and number of turns dependent upon wattage demand.
Insulation Listed Type SPT-3 , No. 10, 12, 14, or 16 AWG
Assembly Two conductors. The cable is assembled with the heating element by one of the following methods: (1) The PVC insulation is carefully removed along the length of the SPT-3 cord so as to bare the conductor for approximately 1/2 inch of widths at periodic intervals. A spirally wound nichrome or other type of resistance wire is then carefully wound the length of the core, and may be soldered to the exposed conductor. The number of turns per inch will determine the watts per foot of heating cable. (2) Over the two parallel copper conductors, an adhesive-backed copper tape 1/4 inch by 0.0025 inches thick is applied as a band at periodic intervals with the adhesive side down against the PVC insulation. Dependent on the AWG size of the SPT-3 conductor, a staple made of “monel” metal or stainless steel is driven through the insulation of one of the copper conductors and over the adhesive-backed copper tape at a slight angle to the conductor. The staple will protrude through the insulation and the points are bent over on the underside. Size of stable in inches for 10 AWG, min. length 0.5, thickness 0.050, width 0.024; 12 AWG, min length 0.375, thickness 0.050, width 0.024; 14 AWG, min length 0.3125, thickness 0.050, width0.024; 16 AWG, min length 0.3125, thickness 0.050, width 0.024. A nichrome or other alloy resistance wire is then spirally wound around the SPT-3 cord and the copper banding tape. The number of turns per inch will deter mine the watts per foot of heating cable. A second tape of either adhesive-backed copper or TFE tape is then wrapped over the heating element wire and the “monel” staple completely covering the first copper tape. This assembly is repeated alternately along the conductor. The second tape coverig is simply to hold down the resistance wire and make contact with the “monel” staple and first copper tape.
Covering Optional, 13 mils thicness minimum at any point of extruded PVC.
Jacket PVC, 40 mils minimum average thickness, 32 mils thicness minimum at any point.
Standard Appliance Wiring Material UL 758.
Use Pipe heating cable where the acceptability of the combination is to be determined by Underwriters Laboratories Inc.
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