Constant wattage heating tape cables are constant watt arrangement designed to put out a certain amount of wattage per meter of cable. These are generally constructed of two #12AWG polymer insulated parallel bus wires with a nickel alloy heating element wire wrapped alternatively along the insulated bus wires. These connections are made at the ‘NODE’ point where the nickel-alloy heating element is either welded or connected by rivets. The entire element assembly is then dielectrically insulated with an additional polymer jacket. The parallel resistor arrangement has two distinct advantages.
- The power output per unit length is constant, regardless of the overall length of the heating unit
- The parallel arrangement preserves systems probity i.e. if any section of cable should fail, the rest of the heater will continue to work. This is an important advantage over series circuits.
The output ratings of these cables depend on the resistance of nickel alloy wire and the amount used between node connections. These cables can be cut to any convenient length in field within the limits imposed by the maximum heating circuit length, and minimum bus-bar connection interval. When terminated the last 1 meter heater.