Sometimes I see a grey wire and purple wire with a Polivalve nozzle heater. What wires are those?

The wires with purple or grey color wire insulator are power wires. Typically a Polivalve heater that has a specific thermocouple color code set, will be delivered with power leads that have a different color, or have an identifying strip, mark, or heat shrink to help identify the power leads. Please note that if the power leads were identified by a strip, mark ,or heat shrink and the leads are cut, the identifying strip, mark, or heat shrink will be removed. In such case s it is recommended to add marker tape to each power lead for ease of future maintenance.