Heat Tracing Power Calculation: How to Size the Cable Output

Frequently Asked Questions

1. How is the required power per metre calculated?

Heat loss depends on pipe diameter, insulation material and thickness, maintain temperature and minimum ambient temperature. We compute Q per metre and then select a cable whose output at the maintain temperature exceeds that value with a safety margin.

2. Why does the same cable give different output on different pipes?

Self-regulating cable output falls as its temperature rises. At a higher maintain temperature the same cable delivers fewer watts per metre, so the selection must be based on the output at the working temperature, not the nominal value.

3. What safety margin should be applied?

For outdoor and exposed piping we recommend 20-30 percent margin above the calculated heat loss, to cover wind and ageing of the insulation.

4. Do you provide the calculation sheet?

Yes. We issue a heat loss calculation sheet together with the cable selection, so it can be included in the project design package.