Heat Tracing Restart After Power Outage
After a winter power outage, the heat tracing system is the first thing to check and the easiest thing to mis-judge. A system that re-energises and shows current is not necessarily healthy: insulation may be wet, circuits may be bridged, and controllers may have lost their settings. This checklist covers the restart.
1. Before re-energising
- Check how long the power was off and what the ambient fell to: a long outage in deep cold can freeze lines even if tracing was correct.
- Check the panel for signs of water ingress, condensation or tripped devices.
- Check for visible damage: fallen cladding, damaged cable at walkways, ice loading on trays.
- Do not simply reset all breakers and walk away.
2. Measure before switching on
| Test | What it tells you |
|---|---|
| Insulation resistance per circuit | Moisture or damage from the outage |
| Continuity | Circuit still complete |
| Earth continuity | Protective path intact |
| RCD function | Protection still works |
A circuit with low insulation resistance should not be energised until the moisture is located — energising a wet circuit is how earth faults and cable damage begin.
3. Re-energise in stages
Energise groups of circuits, not the whole panel at once: a fault then trips a small group instead of everything, and inrush is limited.
4. Check operating current and temperature
Compare current with the commissioning record. A circuit drawing significantly more or less than expected is telling you something: a damaged cable, a bridged circuit, a failed thermostat.
5. Verify controllers and alarms
Controllers with battery backup may have kept settings; those without may have reset to default. Verify set points against the design, and test the alarm path after the outage.
6. Look for the freeze the tracing could not prevent
Even with correct tracing, an outage can freeze small lines, dead legs and instruments. Check the known weak points: impulse lines, sample lines, drains, and any line that had been identified as critical.
7. Record what happened
Log the outage duration, ambient minimum, circuits tested, values measured and any repairs. This record is what makes the next outage faster to recover from and supports any insurance or warranty discussion.
Common mistakes after an outage
- Resetting breakers without measuring insulation resistance.
- Energising the whole panel at once.
- Assuming controllers kept their settings.
- Not checking the alarm path.
- Ignoring small lines and dead legs.
Topic hub: Installation, Commissioning and Maintenance
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