How to tell if a heat trace is working

To determine if a heat cable(heating trace) is functioning properly, use a combination of physical checks, electrical tests, and temperature monitoring. Here’s a step-by-step guide:

1. Visual and Physical Checks

- Feel the Pipe or Cable:  

  - Working: The pipe or heat cable should feel warm (not hot) to the touch when active.  

  - Not Working: If the pipe feels cold and ambient temperatures are below freezing, the cable may be faulty.  

  - Caution: Some self-regulating heating cables only warm slightly unless it’s very cold.  

- Check for Ice or Condensation:  

  - Working: Pipes should remain ice-free, and gutters/roofs should show melted snow/ice in de-icing applications.  

  - Not Working: Ice buildup or frozen pipes indicate the heat cable is inactive.  

- Inspect for Damage:  

  - Look for frayed wires, burnt spots, or loose connections. Damaged cables may short-circuit or fail.  

2. Use a Multimeter

Test the electrical continuity and power draw of the heat cable:  

1. Turn Off Power: Disconnect the heat cable from its power source.  

2. Test Continuity:  

   - Set the multimeter to ohms (Ω).  

   - Place probes on the cable’s live and neutral wires.  

   - Working: A reading between 10–100Ω (varies by cable length/wattage).  

   - Not Working: Infinite resistance (OL) means the cable is broken.  

3. Test Voltage:  

   - Reconnect power and set the multimeter to AC voltage (V~).  

   - Measure voltage at the cable’s terminals.  

   - Working: Matches the rated voltage (e.g., 120V or 240V).  

   - Not Working: No voltage indicates a tripped breaker, faulty thermostat, or wiring issue.  

3. Monitor Temperature 

- Infrared Thermometer:  

  - Aim at the pipe or cable surface.  

  - Working: Temperature should rise 5–20℃ (9–36℉) above ambient (depending on cable type).  

- Thermal Camera:  

  - Visualize heat distribution. A working cable will show a consistent warm line along the pipe.  

- Thermostat/Controller:  

  - Check if the thermostat is activating the cable when temperatures drop below the set point.  

4. Check Power Consumption

- Clamp Meter:  

  - Measure current (amps) flowing through the cable.  

  - Working: Matches the cable’s rated wattage (e.g., 5–20W per foot).  

  - Not Working: Zero amps or significantly lower than rated.  

5. Observe System Behavior  

- Self-Regulating heating Cables:  

  - Should warm up only in cold spots(e.g., where ice forms).  

- Constant Wattage heating Cables:  

  - Should maintain a steady temperature along the entire length (if paired with a thermostat).  

6. Look for Warning Signs  

- Tripped Breakers: Frequent tripping suggests a short circuit or overload.  

- High Energy Bills: A working heat cable uses minimal power unless in extreme cold. Sudden spikes may indicate inefficiency.  

- Error Codes: Digital controllers may display faults (e.g., “open circuit” or “overload”).  

Troubleshooting Common Issues  

When to Call a Professional

- If electrical testing reveals a dead cable or complex wiring issues.  

- For large-scale systems (e.g., industrial pipelines, roof de-icing).  

- If you’re unsure about handling live circuits.  

Final Tip

Heat cables are designed to work silently and efficiently. Regular seasonal inspections and pre-winter tests ensure reliability. Always follow the manufacturer’s guidelines for your specific cable type!  

Safety First: Turn off power before inspecting or testing the cable.