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How to Troubleshoot Common Heat Cable Malfunctions

Updated: Jun 14, 2023

With winter in the rearview, it’s easy to focus on outdoor parties and the beach, but don’t forget winter is never really far away. If you live somewhere in the Great Lakes Region, the Rocky Mountain West, or any other cold climate, you understand: You want your brand new heat cable system in top shape before the next snowstorm, not after.

By running your system through the paces every few months, you’ll be able to troubleshoot issues a lot easier than you would in the middle of a blizzard or with two feet of snow already on your roof. These issues could include switching on your heat cable only to have nothing happen or seeing it power up just fine but sputter out a few minutes later. We talked with the professionals at Heat Cable, and they shared some of the more common roof winterization malfunctions they have encountered and how to fix them.

Roof Cable Incorrectly Installed

Your snowmelt needs a clear path from your roof to the ground, and haphazard installation will prevent that from happening. If your roof cable only extends to the edge of the eave and not into the gutter, it may not be able to keep an ice dam from forming along the edge of your roof.

For the heat cable to be effective, it’s usually laid out in a series of zig-zag patterns along the eave’s edge at about 2-foot intervals. The cable should form a loop at the tip of the triangle closest to the gutter and extend a few inches over the roof rim into the gutter, often referred to as a drip-loop. This, coupled with the heat cable running through the channel and the downspouts, will keep things warm and not allow water to back up and form an ice dam.

Circuit Tripping

Another common problem our technicians see with heat cables is circuit tripping. Your heat cable should be connected to a circuit interrupter, which breaks the circuit any time there is an imbalance between incoming and outgoing current. The National Electric Code calls for different levels of ground fault protection depending on what type of heat cable you have.

The timing of the circuit trip can be very informative.

Instantaneous circuit trips are most often caused by a ground short somewhere in the system. This means you need to take a good look at the cabling itself, as well as the power wiring. Look for breaks, cracks, or cut in your cable, loose connection points, and frayed or broken wiring. You’ll also want to check the circuit housing, especially if it’s outside. Moisture, contamination, or contact between the wires within the circuit box can short out the circuit.

If the circuit trips a few seconds to a minute after powering on the cable, there are a number of things that could have happened. The most common thing that we have seen is that there is too much power draw on the circuit. Usually this is because more cable was installed than for which the circuit is rated. Another common cause is that the cable has simply gone bad.

Over time the interior of the cable can break down and stop functioning properly. We have even seen cable damaged in such a way that water has entered the cable and turned to ice, which takes some time to melt before the water can short the circuit and trip the interrupter.

At the end of the day, a tripped circuit means that your heat cable is not working as intended. We always recommend resetting the interrupter, but constant or persistent tripped circuits may mean you need to have your system inspected and make any repairs.

Circuit Temperature Too Low or Too High

There are a variety of reasons why the circuit temperature may be too low or too high in a self-regulating heat cable: A temperature sensor is not in the right place, or it is wired incorrectly; the heat cable is connected to the wrong voltage or not connected at all; the thermostat or process controller setpoint is not correct, or the thermostat is wired wrong.

First, check your thermostat to ensure it’s set at the right temperature and wired to close when it reaches its setpoint. Next, test the cable connection box’s power and the cable end seal to ensure the cable is connected to power. Finally, check the temperature sensor’s placement to ensure it’s in the correct area and go over its wiring to see that it matches up with the manufacturer’s directions.

It’s important to remember to turn the power off before attempting any of these fixes and to have a partner with you in the event you have to climb up onto your roof. We doubt that a hospital visit is part of your summer plans, so safety first. After spending a substantial amount of time and money installing quality heat cable on your roof, you want it to work flawlessly and for a good, long time. The fixes we shared should do precisely that.

If, after checking everything and your heat cable still isn’t working correctly, contact your installer or other roof heat system professional. When it comes to heat cable, it’s likely they have seen it all and are equipped to fix whatever’s wrong.

For more information on DIY heat cable installation and other roof winterization projects, stay tuned to’s experts.

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