Best pipe cable with thermostat in roof and pipe heat cables
A short plug-in pipe heat cable with a built-in thermostat, for a single exposed water pipe in a crawl space, garage or against an outside wall. Fit it flat and to length: it must never be wrapped or doubled.
Our score: 7.2/10 out of 10Researched, not lab-tested
- Use
- Water pipes
- Cable type
- Constant wattage
- Cable length
- 6 ft
- Output
- 7 W/ft
Is it right for you?
Pros
- Built-in thermostat: on below about 38 °F, off above about 45 °F
- For metal pipe or Schedule 40 plastic supply pipe, 3/8 to 1 1/2 in across
- Lighted plug shows the cable has power
- Sold from 3 ft to 30 ft (HC3A to HC30A)
Cons
- Constant wattage: never spiral, overlap or double it, even briefly
- Can't be longer than the pipe; pick the length from Frost King's chart
- Not for drain lines, hoses, mobile-home feeds, or inside walls and floors
- 12-month replacement warranty; labour and installation not covered
- Best for
- Owners with one short, accessible water supply pipe that freezes in cold snaps, such as a line in a crawl space or an unheated garage.
- Not for
- Long or hidden pipe runs, pipes inside walls or floors, drain lines, hoses or mobile-home water feeds.
Our verdict
The Frost King HC6A is a 6 ft, 120 V pipe cable at 7 W per ft, with a thermostat that switches it on when the pipe falls below about 38 °F and off above about 45 °F, and a light in the plug that shows it has power. It is for water-filled metal pipe or Schedule 40 plastic supply pipe from 3/8 in to 1 1/2 in across; Frost King rules out drain lines, fuel lines, hoses and mobile-home feed lines.
The catch is that it is constant wattage. Frost King’s rules are strict: pick the length from its chart, never use a cable longer than the pipe, and lay it straight along the pipe, never spiralled, overlapped or doubled, because over-wrapping can overheat it. If your pipe is longer or awkward to match, the self-regulating Raychem FrostGuard FG1-6P may overlap and can be spiralled. Our guide to keeping pipes from freezing in an outage covers what a cable can and cannot do when the power is off.
Fitting it safely
Hold the cable flat against the pipe with Frost King application tape or electrical tape rated to at least 176 °F (80 °C), at about 6 in intervals; avoid masking tape, and don’t pull cable ties tight enough to cut it. Cover cable and pipe with 1/2 in fiberglass or other non-flammable pipe insulation with a vapor seal. Never bury the cable, let it touch the ground or install it in walls, floors or ceilings, and don’t use it where a hot-water pipe runs above 155 °F.
Safety: every fall, check the cable unplugged for cracked or charred insulation or bare wire, and replace a damaged cable at once, as the US Consumer Product Safety Commission advises.
We found no safety listing mark in Frost King’s text for this kit; CPSC advises using tapes certified by UL, CSA or FM, so check the box for the mark. To test it, plug it in, uncover the thermostat block and hold a bag of ice on it: after about 20 minutes the cable should feel warm. If the plug light is off, check the power and whether the GFCI has tripped. Other cables are on our heat cable page.
Specs
Frost King Automatic Electric Heat Cable Kit for pipes, 6 ft (HC6A)
Use
| Use | Water pipes |
|---|---|
| Cable type | Constant wattage |
| Pipe types | Metal or Schedule 40 plastic supply pipe, 3/8 in to 1 1/2 in OD |
| Largest pipe | 1.5 in |
Electrical
| Output | 7 W/ft |
|---|---|
| Thermostat | Built in: on below about 38 °F, off above 45 °F |
| Voltage | 120 V |
Other details
| Cable length | 6 ft |
|---|
Maker’s figures, checked 4 Nov 2026.
Frost King HC6A questions
Can I put insulation over the cable?
Yes, Frost King asks for it: cover the cable and pipe with 1/2 in fiberglass or other non-flammable pipe insulation with a vapor seal.
Can I use it on plastic pipe?
Frost King lists water-filled metal pipe and Schedule 40 plastic supply pipe from 3/8 in to 1 1/2 in outside diameter. Other plastics are not named, so check with Frost King before fitting it to them.
Can I wrap it around the pipe twice?
No. Never spiral, overlap or double it up, even on a short section, and never use a cable longer than the pipe; over-wrapping can overheat it.
How do I know it is working?
The plug light should be steady. To test the thermostat, uncover it and hold a bag of ice on it; after about 20 minutes the cable should feel warm. A flickering light means the cable may not be working and should not be installed.
