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Heated mat layout and circuit planner
Give it the area you want kept clear and the breaker it has to run on. It works through every mat on file and returns the ones that fit, what they cost, and what the wiring has to look like. Sizing is done on the top of each manufacturer's stated amp band, not the middle — a breaker sized on a number the manufacturer never promised is not sized.
| Mat | Qty | Covers | Amps | Circuits | Price | $/sq ft |
|---|
Enter a length and width.
The two rules that decide this
Circuit constraints
- A snow-melting mat is a continuous load, so it gets 80% of the breaker
- Anything running three hours or more is a continuous load, and a continuous load may not exceed 80% of the breaker rating. A 15 A circuit carries 12 A of mat, not 15; a 20 A circuit carries 16 A. The Summerstep owner's manual on file states the same rule, so this is not our reading of the code. Most mat listings quote a raw amp figure and leave you to discover this.
- At 41 sq ft the protection changes, and so does the job
- At 41 sq ft and above, the installation needs Ground Fault Equipment Protection rather than a Class A GFCI. NEC 426.28 permits GFEP only on a fixed installation with a dedicated branch circuit and a secured receptacle labelled “For Snow-Melting Equipment Only”. This is the point where a driveway layout stops being something you plug into an existing outdoor outlet, and it is the single most expensive surprise in a mats plan. Have a licensed electrician do the circuit work. Below that line, at or under 40 sq ft of mat on a circuit, HeatTrak’s electrical guide accepts a Class A GFCI — the 4–6 mA kind already built into most outdoor receptacles and into the HR-P power unit.
Describing the rule is as far as this goes. Hardwired and 240 V work belongs with a licensed electrician, and the price column below does not include any of it.
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