HeatTrak HR10-30

SaferProducts.gov consumer incident report 20220327-704A2-2147357104. Severity: Incident, No Injury. Product: HeatTrak HR10-30 (https://heattrak.com/products/residential-heated-stair-mat). Incident: I had stacked three HeatTrak "Heated Snow Melting Stair Mats" (Residential Heated Stair Mat (10" x 30")) on top of each other, on a PVC/wood deck. The mats had been turned off by triggering the vendor-provided GFCI. However, the GFCI apparently was an electronic switch; a neighborhood power outage caused the GFCI to reset, resulting the mats becoming energized. They overheated, melting through and fusing together; they also damaged and melted the PVC coating on the decking. The pictures show the result (although the deck picture was taken after I had scrapped off the melted black mat material) A combination of events combined to result in this failure. First, I made the erroneous assumption that I could turn the mats on and off by using the GFCI test button. That had always worked for me; I did not realize that if there was a power outage, it would be reset. Second, I'm sure the vendor did not expect people to stack the units on top of each other. However, I had no idea they would get so hot as to self-destruct. Third, these mats should simply not be used with PVC wood-core decking.