An electrical testing company owner says about 10 per cent of electric blankets brought to him for checks are failing thermal inspections. 

MegaTest’s Kevin Johnson said thermal imaging could show when coils within the blankets had moved and were crossed over or touching each other, creating potentially dangerous hotspots. 

The revelation comes after a coroner’s report was released today about an 82-year-old Wellington woman whose electric blanket caught fire while she was in bed. Ann Davies McAllister and her dog died from smoke inhalation in January last year. 

This thermal image shows an electric blanket that has coils in a good condition, not touching each other. Image / MegaTest 

Johnson said the “tragic” story served as an opportunity to encourage people to have their electric blankets thermally imaged, as a visual check was unlikely to show if there were issues with the coils inside the blanket. 

He has tested about 60 blankets this season and said he failed about seven of them. While people are advised to replace their electric blankets after about five years, Johnson has failed some that are only three years old. Meanwhile, one blanket he described as looking almost brand new in its thermal imaging was more than a decade old. 

The amount of issues he was spotting with coils was “quite alarming”. 

When coils touch or overlap, they create hotspots, which could lead to overheating and possibly fire, he said. 

Multiple factors caused the fast deterioration of an electric blanket, including leaving them on the bed year-round, or folding them for storage instead of rolling them. 

McAllister’s electric blanket was about 11 years old when it caught fire. Her daughter, worried about how old and worn it was, had bought her a new one and believed she was using it, only to discover it still in the cupboard after her mother’s death. 

Fire and Emergency community education manager Adrian Nacey said blankets should be turned off before anybody got into the bed, should be laid flat, and the controls and cords should not be twisted or caught between the mattress and bed base. 

Thermal imaging shows a hotspot caused by touching coils inside the electric blanket. Image / MegaTest 

People could check for hotspots in the blanket by turning it on high for 15 minutes, then switching it off and running a hand over it, he said. 

Blankets should be less than five years old and should be replaced or checked by a registered electrician at the first sign of wear. 

They should always be rolled for storage, instead of folded. 

This story was originally published on the Herald, here