Temperature excursion in a personal electric heating pad

Thread Starter

AscentGroup

Joined Nov 27, 2023
3
Here is the charred remains of a Tronic branded electric heating pad (like an electric blanket but much smaller) that suffered a temperature excursion. Fortunately I was present when it happened and alerted by the burning smell. What is the most likely cause? I think there's a bimetallic switch inside because I used to hear regular clicking sounds but then again, I suppose it could have been some sort of relay. My guess is that that whatever it was finally got stuck in the on/closed position. I think a better design would have incorporated a thermal fuse or something to prevent this kind of failure from ending this way. I have another one but I'm not sure I'm comfortable using it without another device to monitor it and cut the power when the temperature goes outside of the normal range.

2023-12-15 10.27.43.jpg
 

LowQCab

Joined Nov 6, 2012
4,075
I would throw-out your spare Heating-Pad and purchase another brand.
This junk could have easily killed You, or someone else.

Or, were You using it for some other purpose different than what it was specifically designed for ?
.
.
.
 

Thread Starter

AscentGroup

Joined Nov 27, 2023
3
I would throw-out your spare Heating-Pad and purchase another brand.
This junk could have easily killed You, or someone else.

Or, were You using it for some other purpose different than what it was specifically designed for ?
.
.
.
I was just using it to keep warm; it was between my back and my chair when it broke.

I don't think I'd trust any brand unless I knew exactly what safety features it had.
 

MrChips

Joined Oct 2, 2009
30,819
I was just using it to keep warm; it was between my back and my chair when it broke.

I don't think I'd trust any brand unless I knew exactly what safety features it had.
The designed is flawed. It should be designed for a maximum wattage output, not on a temperature limit cutoff switch.
 
Top