Hi All,

I heard back from Biddeford today, although the person wasn't very
knowledgeable (technically).

He was elusive and well versed on the writings at:

https://biddefordblankets.com/pages/our-technology

He told me that the blanket does indeed have 4 pins on the connector,
two for the heating element itself and the other 2 are for the 'sensor'.
He said the sensor was temperature sensitive type. But, after a lot of
cross examination, he finally admitted the sensor is not a sensor, it's
a one time use fail safe and that all their products will fail if they
are bunched up. I asked him if 'bunched up' meant just rolling over on
top of the blanket, and he said YES!!! I'm not sure how any manufacturer
can make a bedding product that is susceptible to fire if the owner
rolls over onto the blanket, which forces the wires together and makes a
hot spot...that will later fail at the point where the wires crossed.
Expecting the blanket to remain perfectly flat while the owner sleeps
seems inappropriate.

And, the rep also admitted they use very low melting temp insulation, so
that the blanket will fail on purpose. In other words, it is designed to
fail!

I'm not sure how UL considers this safe.

My blanket however had no connections to the spiral wrapped sensor
wire-which is why the controller didn't shut the blanket down!! The rep
didn't believe me, but the 2 connector pins designed to allow the
connector to pass the sensor signal to the microprocessor had no wires
connected to them, the 'sensor' was never hooked up!

I wish I had saved all the parts and taken some pictures!!!
Unfortunately, I didn't.

TY all who commented, I'm now looking for dual detector smoke alarms for
my house. With the amount of smoke in my house, I was very lucky to
escape from the fire.

Regards,

Art


On 11/27/18 12:58 AM, Art wrote:
> I had a catastrophic failure of my electric blanket, and the autopsy of
> the damage leaves more questions than answers.
>
> I lost bedding and my mattress, while there were no open flames, it
> scared the living crap outta me. I woke up to amazing heat in my bed, in
> a very localized area very close to my body. All the damage was from
> melted synthetic bedding and mattress materials. The house was filled
> with smoke and fortunately I woke up quickly enough to escape without
> injury.
>
> I was able to remove the cable from the blanket, and it looks like it
> failed only in one location. The wire in the area of the failure was
> black and melted. In the area where the damage was the worst, there were
> 2 of the conductors melted together with almost no insulation left on
> the wires-it had apparently caught fire and burned totally away.
>
> I can only guess that the blanket wasn't laying flat and that the wires
> crossed, which created more heat in a small area. So, the insulation
> began to melt, eventually failing, which allowed the conductors to short
> together as the wires insulation became molten.
>
> I've used this brand of electric blanket for years, this is the third
> catastrophic failure I've had in the last 20 years. Although none of the
> previous failures were nearly as damaging as the latest one.
>
> The electric blankets are high end Biddeford brand products, were all
> the same model, the TC12BO controller, see:
>
> https://biddefordblankets.com/products/controller-digital-tc12bo
>
> All of the previous failures were quickly and briefly autopsied, but I'm
> feeling compelled to dig deeper after this last failure.
>
> All the blankets used heavy duty 600 volt rating on each of the 4 pins
> on the connector that runs from the controller into the blanket, a photo
> of the connector is here:
>
> https://duckduckgo.com/?q=3Dbiddeford+elecrtric+blanket+failures&t=3Dbrav=
e&iax=3Dimages&ia=3Dimages&iai=3Dhttps%3A%2F%2Fimages.bonanzastatic.com%2Fa=
fu%2Fimages%2F7714%2F7783%2FBiddeford__76PA_1.jpg
>
> Inside the controller is a PIC chip, triac switching and a mylar cap
> based line voltage to low voltage power supply. There is a thermistor
> mounted on the PCB, which is used to compensate for the ambient
> temperature change in the room. There are 2 output wires and the heating
> element is a single conductor (actually 2 parallel conductors) within
> the blanket itself. Although there are 4 terminals on the controller
> connector, only 2 of them are used. There are no connections to the
> other remaining pins on the blanket.
>
> Here's where it gets interesting............
>
> The heating element wire is actually made up of 2 conductors, each very
> very small. One is copper (or it appears to be). The other is some sort
> of silver color, likely tungsten or nichrome, or a combination of both.
>
> The silver colored wire, which I assume is the heating element is at the
> center of the heating cable, it is spiral wrapped with some sort of very
> small diameter multi stranded synthetic cord, with fibers so fine, I
> can't see the individual fiber strands. Around the core is a layer of
> what appears to be insulation. On the outside of that, the copper wire
> is spiral wound around the insulation, at about 6 turns per inch. Over
> that, is the outer sheath of the wire.
>
> The company has a PR type version of the controllers function, which
> sounds like crap to me....claiming that the insulation and the copper
> conductor signal the controller to shut down if a fault occurs. However,
> there is no signal path to the controller, even if the plastic
> insulating material was indeed some sort of temperature sensitive
> sensor. THE COPPER AND THE SILVER COLORED WIRES RUN IN PARALLEL WITH
> EACH OTHER, THERE IS NO SENSOR OR FEEDBACK METHOD FOR A SENSOR.
>
> In other words, there is no possible way for the controller to know that
> the 'sensor' is detecting a hot spot, there are only 2 active terminals
> in the blanket and in the controller output.
>
> The company's explanation is here:
>
> https://biddefordblankets.com/pages/our-technology
>
> The verbiage of the company makes it sound like there is an active
> sensor, but the heating element is 2 parallel conductors. There is no
> way to for the controller to know there is a hot spot in the blanket.
>
> At best, I think they can only detect a change in current flowing
> through the heating element, which can only occur after the electrical
> failure and is not reusable....a one shot deal. I know it's possible to
> make temperature sensitive self regulating heating elements, but the
> company strongly implies there is an actual 'sensor'.
>
> By the way, my smoke detector never went off!!!! I discovered that every
> single smoke detector in my house, including some pricey AC powered
> units is the ionization type, which are nearly worthless. I count myself
> as lucky to have learned this lesson without getting seriously injured
> or worse. I have 2 temporary smoke detectors (photoelectric) bought at
> the local hardware store and will do a more proper photoelectric
> detector buy and install soon. I urge all to weed out the ionization
> smoke detectors and to replace them with more proper photoelectric
> types. Any search engine, or youtube search will yield info regarding
> why the ionization detectors are being outlawed lately-to many people
> have died needlessly.
>
> Regards,
>
> Art
>
>
>
>
>



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