Nelson wrote in message
.com...
On Wed, 26 Jul 2006 02:35:52 -0400, Franc Zabkar wrote
(in article ):
On Tue, 25 Jul 2006 12:25:30 -0400, (Fred McKenzie) put
finger to keyboard and composed:
James Sweet wrote:
Ah it's the greatest thing in cold winters, the wires are heavily
insulated, they're inside a blanket, and over a sheet. Cloth doesn't
conduct, what are the chances of actually getting electrocuted?
James-
I think the chances are slim, but the OP had a special problem.
Considering the risks, one might decide to avoid use of an electric
blanket in some circumstances, unless there was an additional plastic
sheet between the user and the blanket. (The alternative of
non-electric
blankets may be an undesireable choice due to the additional weight
required.)
I'd suggest dispensing with the electric blanket and pre-warming the
bed with a portable fan heater.
- Franc Zabkar
I appreciate all those who have given constructive suggestions. For
the record, my wife has Multiple Sclerosis one symptom of which is poor
blood circulation. She is always "cold" even in the summer. More
blankets, which only keep body heat in, don't help. What is needed is
a heat source other than her body. Hence the electric blanket. She
still complains it isn't warm enough and I have no idea how to test if
it is working properly merely from a heating perspective. It feels
warm but not hot. I assume, without taking the thing apart, that there
are a bunch of resistive elements wired in parallel. Thus some could
be open and the blanket still heat.
The other concern is safety since, unfortunately, another of her
symptoms is incontinence.
The blankets we have are perhaps 20 years old. They still seem to work,
but do not get very warm. On the other hand, I don't recall how warm
they are supposed to get. I am sure they are regulated so that you
don't inadvertently burn yourself from a high setting. I would have
just gone out and bought a new one if money weren't an issue.
In searching the web, I noticed many Electric Utilities offer "safety
tests" for electric blankets, so there must be some protocol. I was
just hoping someone here knew it although it is hardly "electronics".
Another article I found suggested that they "used to be unsafe" but
newer standards have been adopted which make them safe.
Leaving out the "tin foil hat" concern about electromagnetic fields, I
assume the main risks are shock and fire. My presumption was that the
UL certification covered those and the ones I have carry UL
certification.
I suppose the best thing to do is to just buy a new one. And yet,
without understanding the failure modes of the old ones, there still
remains in my mind a safety concern.
--
Nelson
My recommendation would be a mixture of low tec and high tec and no electric
blanket.
A conventional hot water bottle to pre-heat the bed and an underblanket of
reinforced mylar space blanket.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/