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Ian Malcolm[_2_]

wrote in
:

On Mon, 10 Dec 2012 11:06:54 +1100, John G
wrote:

After serious thinking wrote :
Greetings,
My wife uses foot baths in her shop and the heaters fail on them.
The style of foot bath she likes best is no longer available. The
baths all seem to be made by the same company, Helen of Troy. Model
61320. Anyway, I took a couple apart to look at the heaters and they
appear to be ceramic power resistors. They are marked "20W200 ohms"
, except the ohms symbol is used. The foot baths only draw 78 watts
and there is a vibrating doodad inside too. There is a bimetal
switch in series with the resistor. The switches are inside a tube
of some sort of heat resistance woven stuff. Does it make sense that
what I think are ceramic encapsulated power resistors are exactly
that? I'm thinking I should buy a couple and see if they work. I
would also like to be able to replace the bimetal switches and the
heat resistant tubing as well but I don't know what to call the
tubing. Thanks,
Eric

Eric,
A footbath is a great place to strart a trip thru electrocution to the
morgue.
I there is ever an acident the first place the investigator will look
is who repaired it.

For your own happiness DON'T DO IT. :-?
I thought about that. But there is really no other foot bath that has
the same ease of cleaning and if I replace the resistor wrongly enough
to maybe cause power to enter the water then the circuit breaker and
the GFI woiuld trip. The cleaning is super important. My wife has to
disinfect each foot bath after a client uses it and before another
client can put their feet in it. Fungus infections are particularly
troublesome. My wife has never failed to sterilize her tools and has
never had a client become infected from her shop. So she needs tools
that are easy to sterlize and one thing that makes tools hard to
sterlize are crevices which her current foot baths do not have but
which all the new ones do.
Eric

I assume you are in 120V land!

A simple calculation (P=(V^2)/R) shows the resistor probably dissipates
72 watts which would correspond neatly with your observed 78W draw.
However the originals are only rated for 20W - no wonder they fail!

You do not know what extra testing has been done by "Helen of Troy" to
qualify these resistors for use at 3.6 times their rating, nor do you
know if a third party's 20W 200 ohm resistor will fail safe.

If you had appropriate professional liability insurance for small
medical appliance repair you would run away screaming from a customer
who asked you to fix a device that overran a heater by that high a
factor using unapproved parts.

The fact that you belive the GFI can be relied on to backstop your
possible shoddy workmanship means I can be certain that you are not a
fit and competent person to repair these appliances.

Basically you are putting all your assets on the line. Your home, your
wife's business etc. and because she let you work on them, she's
negligent as well if they are ever put back into service.

Find a company willing to repair them (if you can) and make sure they
have appropriate insurance or forget about it. --
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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