Hello kaptain kazoo
Standard and often mandated safety measure is to use the
GFI = Ground Fault Interupter.
It is an electronic monitor of a current flowing from the
hot wire to the 'ground'. When the monitor detects a current,
it shuts off the appliance. Any electrical socket in the bathroom
should have GFI and any equipment in the bath, which is connected
by wires to the outside of the bathroom should be connected to the
powerline by an GFI protected socket.
Description and picture of such socket is here:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gfi.html
A clear picture and simple description is here:
http://www.electrical-contractor.net/gfcipage.htm
GFI (also called GFCI) does not protect from voltage spikes, such as
may be caused by the lighting:
http://www.hanford.gov/lessons/sitell/ll00/2000-04.htm
The safest solution is indeed the mobile or cordless phone:
http://www.howstuffworks.com/cordless-telephone.htm
Early cordless phones had a privacy problem, which was solved
by use of the spread spectrum, as used in these models:
http://www.amazon.com/exec/obidos/search-handle-form/102-8934126-0594550
It is a simple and practical solution.
You can read different models here:
http://www.epinions.com/elec-Comm-Cordless_Phones-All
We used to take our cordless handset to the hot tub, with no problem,
until one day it fell in :-) but all we had to do was to replace the phone.
It is likely to work for you too.
Search terms:
GFI
GFCI
Cordless phone
hedgie |
Clarification of Answer by
hedgie-ga
on
13 Oct 2002 22:58 PDT
The component which will transfer the data while providing complete
electrical insulation is optocoupler.
http://www.fairchildsemi.com/products/opto/oi/oi.html
Optocouplers may be used to provide the circuit separation required by
IEC 60950. When used in this way they are considere safety critical.
http://www.i-spec.com/Product_Design/optocoupler.html
Optocoupler work by converting signal to light and then light back to
the
lectric signal.
Sometimes sold as Solid State Relays:
IST450, IST450A: 8 Pin Photo EDMOS Relay Optocoupler
One-way or bidirectional:
www.chipdocs.com/pndecoder/number/876.html
or
www.vishay.com/document/83828/83828.pdf
You may also build a fiberoptics link from parts in:
http://www.thorlabs.com/
or use an Infrared Transmitter
http://developer.apple.com/techpubs/hardware/Developer_Notes/Macintosh_CPUs-G4/PowerBook_G419Dec00/PBG4-39.html
and
http://www.chevelles.com/techref/tecref26.html
or Blue tooth link
http://www.bluetooth.com
You may also consider wireless PBX
http://www.etsound.com/pbx/Wireless-Pbx-Phones.html
Using strict logic, the links above provide the answer to your
question:
How to transmit the data betwen devices while providing complete
electrical
insulation. In practical sense, the radiophone is doing that, just
using a
different part of the spectrum, and comes ready made. So, unless you
insist
on KXT7020E attached to a KX-TA624 PBX, radipone looks like an easy
solution.
You may stay with panasonic products:
http://www.telephones.com/cordless.htm
|
Request for Answer Clarification by
kaptainkazoo-ga
on
20 Oct 2002 17:22 PDT
The answer didnt really add anything that wasnt in the question.
Specifically: Use of GFCI was covered in the question. THe
explanation of how a GFCI operates isnt correct; a GFCI detects
current imbalance in the hot and neutral connectors. The exact model
of the phone required to be used was stated. It is fair to state that
an opto-isolator will provide the necessary degree of electrical
isolation, but there are no pointers to construction of such a device
that would be compatible with the stated phone system.
Finally, the question was "Is there any safety barrier I can purchase
that
will provide the required degree of safety?". I consider that
purchase does not include I design and build it myself; thats exactly
why I asked the question in the form its in. I'm looking for a
barrier box, like an intrinsically safe barrier I can purchase for a
4 wire hybrid phone system. It is possible such a thing does not
exist; I have hunted high and low and failed to find such a beast.
The general topic of "phone in bathroom" has come up a good few times
in usenet over the years; the thread is almost always more heat than
light. i'd recommend trying a google groups search on keywords 'phone
bathroom safety' for a suitable example.
|
Clarification of Answer by
hedgie-ga
on
21 Oct 2002 08:26 PDT
Dear Kaptain,
You are absolutely right that GFCI was described in the
question.
When I realized that, I added the 'explanation of answer' on
isolators.
The "inbalance" of the currents in hot and neutral implies the
existence
of leakage current, since charge is conserved. The two decriptions do
not
seems to be in conflict. However, GFCI, as well as instructions for
building
a box seems to be irrelevant now, thaqt youe explained you want to buy
a ready
made box.
There are such boxes on the market. For example:
http://216.239.51.100/search?q=cache:ijNhlpyiHI0C:www.malighting.de/home/support___service/manuals/DMX/130421e.pdf+optoisolator+box&hl=en&lr=lang_en&ie=UTF-8
I think I can find a out-of-box radiolink or infra-link, but I do not
see why a wireless
phone is not a satisfactory solution. I would appreciate a
clarification of the
problem before I invest addional time into a search.
hedgie
|
Request for Answer Clarification by
kaptainkazoo-ga
on
12 Nov 2002 15:44 PST
There is much poor understanding of the terms and opeartion of GFCI
(aka RCD) and ELCB. They are different animals, and do work in
different ways. It has not been legal to install an ELCB for general
ground fault protection here in the UK for a decade or two. A good
explanation of the devices can be found here:
http://groups.google.com/groups?selm=36f0329a%40news1.us.ibm.net
A wireless solution is not acceptable because (a) it means the target
phone is not a Panasonic KXT7020E, and (b) there is a problem of
keeping the battery powered thing charged. Until you've lived with a
Panasonic (or other similar phone system) you dont see why having the
right terminals is a Big Deal, but trust me, it is :-)
I've now given up on finding an appropriate barrier, and have adopted
system-wide methods of protection.
|
Clarification of Answer by
hedgie-ga
on
13 Nov 2002 06:16 PST
Hello Kaptain
Indeed, the two RCD and ELCB are two different animals.
Moreover, GFCI works differently in 120V and 220V
power nets, as described in additional detail here:
https://answers.google.com/answers/main?cmd=threadview&id=76124
Here is a schematic, which illustrates and confirms your description
http://www-training.llnl.gov/wbt/hc/Electrical/GFCIworks.html
I am glad you find a satisfactory solution and I am sorry I was
not able to make a contribution to what you already know. It is still
not clear to me how your solution avoids both problems, chore of
changing a battery and danger of being connected to the power net.
hedgie
|
