"Rich" writes:

AZ Nomad wrote:
On Mon, 11 Dec 2006 19:08:42 -0600, Jim myplace@home wrote:


Just a short note here. I constantly talk on the phone while
lazing in my hot tub. The phone is NOT cordless. So am I putting
myself at risk talking on the phone while in the hot tub?
Thanks...Jim

Yes. There's 90V and lethal current available on the phone loop.

No its 48 volts to stay under the limit of 50 volts for working live permits
etc.

You're both right. 48V DC is the loop voltage when the phone is on
hook. Pulled offhook this drops to under 10V. Ringdown voltage is
90V superimposed on that 48VDC so you've got peaks of 138V.

Traditional phone near bathtub = bad idea.

Ventricular fibrillation of the human heart only takes a macroshock of
100 to 300 millamps. While human skin dry is normally around a
megaohm, wet skin can make ya under 1kohm in impedance. V=IR and
all, 138V / 1000 ohms = .138A = 138mA if your phone slips into the tub
and someone decides to give you a ring.

Not really in the engineering tolerance you wanna be to stay alive,
particularly with how wildly variable the resistance estimate can be,
and the variability of what level of macroshock is needed to cause the
heart muscle to fibrillate.

Throw $15 at a cordless phone. :-)


Best Regards,
--
Todd H.
http://www.toddh.net/