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. :-)
Here the line has 50VDC when not in use. When ringing it has both
50VDC and 75VAC on it (alternating between -25V and +125V, I think at
20Hz). Ringing current capability is significant, since it's intended
to ring 5 loud bells.
Very bad idea. Ringdown voltage is near or exceeding wall outlet
voltage. Granted, current capability is lower, but it's
enough.... and the the human body's resistance while soaking in water
is quite low.
Cordless phones are cheap. You need one if you wanna chat in the
I have a phone jack next to my bathtub. I only plug in a handset
(which has to be rewired iirc to use it this way, and it worked better
when I put on a wider plug than handsets have). I don't place calls
because there is no dial, and I answer the phone between rings. I
also don't let the phone get wet, and if my hand is wet, I think I
wipe it off with a towel.
I also do the same thing before I adjust the volume on the tv. The tv
has a sound output, and I have a cord coming out of the wall behind
the tv, speakers from a 1950's Hi-Fi on the ceiling, and a volume
control next to my shoulder on the bathroom wall. That way I can turn
the volume down when I'm on the phone. I also tied a washcloth (and
later I changed it to a sock) so the water doesn't make much noise
when it runs into the tub. That way I can also keep a trickle of warm
water coming in so the bath doesn 't get cold.
They're nice to have if (like me) you occasionally have to attend
long-distance training courses and are on a conference call for 7 hrs
Or during a power outage. (I know they make cordless phones with a
second battery in the base for just this scenario, but they aren't very
Just so y'all know, if you call me it better be because you need an
organ donor because you had a pneumatic nailer mishap or someone in my
family died.... and you'd better not ever, under any circumstances,
call me from a hot tub.
I suggest you buy the manliest looking phone you can find...that way if
you do drop the beast into the tub, the newspaper article will at least
say you died at the hands of a red sox phone.
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