On Sat, 21 Nov 2009 13:33:28 -0800, David Nebenzahl
wrote:

On 11/21/2009 12:19 PM Higgs Boson spake thus:

On Nov 21, 12:06 pm, David Nebenzahl wrote:
On 11/21/2009 11:51 AM Higgs Boson spake thus:

Am about to replace hideous doorbell. AFAIK, I just have to unscrew
tthe old one and attach the new one to the wires.
BUT - how do I know which "breaker" as they used to call them,

Still do.

controls the doorbell? I looked in my switch box, where I have
everything labeled, but did not see "doorbell". It rings in the
kitchen. Anybody hazard a guess where it might be connected?

Could be on any breaker; no official rule for where to put a doorbell.

Probably several ways to skin this cat. One would be to put a voltmeter
on the transformer (that's the thing that supplies low voltage
power--typically 16-24 volts--to the actual doorbell) and flip breakers
until it goes to zero volts (assuming the transformer works). Probably
the safest way; that secondary (low-voltage) side of the transformer
isn't going to hurt you if you get shocked by it.

Friend told me that if I just touch one wire at a time, I won't get
shocked.
T/F? Makes sense ; circuit not completed; but hard to isolate wires
in small space.

Welllll, that's true in *theory*. But probably lots of folks have been
hurt (or even killed) when theoretically impossible.

Just to be clear, there are two issues he

1. Whether or not you can get shocked by just touching one wire of a
circuit.
2. Low voltage vs. high voltage.

First issue: yes, in theory if you touch only the hot wire of a circuit,
you won't get shocked. (Works for birds sitting on powerline wires, for
instance). Problem is there are other sneaky way of the circuit
completing itself, like through damp ground, your shoes and your feet.
So the best policy is to never touch *any* wires (energized ones, that is).

Second issue: As I said, doorbells operate on low voltage (somewhere in
the range of 12 to 24 volts AC). Getting shocked by such low voltages is
a lot safer than high voltage (like the 120 volts in your household
wiring). While it is theoretically possible to get electrocuted from
even a low-voltage shock, it's unlikely. So it's safer messing around
with low-voltage wiring that may be live than high-voltage wiring. Still
not recommended (see best policy above).

I cannot recall the exact details, but I'm sure it had to do with
moisture. Working on a 12V truck battery, I got "bit". Not sure what
was touched by the tools or the wetness and leaning against the truck
fender.

I was "shocked" it could happen. Hasn't happened since.