On Tue, 10 Jan 2012 07:29:56 -0800 (PST), "
wrote:

On Jan 9, 5:07Â*pm, wrote:

Ok, let's work with basic electrical theory. Â*The chime
is wired with Â*a two conductor cable. Â*Place a short
in that cable anywhere along it's run and you will
still have sparks when you short the door switch
wires and no power at the chime. Â*Is that more
likely than the door chime being the culprit? Â*No
and I already agreed the chime should be
investigated next. Â* But you can't rule out a short
along the way either. Â*It's easy to test for power at
the chime with the door switch shorted and that's
what I would do. Â*If he doesn't have a tester and
doesn't want to spend $10 on one, then he can
skip that step.

Â*Draw out the circuit. Â*2 options. Transformer to bell to button, or
transformer to button to bell.


I don't need to draw out the circuit. The chime is a
2 wire device. A 2 wired cable is frequently used to
connect to it. That wire runs some length through
the house, often to the transformer, where one
wire connects to the transformer, the other to one
wire going to the door bell button. The doorbell
button is another 2 wire device. It frequently is
wired with a 2 wire cable back to the transformer
where one wire gets connected to the other side
of the transformer, completing the circuit.
Doesn't get any simpler than that.


Except up here I've NEVER seen it done that way.
Always 2 wire from trans to chime, and 2 wire to each button.
Now let's say the chime is OK. The 2 wire cable
connected to it as described above is however
shorted somewhere along it's run between the
transformer and the chime. You touch
the doorbell wires together and you get sparks.

That would happen, but it would not be wired according to the
instructions with the chime, which, almost universally, has a common
(or T for Trans) F (or S) and R connection, and sometimes a 4th
connection to act as a Return, where the second wire from each button,
and the second wire from the transformer, all join instead of using a
wire-nut.




That's why I suggested that he listen for a hum
at the chime or test for power at
the chime with the doorbell wires connected. It
quickly rules out the possibility of a short.

And if there is power at the chime without pressing the button, from
the T to the wire nutted return, he knows it was not "misswired" and
there is no short.