On Dec 9, 7:24*pm, John Fields wrote:
On Tue, 9 Dec 2008 15:22:26 -0800 (PST), bandito



wrote:
On Dec 8, 6:53*pm, JeffM wrote:
bandito wrote:
[...]If I held the door bell transformer[,]
the noise would diminish although still evident.
Since the door bell is not being used[,]
I disconnected the black wire that came from the breaker
I had just replaced, put a marret on it and the noise stopped.
My question is, is this sufficient and safe

Yup.
One hopes you did this where it is evident and easily accessible
(and that you left a note in the panel
for the next poor sap that has to work on things).

or should I also disconnect the white wire
that is connecting to the bar above the breakers?

Nope.

When you have a question about transistorized gear,
_that_ would be "electronic";
*electrical* (house) wiring is discussed in
alt.engineering.electrical and alt.home.repair.

Just out of curiosity, why is it ok to disconnect the black wire and
not the white wire??

---
According to US code, the black wire is 'hot' and is the voltage source,
(black being the color of death) while white is the return, and should
be close to zero volts, always.

If you disconnect the white wire from the primary of the transformer,
the earth connection will be broken and charge will no longer flow in
the primary, which will result in no output from the secondary.

However, the voltage source will still be connected to the primary,
which could lead to disastrous circumstances if one thought it was safe
to muck about in the equipment after the humming stopped.

JF *

I think I got it. So if the black was connected and the white was not
there would still be power in the transformer and someone could get
hurt if they touch the transformer the wrong way however if the black
is disconnected and the white is still connected any charge would
travel down the white wire making it safe.

Makes practical sense.