"Robert11" wrote:
Have been trying to get some smoke detectors interconnected, and
during the trouble shooting of the problem, I measured (with an analog
voltmeter) the
voltage between the white neutral, and the bare copper ground wire in the
box.

Was very surprised to see that it was about 2 V AC.

Other than the fairly obvious reasons, such as bad ground connections in the
service box for the neutral or gnd, or within the wiring chain itself, was
wondering if anyone might have any other thoughts or opinions on this.

Might as well add this: The smoke detectors were on line, and functioning,
when I measured.
The interconnect for the smoke detectors (the third, red, wire ) uses the
white neutral (also)
as it's return. And, measuring a few outlets around the house showed 0
voltage between the neutral and gnd as one would expect.

But, even if the smokes were dumping something on the white neutral, it
being at gnd potential, would "sink" these voltages immediately, I would
think, if the neutral was grounded well.
So, what might be happening ?

BTW: How "common" is it to see voltages of this magnitude between the white
neutral and ground ?

If you have a large load upstream from the smokes on the circuit, it's possible
to get a couple of volts on the neutral relative to ground. In that case, no
big.

However, if the smoke detectors are on their own circuit, or you don't have a
large load on the circuit, then you've got a loose splice on the neutral
somewhere between the measurement point and the grounding bar in the breaker
box. Not quite a floating neutral, but thinking about it. Real fun to track
down, especially since you usually don't know the wire routing.