On Feb 10, 11:17 am, terry wrote:
On Feb 10, 9:40 pm, BobK207 wrote:
On Feb 10, 7:42 am, Doug wrote:
Replacing a single light fixture that's controlled with two switches.
The light box has a standard black/white/ground supply wire. While
installing I found that the white wire was actually hot (and marked
with black tape) and the black was neutral. The only issue was the
only way I could read 120V from the hot wire was to ground the
circuit. This seems odd to me as none of the three way wiring
diagrams I've seen seem to require the neutral being grounded at the
fixture. The reading from hot to neutral was 60V - not sure if this
means anything or not.
Is this OK or is there something I need to look into here?
Thanks
Doug
Doug-
IMO you need to look into this a little.
The wring to the first switch box should be an un-switched hot
(black), an un-switched neutral (white) & a ground wire to the switch
& the box (if metal) .
The wiring from the first switch box to the second switch box should
be two switched hots (black & red or re-indentifed white), an un-
switched neutral (white) & a ground wire to the switch & the box (if
metal) .
So one needs 4 conductors (including the ground) between the two
switch boxes....here's where some people either get confused or
cheat. Ideally you use a three wire romex (black, red, white,
ground) or a double run of 2 wire Romex.
From the second switch box to the fixture box you should have a
switched hot (black), an un-switched neutral (white) & a ground wire
to the switch & the box (if metal) .
The setup you describe (if I'm understanding it) seems a little
off.
Is the circuit wired with Romex or single conductors (knob & tube OR
wire in conduit)?
Maybe the circuit existed as a single switch & the three way part was
added later.
Be careful, because of the limitations of 2 wire Romex systems, some
people take shortcuts on rewiring or additions that can leave you with
less than safe situations.
per John's comments a light bulb is often better than a meter
The 60v reading might be a result of a poor connection somewhere or a
digital meter giving a false reading reading.
cheers
Bob
Bob that info 'could' be misleading?
What it sound like, as mentioned in one of the replies is that black
and white wires go from the ceiling box down to the switch. One of the
wires is the 'live' feed in and the other is the 'switched live'.
Consequently when the switch is 'on' electricity flows down to the
switch through the switch and back up to the 'hot' side of the light
fixture; and the light goes on.
Reading 60 volts may be meaningless; even cheap modern digital meters
can pick up voltages due to capacitance between wires etc. A much
better way to test is to use a regular bulb.
Nothing should be wired to the ground except metal parts of wiring
boxes, ceiling boxes, metal roses etc. the ground is a safety wire.
The ground can, but only 'momentarily' be used for testing; for
example put the test bulb between a wire and ground; if it comes on
all the time (with circuit breaker for that circuit on) it is a 'non-
switched live'. If it goes on and off as you operate the switch it is
a 'switched live'.
Then turn off the circuit breaker and wire the switched live to the
light fixture (or fixtures. Cos some rooms have two or more lights
controlled by the one switch!) Turn breaker back on (or reinsert
fuse) and test.
Terry-
I composed a reply to your comments but lost it when my PC froze.
I'm pretty sure from Doug's original post there is only a white
(tagged with black) & a black wire in the fixture box under
consideration.
If Doug's only got two wires in the box & the tagged white is hot (&
switched)
and the black wire is in fact the neutral (0 volts to ground) ...then
he's got some color coding issues.
I'm not sure I'm understanding your comment
What it sound like, as mentioned in one of the replies is that black
and white wires go from the ceiling box down to the switch. One of the
wires is the 'live' feed in and the other is the 'switched live'.
Consequently when the switch is 'on' electricity flows down to the
switch through the switch and back up to the 'hot' side of the light
fixture; and the light goes on.
if he's only got two wires and one goes to the switch & the other
comes back....he's got no hot feed & no neutral. ???
It seems to me for a switch leg to exist he'd need four wires in the
box; hot in, hot to switch, switched hot back from switch & of course
the neutral.
We'll see what Doug discovers & reports back.
cheers
Bob