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Posted by John Grabowski on October 4, 2007, 7:38 am
> On Thu, 04 Oct 2007 06:18:23 GMT, Noozer wrote:
>
> > The black is always on and is the power. The white is what is switched
on
> > and off and is the load. You're missing the needed neutral. You should
also
> > have a bare copper wire, which is ground. This is because the switch
comes
> > AFTER the light in your circuit instead of before it.
>
> Thank you Noozer for your volunteer help; I greatly appreciate the advice.
> I'm a bit confused. If a circuit is a complete loop, why would it matter
if
> the switch is before or after the load?
>
> Note: I do understand that the black wire in the wall is the hot (incoming
> 120vac) wire and that the white wires in the wall are the neutral
> (outgoing, supposedly near 0vac) wires which go into the ground at every
> fifth telephone pole or so. And I do understand that the bare wire (green
> on the switch) is grounded to my water pipes and does not carry current
> normally. But I have no idea what this red (load) wire is supposed to do.
>
> In looking again, there is a bare copper wire inside the box as you noted,
> so you know your stuff. But there certainly isn't a red wire.
>
> While I understand your basic premise that I can't use the switch because
I
> don't have three wires in the box (black, white, red) to connect the three
> wires on the switch (black, white, red), I still don't understand why this
> circuit is different.
>
> If it helps, I did put the switch on another wall outlet which did have a
> black, a set of whites crimped together, and a red ... and the Legrand
> "WattStopper RS-150BA-N Vacancy Sensor Switch with Nightlight and Manual
> on/off" wall switch worked fine.
>
> Can you explain why some of my wall boxes have only a black and a white
and
> ground while other boxes have a black, a set of whites crimped together,
> and a red wire?
If the switch was wired according to generally accepted practices, the white
wire is probably the hot and the black wire is the load. A simple bulb and
pigtail socket can confirm this. Check each wire to ground. You need a
neutral to operate the WattStopper just like you need a neutral to operate
the light fixture. You do not have a neutral so you cannot use the
WattStopper to replace this switch. The alternative is to rewire the switch
with a three wire cable from the ceiling light.
In this case the original installer found it easiest to just run a switch
leg to the wall switch from the ceiling light to interrupt current going to
the light fixture. If you were to remove the light fixture and look in the
ceiling box you may see that the white wire from the switch is connected to
a black hot wire and tucked into the back of the box. You should also see
the black wire from the switch connected to the light fixture and a white
neutral wire connected to the light fixture as well.
Other wall boxes may have more wires in them because the original installer
chose to use them as junction boxes to make splices so that other outlets,
switches, or lights can be fed from those particular locations. Either way
is acceptable. Lately I have been running my feeds through the switch box
because of instances such as yours when a neutral is required.
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