Re: 3-way switch illuminated when off??

On Sun, 17 Apr 2005 10:14:38 -0700, js5895 wrote:

> I tried connecting a meter, in voltage mode, and it acted weird see:
> http://home.nycap.rr.com/joshs/threewaywire.bmp
> I also connected the meter to the line, and just one screw and it
> lit!!, but very dimly.
>
> Thanks.

Are you saying that the switch itself is illuminated, or that the lamp
plugged into the switch is illuminated? I have a wall switch that is
lighted, in which the light is on when the switch is off.

However is there is a short through the switch, you should replace it.
Sadly, I had trouble interpreting your picture.

For a three way switch, you have this situation:
{view with fixed-point font)

S1
line --[lamp]--o o---------------------oo
\ \
\ \
oo---------------------o o---- neutral
S2

Thus, either of the switches can light the lamp.

If one of the switches has failed such that it is closed on both paths,
or if the wiring is broken in this way, it'll light in either
position. So, for example, if S2 has a path like this:

S1
line --[lamp]--o o---------------------oo
\ \
\ \
oo---------------------oxxxxxxo---- neutral
S2

Then even if the xxxxx path is fairly high resistance, the lamp may
act like you are describing. You can test this by disconnecting
neutral from S2, and line from S1 and testing the resistance between
the two throws of S1. If it is less than 10MEG, you have trouble.

Note that the lamp may be in a different place; thus, I wouldn't trust
that pulling the lamp will disconnect you from line.

----
Regards,
Bob Monsen

.

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