3-way switch illuminated when off??

[Lord Garth]

3 way switches have 3 terminals: a common and two non common. The
common is wired to the load or to the hot. The two non commons are
wired between the 2 switches via two wires, usually black and red. When
the load is activated there is no potential between the common and non
common 1 (shorted) or non common 2 (no connection), nor between the two
non commons 1&2 (one is active the other no connection) When the load
is off a potential appears between the two non commons 1&2 since one
will carry the hot and the other will be connected to neutral through
the load.
The neon and series resistor will be connected between non common 1&2.
Typically they draw .5 to 3 ma so when you connected your meter it
caused the neon to light but dimly. The resistor is usually 19k to
220k.
Richard

You're describing exactly what I drew...I just don't know what kind of a
load
a DMM set to volts and placed in series does W.R.T. the neons. I not going
to test it either!!!!

 

[Chris]

You're describing exactly what I drew...I just don't know what kind of a
load
a DMM set to volts and placed in series does W.R.T. the neons. I not going
to test it either!!!!

Why not? If measuring voltage the input impedance of a DMM would be fairly
high - into the Mohms, I would suggest - subject to range selected.

Cheers.

 

[Lord Garth]

Why not? If measuring voltage the input impedance of a DMM would be fairly
high - into the Mohms, I would suggest - subject to range selected.

I'm not that curious since I can see it's wrong. I might use a high value
resistor
though, just not my DMM.

 

[js5895]

Well I don't want you people hacking up your stuff or hurting your
selves,
just so I can see how something works. I herd of horror stories of,
meters blowing up because of high voltage or the meter not
being on the right setting, scary. I have a Fluke T5-600 and a
cheap $10 DMM, any time I mess around with 120VAC or
higher, I use the Fluke. In my picture, I did connect my meter in
series with the switch, I connected the meter to the screw that
was switched off and, in setup A the neon glowed very bright like,
a small night light and flickering like a candle flame but, in setup B
very dim, couldn't even see it, and like I said earlier, I connected
the meter to the line and then to one screw and it lit?. The reason
why I wanted to know how it works is because, until a week ago, I
didn't even know these switches existed because, I know pilot
switches have a neutral for return and they function when there
turned on but, this is totally opposite, and wouldn't something in
series
would make the bulb lose voltage.

Thanks.

 

[John G]

Hey thanks, that little arrow help a bunch. No, I can't tell you why
it
lit the neon at all, I'll just have to waste one! Have Dremel, will
travel.
Remember that voltage is read across a circuit or device, not in
series.
Please don't read current when your testing mains unless you get a
clamp
on probe. I'm glad you and the meter are okay!

There are neon testers around which have a neon and resister inside a
screwdriver handle and a metal contact at the end of the handle.
If the blade is on a hot wire then the neon will light if you put your
finger on the other end.
The circuit is completed by the capacitive coupling of your body to the
general ground which of course is at the same potential as the neutral.

 

[js5895]

Cool I like that tester. It just hit me to go to the manufactures site,
hello?,
and I found a wiring diagram of how it works, I had a hard time reading
those ACSII diagrams, you guys were right, see:
http://www.levitonhelpdesk.com/catalog/images/wd3wlh.jpg

Thank you, for all your help.