3 way switch -common connection ?
#1
03-27-16, 10:18 PM
3 way switch -common connection ?
Hi - I am replacing a 3 way switch with an electronic switch with a motion detector. The wiring instructions show that you leave the other mechanical switch in place and make a few modifications to its wiring. All of the wring makes sense to me except for one small part. The thing that seems odd is that the remaining mechanical switch has a wire going from the common to what seems to be a completely unused non-common terminal. Wiring the common to a non-common terminal just seems redundant. Can you think of a reason? I know electrical codes can be weird sometimes, so maybe there is a code where you can't leave terminals unused?
Here is the diagram:
Here is the diagram:
#2
03-27-16, 10:34 PM
Your only using the mechanical switch to send a signal to the electronic switch. The signal is the momentary interruption of power when the mechanical switch is switched. That signal tells the electronic switch to change states, either from closed to open or open to close. Or that's my guess and I'm sticking to it til Pete corrects me.
#3
03-28-16, 01:21 AM
Group Moderator
Sounds like a valid reason Ray.
Usually only one traveler is used from the existing three way switch but things are always changing. Without the model number of the switch.... can't be of much more help.
Usually only one traveler is used from the existing three way switch but things are always changing. Without the model number of the switch.... can't be of much more help.
#4
03-28-16, 09:15 AM
Your only using the mechanical switch to send a signal to the electronic switch. The signal is the momentary interruption of power when the mechanical switch is switched. That signal tells the electronic switch to change states, either from closed to open or open to close.
The switch is a Leviton IPS06.
#5
03-28-16, 11:53 AM
Group Moderator
I was looking further into that control. That one does use strange wiring when compared to the single pole connections.
The sensor is always powered thru the red wire that comes from the standard 3w switch.
In one direction there is no power on the 3w/brass connection and in the other position there is power on the 3w/brass connection.
The sensor is always powered thru the red wire that comes from the standard 3w switch.
In one direction there is no power on the 3w/brass connection and in the other position there is power on the 3w/brass connection.
#6
03-28-16, 12:39 PM
The sensor is always powered thru the red wire that comes from the standard 3w switch.
In one direction there is no power on the 3w/brass connection and in the other position there is power on the 3w/brass connection.
In one direction there is no power on the 3w/brass connection and in the other position there is power on the 3w/brass connection.
It's not a big deal, I can either connect it or leave it disconnected (it is the same either way). Just curious.
#7
03-28-16, 12:53 PM
Group Moderator
Yes..... you probably don't need to bridge common to one traveler.
All the occupancy sensor is looking for from that switch is power on or power off to the 3w/brass terminal. Technically you could change the three way switch to a standard switch and it would still work.
All the occupancy sensor is looking for from that switch is power on or power off to the 3w/brass terminal. Technically you could change the three way switch to a standard switch and it would still work.
Last edited by PJmax; 03-28-16 at 04:22 PM. Reason: typo
#8
03-28-16, 01:46 PM
Yes..... you probably don't need to bridge common to one traveler.
It saves me from a big ugly 4 wire marette connector and an extra pigtail (hard-nuff to fit things into the box as it is).
I just mocked-it-up on the bench and (as expected) it works the same either way.
The only thing I can figure is that they just don't want homeowners getting freaked-out as to why there is an empty terminal, so they just connect it "something".
