cloudymacleod
Senior Member
is it possible to wire a 3 way with out the switch leg?
3 way without a switch leg
- Thread starter cloudymacleod
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ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 3 way without a switch leg
If you don't want the light to turn on.
If you don't want the light to turn on.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way without a switch leg
An old K&T threeway switch setup that I have seen occasionally for the main stair luminaire of classic two story single family dwellings will put a hot and a neutral on each of the switch traveller terminals. Occasionally, the upstairs hot and neutral will even be on a different circuit than the downstairs hot and neutral (although they are always on the same bus in the panel).
The common terminal of each threeway switch will have one wire running to the luminaire.
In operation, the polarity in the lampholder of the luminaire will reverse, depending upon switch positions.
Each wire attached to the lampholder may either be a grounded conductor or a switched hot OR both conductors may be hot conductors or grounded conductors.
So,
In two (the OFF state) of four possible switch states, the threeway setup has no switched leg.
An old K&T threeway switch setup that I have seen occasionally for the main stair luminaire of classic two story single family dwellings will put a hot and a neutral on each of the switch traveller terminals. Occasionally, the upstairs hot and neutral will even be on a different circuit than the downstairs hot and neutral (although they are always on the same bus in the panel).
The common terminal of each threeway switch will have one wire running to the luminaire.
In operation, the polarity in the lampholder of the luminaire will reverse, depending upon switch positions.
Each wire attached to the lampholder may either be a grounded conductor or a switched hot OR both conductors may be hot conductors or grounded conductors.
So,
In two (the OFF state) of four possible switch states, the threeway setup has no switched leg.
cloudymacleod
Senior Member
Re: 3 way without a switch leg
well, here is the reason i ask. is that an issue i came across was a 3 gang box w/3 switches, all on the same circuit, its a split house by the way. one 3 way controls the light in the down stairs foyer. that 3g box has the feed going into that box. the travling wires go from the 3g box to the light, in the light there is another set of travling wire going down to the other 3 way controlling this light. in that switch box its the sole set of wires, so its almost acting as a dead end 3 way but the white wire is not commen, the black wire is. In the light box, the red r spiced, the white wire from the single gang is spiced with the black wire coming in from the 3 gang, with the neutral coming from the 3-gang tied to light itself. the black wire from the single gang is also tied to the light. the 3way switch in the 3 gang is wired as a regular 3 way with the neutrals spiced together, the traveling black and reds r on the right terminals and the feed is your common(point). so the light is getting its neutrals but how is get electricity to the light. The 3ways work like the should work.
well, here is the reason i ask. is that an issue i came across was a 3 gang box w/3 switches, all on the same circuit, its a split house by the way. one 3 way controls the light in the down stairs foyer. that 3g box has the feed going into that box. the travling wires go from the 3g box to the light, in the light there is another set of travling wire going down to the other 3 way controlling this light. in that switch box its the sole set of wires, so its almost acting as a dead end 3 way but the white wire is not commen, the black wire is. In the light box, the red r spiced, the white wire from the single gang is spiced with the black wire coming in from the 3 gang, with the neutral coming from the 3-gang tied to light itself. the black wire from the single gang is also tied to the light. the 3way switch in the 3 gang is wired as a regular 3 way with the neutrals spiced together, the traveling black and reds r on the right terminals and the feed is your common(point). so the light is getting its neutrals but how is get electricity to the light. The 3ways work like the should work.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way without a switch leg
This is a regular setup.
One traveller changes color from black to white. That's all.
The black between the lamp and the single gang is the switch leg.
This is a regular setup.
One traveller changes color from black to white. That's all.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way without a switch leg
Ahhh.
It just occured to me that you may be thinking of the cable as the switch leg. The switch leg is the conductor that connects to the hot side of the lampholder.
Ahhh.
It just occured to me that you may be thinking of the cable as the switch leg. The switch leg is the conductor that connects to the hot side of the lampholder.
cloudymacleod
Senior Member
Re: 3 way without a switch leg
thanks, i get it know, the black travler from 3g just gets tossed to the white wire in light box, know in turn acts as the travler oppisite of the red wire to the single gang, and the black wire acts as the sw/leg. know do u think that wireing precdure saves money and time from running a 2-wire from the single gang to the light and not running the travlers str8 to the 3gang to the sing gng
thanks, i get it know, the black travler from 3g just gets tossed to the white wire in light box, know in turn acts as the travler oppisite of the red wire to the single gang, and the black wire acts as the sw/leg. know do u think that wireing precdure saves money and time from running a 2-wire from the single gang to the light and not running the travlers str8 to the 3gang to the sing gng
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way without a switch leg
To me, it depends on the situation. I rarely use it. But I have used it.
To me, it depends on the situation. I rarely use it. But I have used it.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: 3 way without a switch leg
I tend to use it on the basement stairs threeway, if at all. In the model I'm thinking of, there is a huge lam running around the staircase, and an I-Beam directly below the threeway at the top of the stairs. So, the most convenient route is to the top of the stairs is through the wall, right past the light.
However, if it takes as much time or more to strip out the light with three cables or more, I run a two-wire switchleg.
Using the "crimp" identification method, I crimp the two cables in the light thusly, so they don't get confused:
X = Travellers from the power side of threeway
XI = Travellers going to the dead-end threeway (Black wire is switchleg)
Generally speaking, keeping it simple saves the day. But on occasion, it's good to have a trick in you sleeve.
I agree with Al.
I tend to use it on the basement stairs threeway, if at all. In the model I'm thinking of, there is a huge lam running around the staircase, and an I-Beam directly below the threeway at the top of the stairs. So, the most convenient route is to the top of the stairs is through the wall, right past the light.
However, if it takes as much time or more to strip out the light with three cables or more, I run a two-wire switchleg.
Using the "crimp" identification method, I crimp the two cables in the light thusly, so they don't get confused:
X = Travellers from the power side of threeway
XI = Travellers going to the dead-end threeway (Black wire is switchleg)
Generally speaking, keeping it simple saves the day. But on occasion, it's good to have a trick in you sleeve.
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