3 way switching

Merry Christmas
Status
Not open for further replies.

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
For excellent interactive switch and lighting circuits visit Member Ronald Colemans Page and while you're there spend some time on his other links

Here' a Tennessee Threeway

at.gif



Roger
 
Last edited:

kwired

Electron manager
Location
NE Nebraska
The problem with the so-called California threeway shown in this diagram occurs when one uses the lower traveler (the always hot traveler) to supply downstream load.

When both switches are off and in the "down" position, any load downstream of the right hand threeway will have its load current split between the lower traveler and the common to common conductor. This is a parallel installation and the conductors are smaller than the 1/0 allowed in 310.10(H).

It is nice you caught that potential problem, I only ask we do not turn this thread into the same debate about whether or not this is a parallel circuit that is prohibited by code currently going on in a couple other threads. It is debatable whether or not that is compliant or not based on information in those threads, and was topic of a long thread some time ago also. Search for the term "ring circuit and you will likely find these threads, and maybe some others I was not aware of.

For excellent interactive switch and lighting circuits visit Member Ronald Colemans Page and while you're there spend some time on his other links

Here' a Tennessee Threeway

at.gif



Roger

Appears to be pretty easy to add additional switch locations if desired.
 

LEO2854

Esteemed Member
Location
Ma
It is nice you caught that potential problem, I only ask we do not turn this thread into the same debate about whether or not this is a parallel circuit that is prohibited by code currently going on in a couple other threads. It is debatable whether or not that is compliant or not based on information in those threads, and was topic of a long thread some time ago also. Search for the term "ring circuit and you will likely find these threads, and maybe some others I was not aware of.



Appears to be pretty easy to add additional switch locations if desired.
Would the next location be called a 4-way?:lol:
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Gee Thanks Roger now everyone on here knows Tn. is still in the stone age.:happysad:

Ronald :)

Well, you could show them the hospital version, the one where the strings are fed through EMT. :D


Roger
 

John120/240

Senior Member
Location
Olathe, Kansas
Maybe Ron says this, but I believe that his 3-way switching circuits numbers 9 and 10 are non-compliant with the 2011 NEC, because neutral is not present at switches controlling lighting.


Ron put his diagrams up before the neutral requirement came in effect. They are an excellent tutorial on how three way switching

works. Studying Ron's diagrams will give the inexperienced hand a visual understanding of how wiring works.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Ron put his diagrams up before the neutral requirement came in effect. They are an excellent tutorial on how three way switching

works. Studying Ron's diagrams will give the inexperienced hand a visual understanding of how wiring works.

I agree and if he edited them to show EMT or conduit in place of the NM they would be good to go even under the 2011.


Roger
 

ronaldrc

Senior Member
Location
Tennessee
It is nice you caught that potential problem, I only ask we do not turn this thread into the same debate about whether or not this is a parallel circuit that is prohibited by code currently going on in a couple other threads. It is debatable whether or not that is compliant or not based on information in those threads, and was topic of a long thread some time ago also. Search for the term "ring circuit and you will likely find these threads, and maybe some others I was not aware of.



Appears to be pretty easy to add additional switch locations if desired.

Haven't been on the computer for a day or two.

Thanks for the compliments on the switch diagrams.

I'll not add a neutral to my diagrams. :roll: , Although I have forgotten most of it, if they are a certified
Electricians they should know their code.


Al

It has always been my personnel belief that the Code section on paralleling conductors
was put in the code just to keep some Electrical installers from paralleling small conductors such as
#14, 10 conductors to make 30 and 60 ampere feeders.

I was once ask on a residential job to pull two 10/3 nms to a range rather than go to the hardware
and pick up roll of 6/3 cable. I was just a helper at that time but I knew the Electrical inspector wouldn't
pass it and told my boss I wouldn't do it, he didnt like it but he knew I was right.

Some contractors will try anything to same a buck.


This is my final say on this paralleling bit.

Ronald :)
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
. . . his 3-way switching circuits numbers 9 and 10 are non-compliant with the 2011 NEC . . .
More than the 2011 NEC is in play. As an example, take a closer look at #4, the so-called Chicago Threeway. The polarity of the lampholder changes, depending upon switch position. That has not been "compliant" with the NEC since back in the Twenties.

But, if you've ever worked on a wiring installation from before the required polarity of the lampholder went into effect, knowing that such a thing could exist will greatly de-mystify the initial troubleshooting. You will also be able to serve your customer better for the knowledge.

I live in an area that has a good number of single family two story dwellings built before 1920. Most of these were originally wired with Knob and Tube, and have a light over the main stairwell that is controlled by a pair of threeway switches. That threeway stands an excellent chance of, not only, being a Chicago threeway, but also a Chicago threeway installed between the upstairs circuit and the downstairs circuit. Now. . . imagine doing a simple panel changeout / service upgrade, and, without anticipating this, you put those two original K&T circuits on opposite buses. . . .

Ronald's animated switching diagrams communicate, in a short space of time, what static diagrams would have you wade through in pages of print to understand. And they are a treasure trove of the kind of installations one will find out in the "wild" including the Tennessee threeway. :cool:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Al

It has always been my personnel belief that the Code section on paralleling conductors
was put in the code just to keep some Electrical installers from paralleling small conductors such as
#14, 10 conductors to make 30 and 60 ampere feeders.

I was once ask on a residential job to pull two 10/3 nms to a range rather than go to the hardware
and pick up roll of 6/3 cable. I was just a helper at that time but I knew the Electrical inspector wouldn't
pass it and told my boss I wouldn't do it, he didnt like it but he knew I was right.

Some contractors will try anything to same a buck.


This is my final say on this paralleling bit.

Ronald :)
Thanks Ronald,

I whole heartedly agree with you. I've been fortunate not to have a boss direct me to do such a thing.

I did spend some time going through the threads Kwired refers to and I still find 310.10(H) applies to the OP's circuit when there is downstream load. Just my opinion.
 

RustyShackleford

Senior Member
Location
NC
I certainly had no intention to harsh on Ron. They are great diagrams. And useful for understanding what might have been done on existing work. And with any luck, the next code cycle will add more amendments to 404.2c to remove the neutral requirement for places where it doesn't seem to make sense, like indoor switches controlling outdoor floodlights (unless there are reasons other than an occupancy sensor switch).
 

ronaldrc

Senior Member
Location
Tennessee
I was thinking something even more primitive would be the "normal":D

like the knob that you turn to move the wick up or down on an oil lamp:lol:

Ah:

That brings back old memories as a young boy growing up in the late 40s and
early fifties I remember watching our scanning disk machine by candle lite. :lol:

Rusty" Thanks
Anyway in my examples if you read close enough I tell how the Chicago Threeway
is a illegal install today.

And talk about how hard it would be to troubleshoot the california threeway.
I would never use it or recommend it.

I don't even know if anyone ever used the fourway, I never have. After Al Hildenbrand posted the version
he had seen somewhere. Well I just had to add a fourway. Al originally posted this picture
several years ago.



First time I believe any of us had ever seen it. I have forgotten where Al said he seen it?


Heres Als original drawing.

Al hildbrand.jpg



Ronald :)
 
Status
Not open for further replies.
Top