California or Chicago?

[Woodyz]

Sorry to beat a dead horse. I can't seam to get a handle on the California 3 way. I have ran into the Chicago before. Feel sorry for those who have ran into it with no prior knowledge of them as I did.

I've read many discussions on the subject, but the Cal. is out of my mental capacity.

Anyone have a diagram?

 

[George Stolz]

Re: California or Chicago?

Try to avoid using it. It's good to know how to do, but if you screw it up, you'll shoot your labor fixing it.

Also, more importantly, the EMF from the uncancelled conductors that are part of the California threeway, can screw up computer monitors. The EMF also has the reputation of causing leukemia in children.

 

[hurk27]

Re: California or Chicago?

I thought that Chicago and California three-way was the same just different names? (I can't remember)
Some even called it a KT three-way or a barn three-way as this was what it was used for most. It provided the hot/neutral for receptacles, via the travelers and the third conductor was used to switch a light at both locations. The problem is with every other change of the switch's the lamp socket would change polarity, which is a violation of the NEC. These were very common on K&T jobs between the floors on stairs, and between the house and barn/garage.

Do a search on here and you should find several threads that have a diagram on how there switched.

Edited because I can't spell ether. Smile Sam

[ May 09, 2005, 10:19 PM: Message edited by: hurk27 ]

 

[paul]

Re: California or Chicago?

I thought this was a CA 3-way done with knob and tube wiring.

 

[Woodyz]

Re: California or Chicago?

George,

Your drawing is still unclear to me. It doesn't show any physical connections i.e. where the wires are on the switches.

I have no intention of using it. Just wanted to be prepared if I ever happened to run into it on a job.

Paul,

Your picture shows what I've been referring to as a Chicago. If that is also a California that would end alot of my confusion.

 

[paul]

Re: California or Chicago?

Is this, then, a CA three way??

 

[George Stolz]

Re: California or Chicago?

Paul's (edit: first) picture is displaying what I would call a "Chicago" threeway. You'll notice the neutral is used in the switching, which is illegal by Article 404.

The smaller pictures to the bottom of the whole picture are details of the boxes.

On the power side, the power is the common, and you have two-wire travellers between switches. (Otherwise, you'd have three-wire running between threeways, right?)

On the switchleg side of the threeway system, you have a dilemma. Since you only have two travellers with no neutral, you have no source of neutral. Therefore, you would have to steal a neutral from somewhere else.

In the picture above, I have pulled power around the room for receptacles, and ended up in the "Switchleg" box with power. Since the supply for the threeway is on the same circuit, it works. If you try to steal a neutral from a different circuit on the same phase, backfeeding may occur. Stealing from another circuit from a different phase could cause backfeeding when the switch is off, maybe. I think I've run into that before.

Notice, you're not switching a neutral with a California threeway. The white wire is ungrounded, and needs to be reidentified per 200.7(C)(2).

Hope that helps.

[ May 10, 2005, 12:03 AM: Message edited by: georgestolz ]

 

[George Stolz]

Re: California or Chicago?

Realize, we're talking slang, so some folk's slang will be different.

Paul, the travelling bus threeway turns threeway switching on it's head: the commons are tied together.

The California threeway uses normal switching technique: A power common on the first end of the switching system, and a switchleg common on the last end of the switching system. The only peculiarity to the CA S3 is the fact that the neutral is not carried with the travellers.

 

[paul]

Re: California or Chicago?

I think I'll just stick to the standard way of 3-way switching, since I'm neither in CA or Chicago. It's easier. There was another way I saw it done, schematically, using diodes. I can't remember what that one was. An old-timer showed it to me.

 

[Woodyz]

Re: California or Chicago?

Thanks George,
I believe I've got it. Don't like it but believe I may have already seen it in some shoddy commercial work ran in pipe with no neutral. The term EMF came up then.

 

[George Stolz]

Re: California or Chicago?

Originally posted by Woodyz:
Thanks George,
I believe I've got it. Don't like it but believe I may have already seen it in some shoddy commercial work ran in pipe with no neutral. The term EMF came up then.

I can get away with a lot, given my housemonkey status.

It's illegal to do with EMT, per 300.20. Hurk27 has an interesting story regarding induced currents starting near-fires, maybe he'll dive in and share it again.

 

[hurk27]

Re: California or Chicago?

Hurk27 has an interesting story regarding induced currents starting near-fires, maybe he'll dive in and share it again.

? Refresh my worn out memory?

 

[George Stolz]

Re: California or Chicago?

Hope somebody reads it cause it was a pain in the toochus to find.

 

[beanland]

Re: California or Chicago?

The EMF link to cancer has pretty well been disproved.

It takes several amps of unbalance to cause enough magnetic field to see visible effect on CRTs. Buy an LCD monitor and the problem is gone.

It takes significant unbalance to cause enough circulating current in conduit to cause heating, ususally in the 100's of amperes. (Power transformer bushings penetrate steel tanks and do not burn off the paint from circulating current in the tank wall.)

 

[milwaukeesteve]

Re: California or Chicago?

The original FARMER 3way was to take the existing 2wire drop to the barn, use those as travellers, and tie any neutral in the barn to ground at the barn(usually a cold water pipe).
Unfortunately there would be some areas surrounding the barn that the cows never walked.

Someone finally got smart and started using 3wire drops to the barns. But then the farmers wanted a 3way AND a constant hot for their electric fences. Hence, Paul's 2nd drawing.

We finally got wise and now just put a coil of wire under the high voltage powerlines that cross their property to power the electric fence. Problem solved.

 

[milwaukeesteve]

Re: California or Chicago?

Paul's first drawing is/was very common in the old Knob n Tube wiring.
This didn't really have a name to it, though. (I could come up with a few)
In know and tube, they fed a 3way switch with power and a neutral (on the traveller screws)
The other switch was ALSO fed with a hot and neutral (on the traveller screws).
Both power wires were either from the same circuit or same phase ( some older installations only had one phase to grond in the house).
Between the two switches and from each common screw a wire would go to the leads of the light socket.

When both swicthes were switched to the neutrals... light off.
Both switched to power... light still off (no neutral)
When one was switched to power, and the other to neutral... TA DAAA! Light on.

 

[physis]

Re: California or Chicago?

By Wayne:

Edited because I can't spell ether. Smile Sam