Chicago Circuit

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Mike01

Mike01

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MidWest
I know these types of circuits were used durring the depresion, and have been illegal for a long time now I believe 60+ years but having some conservations with a couple of old time retired electricians / engineers I herd the topic of a "Chicago Circuit" it was a way to wire a three-way circuit using only two conductors. Does this sound familiar to anyone, just from a curisoty stand point I have been trying to work this out (on paper, a diagram) but I am clueless anyone have any suggestions or experience with this type of circuit or even a wiring diagram I would like to see how they actually operated. thanks in advance.:)
 
Very simple. At the bottom of the stair, bring a 2-wire from an outlet to a 3-way switch. Connect hot from the outlet to the 3-way common. Run a 2-wire from the 3-way to the second 3-way. Travellers only. From the 2nd 3-way to the light, connect the common to the light, then use a 2-wire from the light to find a neutral somewhere.

In the end, I don't think any of the installations I've seen saved one bit of copper. What it did save was the electrician from having to purchase any 3-wire cable. Back in the day, 3-wire cable was not common, as a typical home had maybe 4 circuits, and no 220v meant no 3-wire multiwire circuits.
 
At least the above approach doesn't switch neutral.

An approach used in the era of K+T wiring was as follows:

Run Hot and Neutral to each switch, meaning 2 wires from the receptacle circuit to the switch. Connect H and N to the _traveller_ terminals at each switch. Run a _single_ conductor from the common terminal of each switch to the light.

With both switches connecting N to common, the light is off.

With one switch connecting H to common, and the other switch connecting N to common, the light is on.

With both switches connecting H to common, the light is _off_, but both terminals of the light are energized to 120V.

Clever and evil all at the same time :)

-Jon
 
I believe that these were also referred to as "lazy Susan 3-ways", at least in this area. As they switch the neutral, they are no longer a valid wiring method. You have to admit that it is pretty creative!
 
Let me Blame the Chicago circuit

Let me Blame the Chicago circuit

Well I don't know if it was the the Lazy Susan or the Chicago Circuit.

I had a simple switch at the bottom of the Stair, no Problem my
Church friend says, I can wire you a three way switch with exiting service,
well that got me to think'n, well no I said, thank you just the same.

I found some vocational classes and took all they offered, after one
class year as a Teacher, I had my summer free so I hooked up with a
large EC service. Theres something about Big Pipe and Big Wire, I was hooked.

I just couldn't stand the fact that one, he offered to BS a rig on my
house, and two I didn't understand how he could get it to go on a 3 way
situation. Frankly I can only think that he was going to use the third wire.
I can't recall now, because I removed all the wire that that I could reach
It was 2 circuit Tar weave. circa' 40's.
 
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