# Carter System?



## hbgorr (Mar 19, 2009)

A Carter system is an old style method used with knob and tube wiring. The hot and neutral are the travellers and the load is the common. Basically you are switching the polarity of the socket itself. It is not allowed by the NEC anymore, but I still see them now and then.


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## electricista (Jan 11, 2009)

Is this it?


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## 480sparky (Sep 20, 2007)

Carter 3-ways allow for 3-way switch operation and can keep power on all the time at the far end for a receptacle. Typically used between a house and detached garage with 3 wires.

AKA California, Illinois, Chicago, Farmer and Power-Beyond 3-ways.


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## hbgorr (Mar 19, 2009)

this is a good picture of a carter system, but not a california or carter system. these systems are still legal by the NEC but pretty unpracticalbe now a days.


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## 480sparky (Sep 20, 2007)

hbgorr said:


> this is a good *picture of a carter system*, *but not* a california or *carter system*. these systems are still legal by the NEC but pretty unpracticalbe now a days.


Huh???


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## frenchelectrican (Mar 15, 2007)

hbgorr said:


> this is a good picture of a carter system, but not a california or carter system. these systems are still legal by the NEC but pretty unpracticalbe now a days.


 Quoi?? :blink:

Ils n'étaient plus légaux depuis années 1930.


( They were no longer legal since 1930's )

Merci,Marc


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## waco (Dec 10, 2007)

I can see the problem with the system posted by Sparky, but I don't see a problem with the one pictured by Elecricita. What am I missing?


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## electricista (Jan 11, 2009)

waco said:


> I can see the problem with the system posted by Sparky, but I don't see a problem with the one pictured by Elecricita. What am I missing?


For one the neutrals are in parallel in mine. BTW, I think mine is called a travelling buss 3- way. Violation of 310.4. Also if there is ferrous metal raceway involved then it is a violation of 300.20


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## perry1 (Mar 18, 2009)

frenchelectrician; as far as i know the california 3 way 4 way is still legal, it would allow you to have a light on the house & 1 on the out building to turn both on & off with the 3 way switches using 4 conductors & supplying power to out building, perry


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## electricista (Jan 11, 2009)

perry1 said:


> frenchelectrician; as far as i know the california 3 way 4 way is still legal, it would allow you to have a light on the house & 1 on the out building to turn both on & off with the 3 way switches using 4 conductors & supplying power to out building, perry


I don't believe a california 3 way be legal. If the picture that 480 sparky posted is a calif. 3 way then there is no way it is legal. Look at the gif image and see the neutral is being switch.


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## RePhase277 (Feb 5, 2008)

electricista said:


> I don't believe a california 3 way be legal. If the picture that 480 sparky posted is a calif. 3 way then there is no way it is legal. Look at the gif image and see the neutral is being switch.


The "Carter" 3-way is the one that 480 posted. The "California" and "Coast" 3-way are the same. They are still legal, but really kinda pointless.


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## electricista (Jan 11, 2009)

InPhase277 said:


> The "Carter" 3-way is the one that 480 posted. The "California" and "Coast" 3-way are the same. They are still legal, but really kinda pointless.


Okay so where is the diagram of a calif. 3 way. According to 480 they are the same as the Carter 3 way.



480sparky said:


> AKA California, Illinois, Chicago, Farmer and Power-Beyond 3-ways.


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## RePhase277 (Feb 5, 2008)

electricista said:


> Okay so where is the diagram of a calif. 3 way. According to 480 they are the same as the Carter 3 way.


The top diagram is a california. The bottom is the carter. Some may use the terms interchangeably, but most call them as I have diagrammed them. The California was devised at a time when the code there only allowed for 3 conductors in 1/2" EMT, with an exception for 3-way switches. This system allowed for power to be taken to a remote building for a receptacle, and switching for a remote light.


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## electricista (Jan 11, 2009)

InPhase277 said:


> The top diagram is a california. The bottom is the carter. Some may use the terms interchangeably, but most call them as I have diagrammed them. The California was devised at a time when the code there only allowed for 3 conductors in 1/2" EMT, with an exception for 3-way switches. This system allowed for power to be taken to a remote building for a receptacle, and switching for a remote light.


Thanks for the help. Apparently I did not see the images you posted of the two switching systems before I posted. I saw your post but not sure how I missed the image. :thumbup:


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## 5volts (Jan 11, 2008)

InPhase277 said:


> The top diagram is a california. The bottom is the carter. Some may use the terms interchangeably, but most call them as I have diagrammed them. The California was devised at a time when the code there only allowed for 3 conductors in 1/2" EMT, with an exception for 3-way switches. This system allowed for power to be taken to a remote building for a receptacle, and switching for a remote light.


To add here is the story i have been taught about the coast threeway.

Back in the 1930's 40's, 50's and early 60's 
Romex, BX or armored cable was not allowed
in the City of Los Angeles. House wiring was done in 
black iron pipe. The wiring at that time was RHH or later TW wire.
At that time the NEC allowed 3 #12 wires in a 1/2" conduit. 
(most wiring was #12). If you wanted to carry the 
hot and neutral with your circuit it would require 5 wires 
and a 3/4" conduit when using the standard or Edison 3 way.

The City of Los Angeles created its own code book. It added addendum
pages to the NEC and precluded sections at will. The L.A. code allowed a
4th #12 wire in a 1/2" conduit if one of the wires was a so called
switch leg or traveler. Therefore, with the Coast 3 way you not only
saved 1 wire but also a conduit size if you wanted to carry the hot and
neutral with the 3 way. The Coast 3 way was developed here to save 1
wire and 1 conduit size.

Finally the Federal Gov't, namely HUD threatened to withdraw building
funds from the city of L.A. if they didn't accept Romex and BX as
legitimate wiring methods.

NM cable was introduced in Oklahoma as a means to reduce wiring costs.
Hence the name Okie Rope. Since the new wiring methods were adopted 
and the advent of THHN wire, alas, the purpose for the coast 3 way no 
longer exists. 












It is called a "coast" or "California" 3-way. Often, this same basic arrangement is wired in such a way as to accommodate two loads, one at the beginning and one at the end of the run (figure 6).










I agree with InPhase277 The carter wiring system is the one that 480sparky posted. As far as the "Coast" I have heard it being called the "California threeway", but that is usually from people that are not from Los Angeles. "The Coast" and this story behind it is what I 've been taught and hear from Electricians who actually seen the city of LA's codebook .


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## bobelectric (Feb 24, 2007)

No longer legal to install, but we still have to service it.


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## 480sparky (Sep 20, 2007)

bobelectric said:


> No longer legal to install, but we still have to service it.


You can service them all you want. I'll replace them instead.


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## perry1 (Mar 18, 2009)

p-logix; very good! easy to under stand, if you had a a building far from house you could have a light at the house and 1 at out building very easy. using a convenial 3 way's would require a 5 th wire to feed back to the house light. now add the 4 way switch to the coast/calif circuit. perry


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## hbgorr (Mar 19, 2009)

sorry. mistyped that one.


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## Dayvieboy (Jan 16, 2017)

*Carter System 3-Way Wiring*



480sparky said:


> You can service them all you want. I'll replace them instead.


The knob & tube wiring for the chandelier above the stairway has 1 wire running to the top of the stairs and one wire running to the bottom of the stairs.

Replacement will require getting behind wainscoting, fishing plaster & lath for days. Then you'll never match the texture of the plaster even if done by a pro.

One of the 3-ways is still a push button
Has worked fine since 1890's

Customer obviously has no interest in taking on this project  











Problems:
1. Switching neutral not since 1923 allowed
2. 1/2 of the time the shell of the lamp socket is hot
3. Cannot be dimmed


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## backstay (Feb 3, 2011)

8 year old thread.


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## Lone Crapshooter (Nov 8, 2008)

I do understand why a Carter 3 way is illegal that is a no brainer. The Coast 3 way in a conduit with all of the circuit conductors in 1 conduit I just see the problem with it.

As a matter of fact I use the Coast between the house and the garage because I have different sections of the garage on different switches but all on 1 lighting circuit and a 3 way switch that I can turn some lights on and off from the house.

I just can't see the problem with a conduit install.

LC


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