# Three way switching standard, coast, carter



## simmo (Dec 12, 2007)

Not familar with your switches in America, but are you talking about a rotary type switch On-Off-On 
or a Double throw/Double pole type switch (DTDP) ?

We only switch the active in Australia and run the neutral straight back from the downstream side of the load. For three way switching we would use three switch mechanisms with the middle mech wired in loop with the other two (point to point) wiring. A little hard to explain, but it works for me. lol


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## RePhase277 (Feb 5, 2008)

We just had a discussion about this on Contractor Talk. The "coast" or "California" 3-way is a legal setup, even if confusing. It actually uses the same amount of conductors as a regular setup, it just allows you to take a constant hot out to the remote location.

The "Carter" 3-way was legal until 1923, when the Code specified the screw shell of the lamp socket to be the grounded conductor. I have seen this setup a few times in rural areas I've worked in. It will drive you slap batty trying to figure it out if you aren't expecting it.

InPhase277


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## simmo (Dec 12, 2007)

Is that a socket outlet on the far right side of those diagrams?

Here - that would not meet our codes, no light and power is mixed. Must be seperate light and power circuits.


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## 5volts (Jan 11, 2008)

Actually the coast threeways purpose was because way back only 3 #12 TW wires were a loud in a 1/2 inch conduit. The city of LA a loud 4 #12 TW wires as long as one of the wires was being used as a switch leg. This aloud you to still use a 1/2 conduit. The coast also saves one wire as you only need 4 wires including hot and neutral. The Edison 3 wire three-way requires 5 wires including hot neutral. The Coast is legal but serves no real purpose anymore.


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## RePhase277 (Feb 5, 2008)

simmo said:


> Is that a socket outlet on the far right side of those diagrams?
> 
> Here - that would not meet our codes, no light and power is mixed. Must be seperate light and power circuits.


Right, these are non-standard circuits. Here, it is good practice to keep lighting and power separate, but it is not required by code. Good electricians do it anyway.

Notice the "Carter" setup. It is not a code compliant system because it switches the neutral and at times the screw shell of the lamp socket can be energized. This has been outlawed by the National Electrical Code since 1923.

InPhase277


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## jrclen (Oct 23, 2007)

I run into the Carter system from time to time on farms. Mostly wires run between the house and the out buildings. Put in years ago.


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## frenchelectrican (Mar 15, 2007)

the other thing with " Carter system " when you upgrading the service you have to becarefull with them some of them dont use the same circuit for the carter system.

and it did happend to me once long time ago when i was upgrading and heard a light bulb expoled i say " aww Merde " i knew it away took me a while to find the right leg and got that switch and related circuit fix up and brought up to the code anyway.

Merci, Marc


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## jrclen (Oct 23, 2007)

frenchelectrican said:


> the other thing with " Carter system " when you upgrading the service you have to becarefull with them some of them dont use the same circuit for the carter system.
> 
> and it did happend to me once long time ago when i was upgrading and heard a light bulb expoled i say " aww Merde " i knew it away took me a while to find the right leg and got that switch and related circuit fix up and brought up to the code anyway.
> 
> Merci, Marc


Good point Marc. Those circuits can be hard to figure out until it dawns on us what we are looking at. In the farm buildings I find more wires have been added later but the Carter is still there in the mess. That makes it difficult to spot sometimes. And can surprise us.


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## frenchelectrican (Mar 15, 2007)

there one trick related to this crazy carter system.

instead try to edit my last post but let me add it here with old fuse box where they have double or tripleed even once quadded at fuse connection what i do i take a colour tape so i mark it so i know which leg it was on by time i install new panel box.
it it will be on correct leg so i dont blow it again like what it done to me before.

Merci, Marc


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## JohnJ0906 (Jan 22, 2007)

I like this diagram, as it moves.


Sorry, I can't give proper credit to the person who originally posted this.... as I forgot who it was. :001_huh:


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## jrclen (Oct 23, 2007)

frenchelectrican said:


> there one trick related to this crazy carter system.
> 
> instead try to edit my last post but let me add it here with old fuse box where they have double or tripleed even once quadded at fuse connection what i do i take a colour tape so i mark it so i know which leg it was on by time i install new panel box.
> it it will be on correct leg so i dont blow it again like what it done to me before.
> ...


Good idea Marc.


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## waco (Dec 10, 2007)

Best I can recall, the only odd configuration of three-ways I have found are the "derived" neutral at one end. I long ago began using a "standard" method so anybody who comes across my circuits won't have to figure out what I did.


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## jrclen (Oct 23, 2007)

waco said:


> Best I can recall, the only odd configuration of three-ways I have found are the "derived" neutral at one end. I long ago began using a "standard" method so anybody who comes across my circuits won't have to figure out what I did.


What is your standard method? Just so I'll know it if I see it. :thumbup:


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## waco (Dec 10, 2007)

jrclen said:


> What is your standard method? Just so I'll know it if I see it. :thumbup:


Always three wire traveler -- never run through the device. Always red and black travelers and either taped white if used for a feedback or plain white if used for neutral.

However, I never did standardize on which end to feed and which end to loop, but I generally feed and loop opposite ends if I can.


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## 480sparky (Sep 20, 2007)

Here's my movies:


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## waco (Dec 10, 2007)

The problem I have with this setup is that there is no neutral (that I can see) to the fixture. Also, all my detached garages have to have a sub-service anyway, so I use 10-3 with ground to the sub-panel and just wire normal lights from there.

My three-ways for exterior lighting at a detached garage use 14-3 on a normal three-way from the house.


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## JohnJ0906 (Jan 22, 2007)

waco said:


> The problem I have with this setup is that there is no neutral (that I can see) to the fixture.


Some times it has a neutral... any time the lamp is on. Sometimes it has 2 neutrals, sometimes 2 hots - anytime the lamp is off.

Definitely a screwy set-up, thats for sure.

I would hope that no one would wire a 3 way like this new. But it is important to understand, just in case you run into one on a service call, or some old work job.


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## Pierre Belarge (Feb 3, 2007)

JohnJ0906 said:


> Some times it has a neutral... any time the lamp is on. Sometimes it has 2 neutrals, sometimes 2 hots - anytime the lamp is off.
> 
> Definitely a screwy set-up, thats for sure.
> 
> I would hope that no one would wire a 3 way like this new. But it is important to understand, just in case you run into one on a service call, or some old work job.


 
The 3-way to the garage that 480 posted is not a permitted installation and can be dangerous.

As I highlighted, it is only important to understand for troubleshooting purposes.


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## jrclen (Oct 23, 2007)

Pierre Belarge said:


> The 3-way to the garage that 480 posted is not a permitted installation and can be dangerous.
> 
> As I highlighted, it is only important to understand for troubleshooting purposes.


Absolutely Pierre. We all agree these are not permitted wiring methods and haven't been since any of us were alive. And they are dangerous. Unfortunately they were still wired up in my area this way in the 50's and maybe even the 60's. On farms mostly.


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## johnny x (Mar 9, 2010)

I ran into something similar, but different from what I've seen here. It baffled me for quite a while. I can't figure out how to attached a sketch here, so I'll try to describe it. 

Imagine a light between two 3 way switches. The light is fed off the common of each switch with a black wire. The white wire is not used. The other switch terminals are connected to hot and neutral from two different circuits. 

In this configuration, the light is turned "off" by putting 110V on each side of the load.

Anyone seen anything like this? Does it have a name?


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## 480sparky (Sep 20, 2007)

johnny x said:


> ....Anyone seen anything like this? Does it have a name?


 
California, Farmer, Illinois, Power-Beyond, Carter, 3-wire/3-way, Homeowner, Jacked-in, just to name a few.


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## johnny x (Mar 9, 2010)

Thanks... didn't recognize right away from your diagram. 

I guess the only difference in what I ran into was that each switch was fed from a different circuit breaker. 

After hitting one of the breakers, I was surprised (and a little confused) to find the circuit was still hot.


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## sidewinder (Jun 28, 2009)

johnny x said:


> Thanks... didn't recognize right away from your diagram.
> 
> I guess the only difference in what I ran into was that each switch was fed from a different circuit breaker.
> 
> After hitting one of the breakers, I was surprised (and a little confused) to find the circuit was still hot.


 
Generally, in the perfect scenario, on a carter, you should try and use the same circuit. If not the same circuit, at least on the same phase so as you don't have 240 V going to the light when the light is off. Same thing on a coastal. Try and use the same circuit.


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## JohnR (Apr 12, 2010)

I been schooled ! 

And i thought I was pretty good on three ways!:laughing:
I never saw or even thought of either of these methods. wow thanks guys.:thumbsup:


I know with the carter system I would have been totally stumped. and besides that of course would have wired it "normal" but would have had been confused on how it worked in the first place.


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## Bkessler (Feb 14, 2007)

I wire my three ways which ever way is easiest at the time I am roughing, power can be at the light, the same switch as the switch leg or the far side of the switch leg, same with four ways, If I have a box that can handle it I'll put the power and the switch leg at the four way. Why does anyone care if some future person is going to know whats going on. If you can't figure out how a three way switch works you probably still a helper.


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## Widestance_Politics (Jun 2, 2010)

Bkessler said:


> I wire my three ways which ever way is easiest at the time I am roughing, power can be at the light, the same switch as the switch leg or the far side of the switch leg, same with four ways, If I have a box that can handle it I'll put the power and the switch leg at the four way. Why does anyone care if some future person is going to know whats going on. If you can't figure out how a three way switch works you probably still a helper.


Agreed...I learned many different ways to wire three and four ways after trouble shooting them doing service work.....now on the job I look at what is going to take the least amount of time or material and rough it in accordingly...I have had a handfull of arguments with 4-5th years and the ol' guys who just see it one way and rather than listen or try to understand it I usually get the eye roll....until the light comes on and I revel in silent victory:thumbup:


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## macmikeman (Jan 23, 2007)

We are all going to learn a new way come 2011 adoption. That is to bring a neutral into each switch box whether or not you even need one. One boss I used to have would only let us power to the lights and break the travellers there. All fine and dandy until you have to trouble shoot something and then you have to grab a ladder and remove a light fixture to get to the connections. Leads to macmikeman axiom #68: A troubleshooting job for a three way or four way switching problem on a "fed the light and the threeways in the fixture job" will only occur after hours when it is dark and you will be having to remove the light source.... . axiom #68 is moot for those who have to suit up in ppe to troubleshoot resi wiring anyway cause they always work with the breakers off.


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## 480sparky (Sep 20, 2007)

macmikeman said:


> We are all going to learn a new way come 2011 adoption. That is to bring a neutral into each switch box whether or not you even need one............


No biggie. Just run 14/4 instead of 14/3.


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## frenchelectrican (Mar 15, 2007)

There is 2.5mm² and 4.0mm² quads { 14-4 and 12-4 } on market but once the 2011 code kick in you will see those item become common but just wait one of the day someone will come up with cinq cable now that getting instering.

Merci.
Marc


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## 480sparky (Sep 20, 2007)

frenchelectrican said:


> ............ but just wait one of the day someone will come up with cinq cable now that getting instering.
> 
> Merci.
> Marc



Cinq cable?


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## Rudeboy (Oct 6, 2009)

480sparky said:


> Cinq cable?


14-5, 12-5, 10-5 etc.


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## DERITM (Apr 8, 2009)

Also, never ever put a mercury switch in a "hot" 3 way. Boom!


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## Rudeboy (Oct 6, 2009)

If you run power to one switch and switch leg to second switch and 14-3 from switch to switch you will have a neutral in both boxes constantly. I guess running 14-4 would be useful for a dead-end three way?

I've used 12-4 mc many times but never 14-4 nm.


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## MDShunk (Jan 7, 2007)

DERITM said:


> Also, never ever put a mercury switch in a "hot" 3 way. Boom!


Unless it's a rewire job, where you're reusing the old devices (bad practice), this will never be an issue.


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## Kyle1500 (Feb 17, 2021)

Speaking of the carter 3 way, yes, i never personally dealt with it before i purchased my home a few years back. This forum helped me a lot. Btw it was not a legal install at the time of the built. My home was built in 1958, with a small tool shed that was build on the property in 1976. With a 12/3w/g UF cable run between the light switch in the laundry room, and the toolshed, with a couple receptacles that remain hot at all times, and an 8 footer fluorescent on the three way switch. wired carter style. I discovered the ballast wired were wired to the red conductors in the UF cable when i was performing an LED upgrade. A whackey setup. The first three way in the laundry room has the black and white conductors connected to the two traveler's via a pigtail to the 12/3 ground UF. Red conductor connects to common. In the toolshed, there is an 8 foot fluorescent, hot and neutral wires on the fixtures ballast are connected to two red conductors, while the black and white are each connected with a wirenut, next, i have 12/3 with Ground ROMEX run from that point to the three way in the toolshed, the red connects to the common, the black and white pigtails to the traveler's, then continues on with 12/2 with Ground ROMEX to feed 6 receptacles inside the shed. Intresting enough, there are actually gfci protected. Seems way too modern of an install to be using a long illegal and dangerous method, is it possible that 12/4 UF is not manufactured. As i mentioned, the toolshed was built in 1976.


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## hornetd (Oct 30, 2014)

simmo said:


> Not familar with your switches in America, but are you talking about a rotary type switch On-Off-On
> or a Double throw/Double pole type switch (DTDP) ?
> 
> We only switch the active in Australia and run the neutral straight back from the downstream side of the load. For three way switching we would use three switch mechanisms with the middle mech wired in loop with the other two (point to point) wiring. A little hard to explain, but it works for me. lol


Don't you call the single pole double throw switches 2 point switches and the double pole double throw switches multi point switches? Or am I confusing Australia with the UK? 

-- 
Tom Horne


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## mofos be cray (Nov 14, 2016)

You got your paleontology tools out for this thread eh boys? 
Cause it's a dinosaur.
I'll show myself out.


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## Wiredindallas (Aug 9, 2018)

I was once working on an old house once owned by an electrician which had a "Carter or California" 3 way. I figured out what I had, so I went to the College Library and researched it. I finally found it in the 1925 NEC book. There they said to not do it this way.


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