# Troubleshoot a 4-way switch circuit: instructions for a 2-year-old



## MTN REMODEL LLC (Sep 11, 2010)

I don't think you were oversimplified at all.... and will probably help alot of people.... (I did not study all the steps...leave that to someone else).

Only suggestion might be to toss in a wiring schematic to help some understand,..,. there are plenty out there somewhere in internet.

I would comment that I don't know that all four ways are as clearly marked as in/out. I could swear last one I put in was marked somewhat funny (can't remember exactly... maybe with A's and B's or something). I had to just check my continuitys in the switch.)

Best


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## Gerry_D (Jul 5, 2011)

*Kudos*

Pete, you did darn good! :thumbup:
Kudos to you.


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## Robpo (Mar 30, 2014)

Do you think you could shorten it a lot and make it so a 60 year old could read it. Maybe I will read it when I go through my third childhood:thumbup:.


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## rjniles (Feb 5, 2007)

That explanation works when the power is connected at the first 3 way and the load (light) is connected at the last 3 way. But there are other methods of wiring. The concept is the same but the wiring connections vary.

Power is connected at the light

Power and light are connected in the first (or last) 3 way.

Power is connected at the 4 way.


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## pete0403 (Dec 22, 2010)

Thanks for the comments. And true, there are other configurations. For example mine had the line cable and the light cable in the 4 way box. The power went to the first 3 way via the black wire of the 14/3 cable with the travelers and the final switched conductor came back to the 4 way box via the black conductor from the last 3 way with those travellers. 

So all kinds of different ways... But hopefully people trying this have enough of that basic knowledge to figure it out from there. 

Please feel free to post additional common (or less common) configurations... I'd be interested to hear them.


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## rjniles (Feb 5, 2007)

The problem with 3/4 way configurations (in the US) is the NEC now requires a neutral in every switch box and that further middies the water. Often 4 wire cables are required to meed this requirement.


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## Oso954 (Jun 23, 2012)

> The other might have a smaller amount of voltage on them but ignore this (this is called "induced" voltage I think and is due to not having a neutral in the switch loop) Do this by setting your multimeter to AC volts, touching the black probe to the box metal, and touching the red probe to the wires you're testing.


It is not likely to be "induced" voltage. It is more likely "phantom" voltage. Neither is impacted by a switch loop, or having a neutral in the box.

Do you think the color of the probe makes a difference when looking for AC voltage ? 
Perhaps a bigger issue might be "what do I do when my box happens to be plastic?".


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## pete0403 (Dec 22, 2010)

Oso, no i don't think colour matters. Just old habit for writing procedures for automotive DC voltage ;-) 

And I should have added to use the ground wire if the box is not metal. 

Thanks!

Also: "phantom" voltage is what i meant by induced voltage. Are the two used interchangeably? 30 feet of open wire running next to a wire with line voltage will read voltage on it due to the pulsing magnetic field running through it (one of the few high school physics lessons I remember)


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## MTN REMODEL LLC (Sep 11, 2010)

Hey Guys.... Come to think of it, (I haven't done anything new under permit since new code, is it as simple as a neutral EVERY SWITCH), regardless of whether we have a hot feed. (3 and 4 ways?)

TIA


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## Gerry_D (Jul 5, 2011)

The way I hear it the answer is a simple "yes".
( 'cept conduit, as a neutral can be inserted )
Unless localities have not adopted this one.


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## MTN REMODEL LLC (Sep 11, 2010)

Oso954 said:


> It is not likely to be "induced" voltage. It is more likely "phantom" voltage. Neither is impacted by a switch loop, or having a neutral in the box.
> 
> Do you think the color of the probe makes a difference when looking for AC voltage ?
> Perhaps a bigger issue might be "*what do I do when my box happens to be plastic?*".


Use the plastic part of the probe....:wink:


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## Gerry_D (Jul 5, 2011)

pete0403 said:


> Thanks for the comments. And true, there are other configurations. For example mine had the line cable and the light cable in the 4 way box. The power went to the first 3 way via the black wire of the 14/3 cable with the travelers and the final switched conductor came back to the 4 way box via the black conductor from the last 3 way with those travellers.
> 
> So all kinds of different ways... *But hopefully people trying this have enough of that basic knowledge to figure it out from there. *
> 
> Please feel free to post additional common (or less common) configurations... I'd be interested to hear them.


Yep, but people sometimes panic. That clouds judgement and the final picture. *I still say your's is a good solid guide.*

Just for reference, a graphic I made for another forum, ( no longer a part of because they... well, they no longer were as user friendly ), showing block diagrams of the basic methods for a three way switch. Now with adding just a single four-way, well, it gets a lot more variables. Essentially a four-way switch can be added in any *BLUE* line and MORE!

Changes to bring it up to present day codes if applicable in your area are;
*A.* Requires 4-conductor wire in right side blue line.
*B.* No changes necessary as I understand it.
*C.* Requires 4-conductor wire instead of 3-conductor
*D.* Requires 3-consuctor instead or present 2-conductor and 4-conductor instead of present 3-conductor.
*E.* Requires 4-conducor in place of both 3-conductor wires.

AS a quick count, inserting a four-way into the circuits, I see eight different ways this block diagram could be.


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## pete0403 (Dec 22, 2010)

About a year and a half since the last post. Bumping the thread up so it may help some others before it falls into the oblivion of the internets.


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## SkillsandTrade (May 13, 2017)

Maybe I can help you. This how-to video should explain everything you're looking for.


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## PolycarpElect (Jan 21, 2018)

All of the suggestions provided are excellent. This site was a lifesaver. Using it I realized that the original "electrician" had incorrectly wired the followers at the four way. I found this by doing a continuity test on the followers from the three-ways. This site (users.wfu.edu/matthews/misc/switches/confused4way.html) is also very helpful to troubleshoot 4 way switch problems. 

As noted by others, the two follower cable bundles that come into the 4 way box should be connected:
1. to the IN side (two follower wires from one of the 3 way cable bundles) and 
2. to the OUT side (the follower wires from the other 3 way's cable bundle) 
3. MAKE SURE NEUTRAL WIRES ARE CONNECTED TO NEUTRAL in the box.

The "electrician" who incorrectly wired this 4 way had taken two follower wires (black) from the 3 way follower cable bundles and wire nutted them together inside the 4 way box. He screwed the two follower wires (red) correctly -- one to the IN and the other to the OUT side of the 4 way switch. The "electrician" connected the two cable's NEUTRAL cables (white) to the remaining posts on the 4 way -- one white to the IN and the other on the OUT side of the 4 way! A definite no-no. 
:vs_whistle:

Disconnecting the blacks and whites and rewiring the black followers to the proper 4 way posts associated with their respective red (IN or OUT cable bundle), and connecting the whites to neutral fixed the issue.
:vs_cool:

We also found that the "electrician" had incorrectly wired the neutral (white) and a return wire (red) for a washroom fan timer to neutral. :vs_OMG: (OOPS!! INCORRECT). 
:glasses:

All boxes have now been checked -- and rewired as necessary. The worst offender: High power circuit to Range was connected below the range, with the wire sitting behind a drawer without a box using electrical tape and painter's masking tape! Love to see this person loose their ticket.
:vs_mad:


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## MTN REMODEL LLC (Sep 11, 2010)

Sort of associated with this.... but a joke on me in troubleshooting ......

On a flip home of mine I had a F'd up multi switch (2 4-ways) and I knew the previous non-knowledgable HO had replaced a 4-way (he told me).

So naturally I was targeting the 4-ways. I pulled them and the 4 ways can have different nomenclature on their terminals.... so I checked continuitys and installed them back as known correct.

Still did not work.

So I checked the 3-ways.... which were backstabed... and they looked ok....

So I wondered if I missed a box or a wire splice somewhere (hack HO did) and ran continuity checks on the actual wires...... up and down stairs with my long wire tester. They were OK

Well.... the stabs on these 3ways can be tricky located relative to the screw terminals. Finally discovered that the stabs were wrong when I went and redid the stabs to the terminal screws.

Lessen learned.... back stabs can be a little confusing as to terminal when you have multi terminal backstabs.:wink2:


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## NotYerUncleBob2 (Dec 29, 2017)

3 and 4 way switches always confused me until I read Rex Cauldwell's book "Wiring a House". My key take away lesson from all of this is to be consistent and methodical when wiring. Power in from the left side always, power out from the right side always, special wires labeled every time, and then when you get to something more complicated like a 4 way you don't have as much guessing or remembering to do.


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## NotYerUncleBob2 (Dec 29, 2017)

MTN REMODEL LLC said:


> Sort of associated with this.... but a joke on me in troubleshooting ......
> ...
> Lessen learned.... back stabs can be a little confusing as to terminal when you have multi terminal backstabs.:wink2:


I was waiting for you to say the bulb was burned out!


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## MTN REMODEL LLC (Sep 11, 2010)

NotYerUncleBob2 said:


> I was waiting for you to say the bulb was burned out!


Yea... That would be likely with me also..... sometimes our assumptions,,,, that you don't even realize you assumed, are what get you in trouble.

Many years ago we did a clutch on my sons Ford long bed crew cab old POS.

Involved taking out alot of electrical going thru the console etc.

Got her back together and the battery was dead (took us a week getting some parts) so we tried jumping it and NOTHING.

Naturally we assumed we had missed some harness connection somewhere... but could not find it.

Turned out our jumpers were bad.....


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## Jim_Suds (Sep 26, 2018)

Pete, you rock!
A sales sticker covered the back of the 4 way switches I purchased. Unfortunately hiding any language about "In" and "Out". Your article gave me that final piece of information and solved a puzzle that I worked on for hours. Thanks for your time to clearly explain!
Jim


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## Shadow99 (Nov 3, 2017)

PolycarpElect said:


> Love to see this person loose their ticket.
> :vs_mad:


The only ticket this guy has would be a parking ticket, and he'd be happy if you could "lose" that for him


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## Twisted99 (Oct 25, 2009)

THANK YOU SO MUCH FOR THIS.
I replaced, 2 3 way and a 4 way switch based on where the wires were located on the switch, not the color of the screws.

I'm (obviously) not an electrician, but in 30 years never screwed up that bad either.


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## pete0403 (Dec 22, 2010)

I haven't been active in awhile but glad to see this post was still helping people.


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## joed (Mar 13, 2005)

Since this post is 7 years old I think it is probably fixed by now.


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## Wiredindallas (Nov 9, 2018)

True, Joed, but post 25 (11 hours ago) was from the OP.


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