4-way switch – replace with timer switches
ahencke
| Posted in General Discussion on
Hi All,
I have a 4-way switched circuit (for a remote bath fan unit serving 3 bathrooms) and want to replace all three flip switches with timer switches. I think I understand enough about a 4-way circuit to see that my main problem is trying to replace the “4-way switch” itself. Can anyone think of a creative way to replicate the 4-way switch functionality that would allow me to put a standard (timer) switch into service instead of the purpose-designed “4-way switch”.
Andy
Replies
Not offhand, but I'm not a sparky. But, ....
You might be able to figure out how to install the timer swtiches, as controllers for a contactor that would then run the fan. Or, install some kind of timer relay before the fan, so it would stay on for a set time after any of the four way swtiches is turned off.
If these are mechanical timers, just wire all the switches "in parallel" so that any single switch will turn on the fan. Since they are timers you don't need to be able to turn off the fan from any position -- just wait for the timer to expire.
The trick is figuring out the wiring, but there should be enough wires to do this, without having to get too "creative".
It surely can be done if you..........
call my electrician. A couple yrs ago he wired two separate (2-baths) switches (timers) to a remote bath exhaust fan. I helped him pull 14-2 from each switch up to the attic where he then wired them. The feed to the fan was already in the attic. So, if you have two wire from each switch to a powered fan, it can be done.
What Dan said. I've got a
What Dan said.
I've got a similar setup for our suite bathroom where a switch and timer are wired in parallel. There is a code requirement that the fan run a certain number of hours per day for moisture control, which the timer handles, but I also wanted the switch to be able to turn the fan on during times when the timer is off.
So the result is that either device can turn the fan on, but neither one can force it off. Works great.
This design allows for as many switches as you want, but none can force the fan off. In this way it's different from a four way switch circuit.
I'll start by assuming that you have a conventional 3-way / 4-way switch install. If that's the case, you're pretty much out of you depth - indeed, most residential electricians would find it a challenge.
Conventional 3-way and 4-way switches simply cannot be replaced with even one timer - let alone a timer at each switch location.
The first thing to do is to clarify just what it is you want to accomplish. There are different timers and layouts for different purposes. For the purpose of this post, I'm going to assume that you want to simply turn a dial (the timer) at any entry to the room, and have the lights go out after you've had time to cross the room.
The first thing you need to do is rearrange your wiring. This will most likely involve some holes in the walls and new wires - though you might be able to avoid that if everything is in an accessible attic. Even then, some majore re-arrangement of the cables in the attic and the addition of multiple junction boxes will be necessary.
A typical arrangement has power feeding through a series of switches in sequence, then the last switch feeding the lights. This has to be changed.
Instead, the power will go to a box, In that box there will be a separate cable that goes to each switch location, as well as a cable to the lights. If you have three switches, that means there will be five cables entering that box.
Let's assume -there's that word again- that you want to comply with the latest code, or to allow for different types of timers. In that case, you will run to each switch location a cable that has FOUR wires in it - a red, a black, a white, and a ground. The black wire will provide power to the switch, and the red will be the return line. The white is there just in case you need a neutral (either now or later).
Your 'power in' cable will have its' black connected to all the other black wires. All the red wires will be connected to the black wire that goes to the lights. I strongly suggest you use the Wago 222-415 connectors, rather than wire nuts.With this arrangement, the lights will remain on until the last timer turns them off.
If you want any variation on this plan, you will have to make different connections. Fortunately, you have already run the cables to a common box, so you can make those connections there.
If you read the original post you'll see that this is for a shared bath vent fan -- turn on one fan from four locations. So long as mechanical timers are used (or 2-wire electronic timers), no additional wires are needed.
It is true that some "repurposing" of the wires will be needed, but with 2-wire timers you need only two wires in each box (ie, a switch leg), the wires can be shared in a daisy-chained fashion, and it should not be necessary to cut any holes or replace any wires. Certainly not necessary to "home run" each timer.
Even if 3-wire timers are used, it should at most be necessary to install a new cable from the fan to the first switch -- all of the switch boxes should already be interconnected by three-wire cables.
Vent fan or light - the load matters not. Nor does it matter if there are several switches in one room controlling a light - or switches in different baths controlling the same fan. The wiring is the same.
The switches simply can NOT be 'daisy chained' or in a row. Such would require all the switches to be on for the fan to operate. Nor can they be any manner of 3-way or 4-way switch arrangement. I've not seen a timer with a 4-way switching arrangement; if it were as simple as swapping switches, I doubt the thread would have started. Likewise, my experience with various '3-way' controls has been very disappointing, and I'd shun them. KISS.
I understand 'home run' to mean a wire that originates at the panel. At no time did I even mention the panel.
The 2011 code requires you to run the neutral - whether it is used or not. Some timers require the neutral anyway. Far earlier code require the running of a ground wire, the bonding of the box, and the bonding of the switch.
Other code issues include the various restrictionss on re-coloring the white wire for other uses, and box fill. It's certainly much easier to tell the 'feed' and 'return' wires apart when one is black and one is red.
There are timers that are located at each switch location - and there are timers where one timer is operated by different switches. The OP did not clarify what he was planning to use. There are also 'delay-off' timers that will keep the fan operating for a period aftre you turn it 'off.' Again, there are many possibilities ... I only described mechanical timers as thay are what someone else mentioned.
One important detail to watch: we have no idea how much current the fan draws. With a central fan, it's possible that the fan can draw more than the switch contacts are rated for; many timers are limited to 5 amps. If that's the case, some manner of contactor will be needed.
There's a reason electricians get licenses. It's not a topic you want to 'shoot from the lip' or BS your way through. I meant it when I told the OP he was in over his head - and that most resi electricians would also be a bit at sea on this one. Debating the meaning of the word 'is' is not going to turn on the fan. So, please, leave the student lounge philosophy in the dorm.
> The switches simply can NOT
> The switches simply can NOT be 'daisy chained' or in a row. Such would require all the switches to be on for the fan to operate.
"Daisy chaining" is done between outlets on the same circuit -- it simply means physically running the wires from one to the next. It doesn't imply placing the switches in series.
> I understand 'home run' to mean a wire that originates at the panel. At no time did I even mention the panel.
Nor did I mention the panel. "Home run" simply means running directly to some other central point, vs "daisy chaining" or using some other intermediate interconnect.
> With a central fan, it's possible that the fan can draw more than the switch contacts are rated for; many timers are limited to 5 amps. If that's the case, some manner of contactor will be needed.
Well, you'd have to be using a 12" fan to get into the 500 watt range. And even if a contactor were used, the same basic wiring scheme could be used.
> There's a reason electricians get licenses.
There's a reason that electrical engineers go through 4-5 years of college (not that this is a problem I couldn't have tackled when I was ten years old).
Nice try on the 'qualifications."
First off, having any manner of engineering degree isn't nearly enough to get you authority to sign off on prints or pull permits. TRhat, at a minimum, requires a PE license, with documented experience in directly relevant work. The head of NASA can't sign a print.
It's a dirty little secret, but electrical engineering is completely irrelevant to electrical work. It's like asking a mechanical engineer to fix your car. Every EE knows better than to pass himself off as any sort of 'electrical' authority.
Look at the curriculum of any engineering program, and you'll find no reference to raceways, wiring methods or codes. Engineers are taught to crunch numbers - not to actually make anything.
Now, if someone out there who is actually qualified - in the legal sense of the word, as in having a government issued license - wishes to find fault with my description, I'm all ears. Bluster is otherwise busted. There's no gold stars awarded for sounding like you're the smartest guy in the room.
Myself? I leave the thinking to the horses; they have bigger heads. :D
The OP started off asking about 3-way and 4-way switches. While commonly used for household lighting, they're a glaring exception to the rule that switches be placed in parallel. Being in series - one in line with the others- precludes them from working with timers at the switch locations. So there's no way to avoid having to rearrange some wire runs.
BTW: Wats drawn by a fan has little relevance in sizing things. One simply must see the nameplate and apply the appropriate rules. Since the OP has not described his central fan, we have no idea whether his timer contacts can handle the motor load.For all we know, the fan already has a contactor and termination points in it already.
That's why design specifics need to be left to the pros.
And since when does having a government-issued license control how electrons flow?
I know perfectly well how 3-way and 4-way switches work, and I've known that since grade school. (The honest truth.) But if you'd just set aside your obstinance for a moment you'd realize that these are timer switches, and wiring them in parallel will yield precisely the type of action the OP desires -- no need to reproduce 3-way/4-way action.
What the OP wanted to do is replace all four switches with timer switches, and this is perfectly feasible if the timers are 2-wire devices (as virtually all mechanical bathroom timers are). All the necessary wires (pre-2011 code) are there, and in this situation the wiring would be "grandfathered" just as if you were replacing a switch in a switch leg. (In fact, if power is fed from the far end then the whole setup would meet 2011 code without any new wires.)
You're wrong. Set it up on a workbench ... you'll see.
3-way's are in series. Timers are in parallel.
> 3-way's are in series.
> 3-way's are in series. Timers are in parallel.
Correct.
> You're wrong.
Incorrect.
In electronics jargon the switch leg would be converted into a "bus" -- a "wired OR" -- such that any timer on the bus could activate the fan. If multiple timers activate the fan then so what? You wouldn't want the second timer to turn the fan OFF, would you?
Like I said, the wires need to be "repurposed" to a degree, but the necessary (and legal, prior to 2011 code) wires are there, assuming the wiring was legal to begin with.
There are three basic cases:
Power feeds to the fan, with the switches in a "switch leg".
Power feeds to one end of the switch chain, with the fan on the other end.
Assorted cases of power and/or fan connecting in the middle somehow (though generally these devolve to either 1 or 2 after you sort out the wire flow).
In the first case there'd be a 2-wire cable from fan to the first switch, then 3-wire cable from there on to the other switches. The 2-wire cable is a conventional "switch leg". Simplest approach is to ignore the "odd" wire in the 3-wire cable and wire-nut black to black, white to white through all of the boxes, with pigtails on each wire nut. Then attach the (two-terminal) timers to the pigtails. (Purists may prefer to use the odd-colored wire in place of the white wire, but there are arguments both ways.)
In the second case you have a 2-wire cable coming into the box at the far end, supplying power, and a 2-wire cable coming out of the box closest to the fan, feeding power to the fan. 3-wire cables in-between. Again, wire black to black, white to white, with pigtails, EXCEPT at the box closest to the fan wire the odd-colored wire to the black wire feeding the fan. Then install your timers between black and odd color, using the neutral if you have 3-terminal units.
(I'm not going to go into the third case, since it requires individual analysis based on the "situation on the ground".)
With either setup I'd be strongly tempted to install a service switch at the fan, "in series" with the power feeding in.
What Dan said ... you wire the crank timers in parallel and I'm thinking he's right ... it should be doable. This means turning each switch into a simple on/off configuration which should be doable with 3 leg wiring. I wired three switches in parallel in my new house for the exact same purpose as your situation. I should have done 3 crank timers as it tends to be easy to leave them on a little too much especially w/ the super quiet Panasonic fan I bought.
Let's put it down in simple terms.
In a 3-way/ 4-way switching arrangement, things are laid out like this:
Power -> 3 way switch -> 4 way -> 3 way -> the fan.
With timers, it goes like this:
Power -> split the power to go directs to each timer -> bring the second wire from each timer to the fan.
I don't care how you look at it, there is never a place where the wires between the 3-way switches go to the fan. Therefore, you cannot reconect the wires in any combination that will have them in parallel.
In a room where all the junctions are made in the box above the light, one might be able to rearrange the connections. In a house where different baths are served by a remote fan, I doubt you'll find everything going to the same single box at any point- which brings us right back to Amish's original post - adding boxes and running more wire.
There's no getting around it- the wire from the 4-way has to go to the fan - NOT to either of the 3-ways. The remaining wire to the remaining 3-way is not used. Likewise, the wire feeding power to the first 3-way needs instead to tie into every other switch directly.
With layout #1 you'd have:
power
| (2 wires)
V
Fan -> (2 wires) -> 3-way -> (3 wires) -> 4-way -> (3 wires) -> 3-way
With layout #2 you'd have:
power -> (2 wires) -> 3-way -> (3 wires) -> 4-way -> (3 wires) -> 3-way -> (2 wires) -> fan
In either case there are enough wires to use 2-terminal mechanical timers. In the second case you could use 3-terminal (hot/switched/neutral) timers if you wanted.
I'm pretty sure there's be enough wires even in various center-feed/center-load scenarios, but they're too complicated to enumerate.
Draw it out, I don't think there is any possible way to use only the existing wires and single pole timers.
Can someone post a diagram? In my mind it sounds pretty simple to do, but then again, it may just be my simple mind.
OK, a diagram.
Yeah, that's exactly what I did (#1). Simple.
Any timer can turn it on, none can force it off.
Sorry I didn't get my diagram proving it can be done posted before yours supposedly proving it can't be done.
Any more questions?
(I can't believe a simple switch circuit problem kept people so bollixed up for so long.)
I guess we should all draw more....
Actually, I just worked it out in my head. I'm not really a "visual" person.
You be "gifted". I figure
You be "gifted".
I figure you're plenty visual, it's just that it all happens all in your head.
On the other hand, Mark's drawings were way prettier compared with your hen scratching.. You need to work on that angle. ;-)
What are the seven deadly sins? Well, let's atone for some pride here .....
I will work, as drawn. It just involved some connections that most of us are used to avoiding. Call it 'thinking inside the box.'
OK, college boy, you have earned the privelege of sleeping late tomorrow. Say, until 4:30 :D
Well, I see my work here is done.
Dan, I award you the title of Switchmaster.