7 way lights

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  #1  
Old 04-15-06, 08:41 AM
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7 way lights

I have a hallway lighting circuit that is 600W, will be switched from 7 locations ( yea I know thats alot of 4 ways) and has a combined run length from the panel thru all the switches and to all the lights of 400' !! I was gonna use #12 but I think I should use 10-3 for all my swith legs to avoid a large voltage drop...... Could really use some help on this one........
 
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  #2  
Old 04-15-06, 10:02 AM
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I think your at about 6% drop with 12awg. I'd live with that, especially with a lighting load.
The real issue, is if you wire all this up and ur wife now wants dimmers.
 
  #3  
Old 04-15-06, 10:12 AM
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I have to plan for the worst......She may want dimmers.... How will that affect my drop??
 
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Old 04-15-06, 10:18 AM
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no effect. Of course, the dimmers reduce your load from 5 amps to something less than that, further reducing your voltage drop in the wires. Note that many, if not most dimmers are rated at 5 amps max.
 
  #5  
Old 04-15-06, 10:26 AM
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I know it is considered "sloppy" by some to mix wire sizes, I may still use 10-3 for all my switches since I have a roll of it that I bought before it required a 2nd mortgage to do so.......I, of course, will still use a 20A breaker. thanks for all the help.....
 
  #6  
Old 04-15-06, 12:10 PM
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Originally Posted by Hooter
a combined run length from the panel thru all the switches and to all the lights of 400' !!
If you subtract the panel to the lights, how far?

You have a case here that asks for a control circuit rather than running so much heavy copper.

How much is fluorescent lights?
 
  #7  
Old 04-15-06, 12:35 PM
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I have a long T shaped hall. From panel to switches = 66' Then to tie all the switches, it is 170'. Then, I will put the power to the lights kinda in the middle so I will go one way 110' and the other 98'. I am bringing power in at closest switch (a 3-way) and will run my switch leg from the same box. So I have figured the shortest run to link all the 7 switches and it is 170'.

I am hard-wiring a Lutron control for all my lights but wont put it in for a while and still want to maintain manual control for now. No fluorescent in this circuit. One more bit of info that may or may not matter.......The power leg from the box will supply another lite circuit of 800W that is on a 3 way/4 way with 4 switches. These runs are much shorter.

I think I will have to at least run a 10-2 from the panel, but I dont mind pullin the 10-3 since I have it and I dont back stab anything. I dont mind bendin the heavier wire, just gotta watch my box fill calcs......
 
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Old 04-15-06, 04:54 PM
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> I have a long T shaped hall.
How long are the arms and leg?

> From panel to switches = 66'.
I assume you mean to the first switch.

> Then to tie all the switches, it is 170'.

I'd have to see your layout.
Are you having to drop below the floor or go above the ceiling to pop in to each switch?

Your shortest route should be to start at one of the three endpoints of the tee (ideally, not the shorter arm) with a 3-way switch.
Then you run the shortest arm, backtrack, and run the remaining arm/leg and end with a 3-way.

From your starting switch, you proceed to the nearest light wherever that is.

> Then, I will put the power to the lights kinda in the middle

Should be and end point nearest where the first 3-way switch is.

> so I will go one way 110' and the other 98'.
Doesn't sound exactly like a tee.


> I am bringing power in at closest switch (a 3-way) and will run
> my switch leg from the same box.

Switch leg? A switch leg occurs when you bring power first to the light.


> So I have figured the shortest run to link all the 7 switches and it is 170'.

Could be.


> No fluorescent in this circuit.
Cutting current reduces voltage drop.

> The power leg from the box will supply another lite circuit of 800W that
> is on a 3 way/4 way with 4 switches.
> These runs are much shorter.


> I think I will have to at least run a 10-2 from the panel,
- or use 10/3 and make it a multiwire so that when both set of light are on you'll have less voltage drop rather than more.


> I don't mind bending the heavier wire
into about 63 loops for the switches!


> just gotta watch my box fill calcs.
So you are looking at 17.5 cu in?
Even then, stuffing #10 on four-way switches into any switch box is not easy.
 
  #9  
Old 04-15-06, 05:20 PM
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Note that you can avoid the backtrack with three-wire cable on the short arm by using four-wire cable on the short arm from switch to switch. But then you need 25 cu in boxes (assuming 10/4). It does shorten the path that the electric must follow because the short arm is traversed only twice instead of four times.
 

Last edited by bolide; 04-16-06 at 02:44 PM.
  #10  
Old 04-15-06, 05:30 PM
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My layout is a little complicated but I can try to get it into an e-mail if you want to see it......

The shape is like an F with the top of the F reveresed.....I said T since thepull is very close to that shape......

66' to first switch

House is slab built so all pulls are overhead but my measurements include the drop

I do have the switches figuered to the shortest pull.....Power comes in to end 3-way ( call it switch #1), "travels" thru all the other switches and back thru box that switch #1 is in and then to closest lite. Makes run too long if I go to end of lite run.....That lite is in approx center so I will have power going 2 directions from this lite. It will have switched power in, power to 6 other lites in one direction, power to it and 4 other lites the other direction. So, the box at that lite will have three 12-2 w/ground and the lite pigtails.

I know it sounds confusing......Hope this helps......
 
  #11  
Old 04-15-06, 07:37 PM
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> The shape is like an F with the top of the F reversed..... I said T

That's fine. Topogically it can be folded into a T.

> I do have the switches figured to the shortest pull.....
> Power comes in to end 3-way ( call it switch #1)

You say "end", but how is it that the light nearest this switch is in the middle?
That's what I don't follow.
An end switch has to be closer to the light at that end than to a light in the "center".

> ... switch #1 is in and then to closest lite.

This much sounds correct.


> Makes run too long if I go to end of lite run.....

No, the switch is already at the end, so the light has to be at that same end.


> That lite is in approx center
How can this be unless there are no switches in one half the hallway?


> I know it sounds confusing......
at least to me it does.

Generally speaking, the two switches that are mutually furthest from each other should be the three-way switches (some exceptions may apply) in order to use the least material.
I can't tell whether you have selected these two.
Then you bring power to the one of these that is nearer to the panel.
 
  #12  
Old 04-15-06, 08:39 PM
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Let me try to explain...The switch (switch #1) is in the croutch of the center arm of the F. The panel is closest to that switch. Assume that the top of the F is North. The lower leg of the F going from crotch to South is 70'. From the croutch North to the top of the F is 30'. The top leg (reversed) runs 20' to the West. The center leg at switch #1 runs East 22'. So, the shortest run for the switches is to make switch #1 one end and loop around the top of the F and back to the South at the end of the 70' run for the switch at the other end (the other 3-way). If you can follow this maddness, you will see that my end switch is in the middle of my lite run......Since my "end" is in the center, I have to send my power to the center of my lites and then go both ways!!!!! Man I hope that makes that clear....My head hurts from all this.....
 
  #13  
Old 04-15-06, 10:50 PM
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> the shortest run for the switches is to make switch #1 one end
> and loop around the top of the F and back to the South
> at the end of the 70' run for the switch at the other end

When I followed that, I got a different result.
I'm not sure what "shortest" means here. I'm talking about total material used.
However, I don't see how my way could be any longer (just going by length of cables).


> I have to send my power to the center of my lites

That is no problem at all.


> My head hurts from all this.

Well, I'd like to see your math and/or blueprint.


I think that my way uses 30-50' more of 10/2 and 50' less of 10/3.

If you use 10/4, then my way uses 30-50' more of 10/2, somewhere around 15' more 10/3, and 65' less of 10/4.

No matter how you slice it, it saves on materials to run 10/2 to the distant west end first (how much more cable would that take? I estimated 30-50') and electricity travels less far overall in the final circuit.
 
  #14  
Old 04-16-06, 06:03 AM
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Originally Posted by Hooter
I have a hallway lighting circuit that is 600W, will be switched from 7 locations ( yea I know thats alot of 4 ways) and has a combined run length from the panel thru all the switches and to all the lights of 400' !! I was gonna use #12 but I think I should use 10-3 for all my swith legs to avoid a large voltage drop...... Could really use some help on this one........

12 Guage should be big enough. Use quality switches, you dont ever want to have a problem with this thing.

When I was a kid we lived in this huge house and everything was off the hall and the hall was dark even during the day. My dad thought about doing the same thing you are and firgured the shortest run between switches would be about 40'. We rented the house and he got permission to install wall scounches that ran almost 24/7, They were only off when the house was empty. Otherwise the hall was lit by three huge chandaliers with only one switch.

Consider a low voltage system controlling a relay
 
  #15  
Old 04-16-06, 06:47 AM
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There are a number of companies that manufacture a "master switch/dimmer" that is controllable by a number of remote units. The master unit handles the actual switching so the current carrying path from switch(s) to the fixtures can be shortened considerably. Depending on which type of master/remote system you choose, the remotes require a hot and neutral or control loop. This method allows the job to be done with 2 conductor wire and allows dimming from all locations. And, all the wire could be #14, which I prefer for lighting circuits anyway.

I have quit installing any switching that involves more than 2-3way switches that doesn't use master/remote and wouldn't even consider doing this any other way. And, you're gonna be MUCH happier with how things work.

Check Smarthomeusa.com for some options. If you call them and explain they will suggest options for you.
 
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Old 04-16-06, 07:33 AM
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bolide....... I did a double check of my math for my runs and I can save another 20' by making the oppisite ends the end switches, but I will still have to power the lites from the switch #1 location, but I do not see that as a problem. My understanding of 3-way / 4-way is that I can pull the power out of any box to the lights.

Thanks to all for the help.............
 
  #17  
Old 04-16-06, 09:05 AM
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My understanding of 3-way / 4-way is that I can pull the power out of any box to the lights.

Not unless you are planning on running a neutral in addition to all the other wire you will be running.

SERIOUSLY - get with the remote/mater setup. Less wire and simpler to hook up than the 4 ways. Just a 2 wire cable from the master daisy chained to each remote
 
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Old 04-16-06, 09:43 AM
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Originally Posted by Hooter
I did a double check of my math for my runs and I can save another 20' by making the opposite ends the end switches
Generally such is the case.

> I will still have to power the lites from the switch #1 location
If you mean the switch where the power comes in, that's correct.


> My understanding of 3-way / 4-way is that I can pull the power
> out of any box to the lights.
No, that's impossible. You can get power only from a 3-way and it has to be wired appropriately for this -- meaning that it can from from either end of the line but not both ends. You pick exactly one when you wire it (white is either the neutral or re-identified as a traveler; black is either a traveler or the common).
 
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Old 04-16-06, 11:27 AM
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Many thnks for all the help.............
 
  #20  
Old 04-16-06, 11:42 AM
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Not to stir the post or anything...

Hooter, disregard what I'm about to write, for your own sanity's sake.

You can pull the switchleg (power for the lights themselves) out of any one of the boxes, and wind up installing a four-way in that box, using only three-wire for the travellers in between switches. The tying of the switching and the box-fill get a heap-sight trickier, that's all.

(Depending on the layout of the circuit, you could even pull a switchleg from more than one of the switchboxes, too, assuming you don't mind potentially hazardous EMF, and are using non-metallic boxes and NM cable.)
 

Last edited by Rocky Mountain; 04-16-06 at 11:46 AM. Reason: Clarity, and to add last paragraph
  #21  
Old 04-16-06, 12:04 PM
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> assuming you don't mind potentially hazardous EMF

That's too big an assumption even for me to make!
 

Last edited by bolide; 04-16-06 at 06:22 PM.
  #22  
Old 04-16-06, 12:14 PM
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Originally Posted by bolide
> assuming you don't mind potentially hazardous EMF

NEC always "minds". Therefore you may not do this.
Cite a code reference.
 
  #23  
Old 04-16-06, 12:21 PM
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Not to worry...... I have it figured out and will wire lites from the 3-way box....... Now my head REALLY hurts !!!!!!
 
  #24  
Old 04-16-06, 12:28 PM
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If this were my setup to wire, I would certainly determine the shortest wire run, but I would not try to cut corners. I would use 12-4 (sometimes called 12-2-2) if I ended up with a switch loop that was only four way switches, else I would use 12-3. I would no be concerned about voltage drop, as it doesn't sound like you have that high a load.

I would worry about box fill, to the point of not only staying within code, but also using the largest boxes so that I would have plenty of room to push connections and any pigtails to the back of the boxes, well out of the way.

While you can use two pieces if 12-2 instead of 12-4 (or 12-2-2), if you have plastic boxes, doing so complicates the picture. The extra ground needs to be hooked up, and it means one more cable to run.
 
  #25  
Old 04-16-06, 01:03 PM
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> While you can use two pieces if 12-2 instead of 12-4 (or 12-2-2),
> [provided that] you have plastic boxes, doing so complicates the picture.

The colors must be marked carefuly; EMF is created regardless of box or cable materials.

Mike Holt's Power Quality article:
How does modern wiring produce elevated magnetic fields? It will not if electricians follow the Code requirement that all conductors of a circuit be run together in the same cable, raceway, conduit, cord etc.
Mike Holt's EMF article:
What kind of miswirings am I talking about? Most commonly violations of NEC sections 300-3(b) and 310-4, which require, respectively, that all conductors of a circuit must run together, ...
 
  #26  
Old 04-16-06, 04:17 PM
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Bolide, see 300.3(B)(3).

It's a practice to be avoided, but it is legal.
 
  #27  
Old 04-16-06, 06:20 PM
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The debate has been going on elsewhere, at least two other electrical forums that I see, including whether 300.3(B)(3) applies to anything other than single conductors.
Is 12-2 two single conductors?


I particularly like this note:
NEC Article 300.20 requires conductors to be grouped together to reduce heating (this takes advantage of magnetic field interaction and cancellation). It contains two exceptions. (B) prescribes a technique few people know about. In fact, when this appeared in EC&M Magazine, many readers thought it was a hoax. It is not. The technique involves cutting cooling slots in the holes through which a single conductor passes. This item has an exception and an FPN. It is worth becoming familiar with.

So it might be permitted even in the OP's case. But it will generate EMF and have a bit more voltage drop.
It depends on not using EMT or steel AC or such.

I concede that it might be allowed since you concede that the NEC cares a lot about how it is done.

I agree with that it is to be avoided even if you really do have an exception where it might be permissible. It is never necessary.
 
  #28  
Old 04-16-06, 08:24 PM
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racraft........ Most of the switch locations are 3 gang (other swithes for other lites)....... I am planning on getting the bissest box I can and since most are in 2x6 frame, I can use a deep box. So I know this is a tricky circuit for a novice, but I am comfortable with doing 3-way/4-way...... I will have it marked well and plan to fire it up before we drywall just in case. Am thinking about the 80 cu boxes with a 3 gang plaster ring for the 3 gang ones....... I wont be close to full, but will have alot of room for dimmers if I need it.......

Thanks all
 
  #29  
Old 04-17-06, 05:50 AM
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Originally Posted by bolide
It is never necessary.
I 100% agree with this "never".

Odd that Ryan voted "not legal". I'll have to look into that. Thanks for the link!
 
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