3 way switch wiring

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I have a 2.5 car garage with an array of flourescent lights on the ceiling. There is one switch by the side door which turns the lights on. I want to add a 2nd switch on a wall about 30' away on the other side of the gargage (across the 2.5 bays). I'm clear on the wiring of the 3 way switches, bought 2 & tested them at the existing switch with clip leads, my question involves the proper way to run the wire across the garage to the new switch. The garage is drywalled. My plan is to run 14/3 w/ground romex behind the drywall to the existing switch box, replacing the current switch with a 3 way. At the ceiling above this box, the wire would exit the wall, and run across the surface of the ceiling. Since the joists run perpendicular to the course of the wire, it would be a pain routing the wire under the drywall. The wire would then enter the wall across the garage and run down behind the drywall to a box I will install there with the 2nd 3 way. Easiest thing would be to simply staple the wire to the ceiling using the proper fasteners. I can't imagine a scenario where this would be a hazard or problem, but I'm not sure it would be "code", which may be an issue if I sell the place. An alternative would be to run the wire through conduit as it passes out of/into the 2 walls, and where it crosses the ceiling, which of course would add expense & work. Anyone know if the staple approach would be a code issue?
TIA
Dan
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Dan wrote:

Yes, it wouldn't be code as can't have exposed Romex in habitable space. Conduit would add some, but not a lot of work, and certainly not a whole lot of expense.
I'd wonder that there isn't attic access above the ceiling in the garage and why not simply go up there and pull the Romex where, one would presume, the existing wiring is...
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Thanks for the reply. There's living space above the garage, no attic. A garage is considered habitable space? In my previous house the garage had unfinished walls, no drywall just studs. The wire was all exposed. Same with the basement ceiling (walls were block, wiring to outlets was in conduit) A factor of its age, I guess (built mid-50's).
I have about 100' of 3/4" PVC pipe which I could use instead of the conduit. Would this be considered sufficient?
Dan
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Rules are different these days. And drilling thru studs makes a difference.

Not unless it's PVC electrical conduit. The grey stuff with appropriate markings. It's < $10 per 10' length IIRC.
[We can reduce wire burial depth by enclosing in CSA approved black flexible PVC tubing (the higher pressure irrigation stuff), but that doesn't apply here, and that's a Canadian, not US, rule also.]
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Chris Lewis,

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No.
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Doug Miller (alphageek at milmac dot com)
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Garages are not generally considered habitable spaces, however, electrical code fairly specifically addresses the use of exposed romex where it's subject to snagging. Surface mount on a garage ceiling would be normally considered to be a snag hazard.
As dpb says, plastic PVC electrical conduit is cheap and easy to work with. I used it for surface wiring on walls in a workshop, and the inspector was quite happy with it. On the ceiling, since the ceiling had lathe on it for later applying drywall, it was okay to run it parallel to the lathe across the bottom of the joists, where it had to cross lathe, I simply had to put a short length of more lathe above the existing lathe to get the wire > 1.25" away from the nailing surface.

Attic wiring has rules of its own, eg: in areas with more than 36" (IIRC) of headroom you're not supposed to have the wire snaggable (by running over the joists or under the rafters), the preferred approach is along side the joists/rafters, and going across the joist line at where the roof is lower, or protect it somehow.
Conduit is probably a whole lot easier.
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Chris Lewis wrote:

The use of PVC conduit exposed inside a building is generally a violation of the building code. The "Smoke Contributed" rating of PVC is far too high for this kind of use. Metallic conduit or Electro Metallic Tubing using factory made bends is nearly as easy to work with and provides better protection to the conductors. I would think that the simplest way to do what the OP wants to do is to install an extension ring over the existing switch box and use a knock out in the extension ring to begin a run of EMT to a surface mount switch box on the other side of the garage. If the ceiling is smooth it will only take two box offsets and two ninety degree bends to route the EMT which should make for a fairly easy wire pull. -- Tom Horne
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Oh, really?
"Type NM cable shall be permitted as follows: for both exposed and concealed work in normally dry locations ..."
[2005 NEC, Article 334.10]
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Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

But what are the restrictions on where exposed work is allowed?
My understanding which may be wrong was that normally accessible areas on finished walls, ceilings etc., wasn't allowed to be openly exposed w/o protection....somebody else noted there's alternate for high headroom that the garage might be but iiuc it still would need protection of some sort...
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Thanks for the continued input on this. The ceiling height is 8'. About 2' to the side of the straight-line path across the ceiling between the 2 switch locations is an enclosed beam about 8" wide which protrudes down 14". I could run the wire at the 90 degree junction where this beam meets the ceiling, providing additional protection. It's hard to imagine any real-life situation where a cable so located might be damaged.
I know the conduit is relatively cheap, but even at ~$1/foot it would probably add around $40-$50 to the project when all is said & done. Hardly enough to break the bank, but if it's an unnecessary expense, why spend it? ;-)
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Dan wrote:

Because it's the right way? :)
I agree there's not likely to be any safety issue but as you already noted, come time you decide to sell, you can almost count that the inspector will jump on exposed wire. While again, it wouldn't take much to fix it at that point, that's a time likely it will be even less convenient to deal with it. Besides, imo, it just looks tacky...
imo, $0.02, etc., etc., etc., ...
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PVC electrical conduit, in the size you need for a single Romex cable, isn't anywhere near a buck a foot...
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Doug Miller (alphageek at milmac dot com)
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1/2" pvc conduit is only 2 bucks per ten foot length at Home Depot.
--
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Well I guess I should actually PRICE the material before griping about it! ;-) Was expeceting more like $1/foot. I have to pick up the wire, will look at the conduit options when I do. Thanks again for all the helpful replies.
Dan
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None that I'm aware of.

The Code doesn't say that. It says, "In exposed work ... cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, [etc.]" and does *not* define any particular locations where such protection is necessary.
[2005 NEC, Article 334.15(B)]
334.15(A) requires that exposed cable "closely follow the surface of the building finish or of running boards". Seems to me that as long as it's stapled securely to the ceiling of the garage, it's compliant.

That probably depends on the local inspector's judgement of the necessity of protecting the cable from physical damage.
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Doug Miller wrote:

...
So it becomes a local inspector's opinion of whether this is "necessary" or not. Might as well go ahead and make the neat installation from the git-go, but I'll agree he _might_ get away with it...
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Pretty much, yeah, as far as I can tell.

Oh, I agree. Not much more trouble and expense, looks much better, avoids any possibility of problems down the road... but not required by Code.
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Doug Miller (alphageek at milmac dot com)
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Not explicitly required by code... ;-)
This may be of interest, from the electrical wiring FAQ
    Protection for cable in concealed locations: where NM or AC cable     is run through studs, joists or similar wooden members, the outer     surface of the cable must be kept at least 32mm/1.25" (CEC & NEC)     from the edges of the wooden members, or the cable should be protected     from mechanical injury. This latter protection can take the form of     metal plates (such as spare outlet box ends) or conduit.
    [Note: inspector-permitted practice in Canada suggests that armored     cable, or flexible conduit can be used as the mechanical protection,     but this is technically illegal.]
    Additional protection recommendations: [These are rules in the     Canadian codes. The 1993 NEC has many changes that bring     it close to these rules. These are reasonable answers to the     vague "exposed to mechanical damage" in both the NEC and CEC.]
     - NM cable should be protected against mechanical damage      where it passes through floors or on the surface of walls      in exposed locations under 5 feet from the floor.      Ie: use AC instead, flexible conduit, wooden guards etc.      - Where cable is suspended, as in, connections to furnaces      or water heaters, the wire should be protected. Canadian      practice is usually to install a junction or outlet      box on the wall, and use a short length of AC cable      or NM cable in flexible conduit to "jump" to the appliance.      Stapling NM to a piece of lumber is also sometimes used.      - Where NM cable is run in close proximity to heating      ducts or pipe, heat transfer should be minimized by      means of a 25mm/1" air space, or suitable insulation      material (a wad of fiberglass).      - NM cable shall be supported within 300mm/1' of every box      or fitting, and at intervals of no more than 1.5m/5'.      Holes in joists or studs are considered "supports".      Some slack in the cable should be provided adjacent to      each box. [while fishing cable is technically in violation,      it is permitted where "proper" support is impractical]      - 2 conductor NM cable should never be stapled on edge.      [Knight also insists on only one cable per staple, referring      to the "workmanship" clause, but this seems more honoured      in the breach...]      - cable should never be buried in plaster, cement or      similar finish, except were required by code [Ie: cable      burial with shallow bedrock.].      - cable should be protected where it runs behind baseboards.      - Cable may not be run on the upper edge of ceiling joists      or the lower edges of rafters where the headroom is more      than 1m (39").
[the last item applies to basements ceiling joists too]
....
    BX is sometimes a good idea in a work shop unless covered by     solid wall coverings.
    In places where damage is more likely (like on the back wall of     a garage ;-), you may be required to use conduit, a     UL- (or CSA-) approved metal pipe. You use various types of     fittings to join the pipe or provide entrance/exit for the     wire.
From another section:
    Note that some jurisdictions have a "no horizontal wiring"     rule in workshops or other unfinished areas that are used     for working. What this means is that all wiring must be     run along structural members. Ie: stapled to studs.
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Chris Lewis,

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Why dfon't you simply do the job in Wiremold? Any box store has it, it's neat, simple, tidy, looks professional and it's quick to install. Price is reasonable and best of, it's code! Look around in many commercial buildings, you'll see it used as a problem solver for new equipment and remodels. Odds are you've looked right at it and never really noticed. Many journeyman have it on the truck for those aggravating problems that need to be solved yesterday. HTH
Joe
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Stapling the Romex to the wall or ceiling is not to NEC. You can buy wiring channel that snaps onto the wall and optionally add additional outlets. It's easy to install and looks good.
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