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On the phone with a friend in Cali this morning. He said that some municipalities are requiring /4 (12-3 or 14-3 romex) wiring for all new construction or rewiring for overhead lighting components. Maybe they love the use of fans or know that in the future that the extra wire could help with energy savings when using a central lighting system.

I have personally always used /4 for this because I am always afraid that someone will change their mind and want a fan (I install a fan brace too). I am wondering if there is any code to back up the wiring requirements in different parts of the US or world and what you would offer advice as best practice?

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Why /4? /3 gives you neutral + fan + light. The only benefit /4 has is if you run power to the fixture first, you can run neutral+hot to the switch, then 2 switched hots back. If you just run power to the switch first then you only need a /3, in my mind.. Either way, running a /3 or more to anywhere that might have a fan installed is pretty handy. –  gregmac Jul 29 '13 at 17:21
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When you say 12-4 or 14-4, are you counting the ground? –  bib Jul 29 '13 at 17:36
    
Yes counting ground - B/W/R/G. –  DMoore Jul 29 '13 at 17:47
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I believe the convention is to describe NM wire (often called by the brand name Romex) by the number of wires excluding the ground. 14 gauge B/W/G is referred to as 14-2 and B/R/W/G is referred to as 14-3. –  bib Jul 29 '13 at 18:14
    
@bib yes. I think that applies to any line-voltage cable, as it definitely does for BX (armoured) as well as NM. It definitely applies to any line-voltage you'll use residentially. Does not apply when you are talking about low-voltage signal cable (alarm, speaker, HVAC, etc) as they don't have a dedicated ground. –  gregmac Jul 29 '13 at 18:16

2 Answers 2

I think you may be referring to the addition of item C to section 404.2 in article 404 of the National Electrical Code (NEC). Which states...

National Electrical Code 2011

ARTICLE 404 Switches

404.2 Switch Connections.
(C) Switches Controlling Lighting Loads. Where switches control lighting loads supplied by a grounded general purpose branch circuit, a grounded circuit conductor shall be provided at the switch location.

Exception: The grounded circuit conductor shall be permitted to be omitted from the switch enclosure where either of the conditions in (1) or (2) apply:

(1) Conductors for switches controlling lighting loads enter the device box through a raceway.

(2) Cable assemblies for switches controlling lighting enter the box through a framing cavity that is open at the top or bottom on the same floor level, or through a wall, floor, or ceiling that is unfinished on one side.

The intention of this code change is to provide a grounded (neutral) conductor in switch boxes, so "smart" devices can make use of it.

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Do you know of any places enforcing this. An inspector I mentioned this to today that was looking at a basement I am redoing looked at me like I was smoking something... He's like well you can if you want but we don't require it. –  DMoore Jul 29 '13 at 21:30
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Any place that has adopted NEC 2011 should be enforcing this. –  Tester101 Jul 30 '13 at 10:43
    
@Tester101 Some inspectors take the view that it's the code as of the date of the work (regardless of the date of inspection). When I needed a C of O for a house I was selling that had old, uninspected renovation, he applied the code as of the renovation date (it was all good, safe work - biggest difference - battery, not hard wired smoke detectors). –  bib Jul 30 '13 at 15:15

The extra cost of 14-3 over 14-2 seems to be between 30% and 50%. However the cost of these materials is relatively small compared to the overall labor costs.

The costs of adding an additional line as old work is significantly higher that the small cost of the wire premium installed as new work. The only other downside is that 14-2 is easier to handle than 14-3. Again, when doing new work, that handling is not so complicated compared to old work. (12-3 is especially painful to snake through old work walls and blind curves.)

Putting a spare hot lead in fixtures gives you significant flexibility for both multiple devices, such as a fan/light combo, the possibility of more sophisticated switching, such as 3-way and 4-way, and the possibility of adding switched and unswitched outlets beyond the fixture.

As Tester101 points out (and as mfarver alerted me to last week), the code now requires a neutral at switch boxes, specifically to make it easier to accommodate future active components, even if the current intent is a dumb switch that does not presently need a neutral.

I do not know if any local codes require the extra hot line at fixtures, but is seems like cheap insurance for future possibilities. It sounds like a best practice to me.

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