Given the option, is it better to bring power to your switches first, then run wires to your lights? Or is it better to bring the power to your lights first, then run wires to your switches? Or does it matter?
For new installations, the important thing is really getting neutral to the switch location.
- NEC requires it (in most cases) as of the 2014 edition
Chapter 4 Equipment for General Use
Article 404 Switches
404.2 Switch Connections.
(C) Switches Controlling Lighting Loads. The grounded circuit conductor for the controlled lighting circuit shall be provided at the location where switches control lighting loads that are supplied by a grounded general-purpose branch circuit for other than the following [...]
- It allows you to use more advanced switches (timers, motion sensor, lighted, and/or 'smart' switches)
To get a neutral to the switch you generally either need to:
- Run power to the switch first
- Run a 3-conductor (eg 14/3) between the switch and power location (carrying neutral, hot, and switched-hot).
Given 14/3 is more expensive than 14/2, in most cases, I'd say run power to the switch first unless it's substantially father away from the power source than the lights (eg: the power-supplying wire passes your lights, then you have to double back with power to the lights).
If you only have a couple situations where you need this, it may not be worth it to buy a spool or some bulk 14/3, so it's ultimately a judgement call.
The question of "is it better" was actually determined by what the NEC code says. In a nutshell... the hot or supply wire needs to run into the switch box WITH its mated neutral wire first. The reasoning is that many of the new switches have circuitry in them that require a neutral and "end running" the switch doesn't provide that. Technically, and for liability purposes, if you touch it, it MUST be brought to code. However, in the scenario you brought up, all of that will be determined by exactly where that circuit is fed from. If you are doing a 3 way switch, and following code, it has to be in one of the switch boxes. The outlet for that circuit can be tapped out of the box that has the hot but that hot won't be in a light fixture box.