If you have an extra wire use the red and black for the switch loop. Save the white. It could be in the future yo may want a receptacle and the white could be used for the neutral then.

There's another 3-way (powered) on a different circuit (for kitchen and mudroom lighting) in the same box, and a receptacle in the same stud underneath (in my mudroom). I was concerned that in the future someone may open the box and think that the white was a neutral that was missed and try to tie it into the other circuit (or on the other end, in the garage, try to tie it into the garage light circuit).

Is it less confusing for future owners/inspector if I cap off the reds and tape the white black so they know it's hot?

Glad you take time to not butcher up your wiring but you're over-thinking it just a bit. It is not the electrician's responsibility to worry about incompetent people working in the future. Most professional electricians wire multi-gang switch boxes with often even 3 or more circuits in one box and if a clueless person decided to take it all apart without labeling the connections, they could wind up with 240 dead shorts, lights using wrong neutrals... All of that would be their own fault. Capping off the white is better in this scenario. Some electricians chose to label cables in the boxes, you could take a 2 inch piece of romex sheath and slip it over the black, red, and white wires and label it "garage light, breaker ##"

As far as inspectors, it is difficult for them to have enough time to check for 14 and 12 wire on a same circuit, make sure the kitchen has the correct circuits, see if romex through bored holes is atleat 1&1/4" from the face of the stud, much less for them to do a complete circuit analysis. Having dead ended wires in a box is nothing that would surprise them. Happens all the time with wire for a ceiling fan that ends up not using the red or switch loops wired to have an automation switch that requires a white neutral. If normal switches are used, the whites would be capped off for future use.

G

Not sure where the G at the end came from.

Thanks - got the same answer from an electrician I saw walking to his van in the Home Dep*t parking lot this AM (picking up vented soffit for porch). Sorry for the goof - of course the neutral is tied to the lights in the garage, other end just not tied to switch. That's what I get for posting before I have a cup of coffee!

I've had to fix some wiring in this house when it was built - the electrician sent his apprentice, and we had the (unused, only have 1 3-way switch at bottom of attic stairs, he never put in one at the top or for that matter no light in stairwell, just 2 sockets in attic) red from the attic light switch tied into the smoke detectors so when I flipped the switch the alarms went off. LR didn't have any power - there was a "spare" home run not labeled so he didn't connect it. Had him bring it to the box, then after we moved in I had him take the AFCI breaker off the smoke circuit and put it on the LR, but he forgot the neutral so if we plugged so much as a nightlight in the breaker tripped.

Hah, well good your able to catch these things. Not sure why you'd take the AFCI off of the smoke alarm circuit, it is required unless your locality specifically prohibits it. I see many new homes that are wired by the mediocre electricians that have connection issues. A lot of them make up boxes with all neutrals together regardless of what circuit they come from. Grounding wires are supposed to be tied together even if on different circuits yet a lot of guys screw up and keep them separated. All of which is never caught by inspectors. Too bad companies send these guys out with no experience and let them stab at it. I have guys working with me that have years of experience yet I have to constantly watch and catch nit picky mistakes. Some people just don't have the mindset of keeping track of circuitry, get too set on "black to black, white to white...." when there is a lot more to it. Really got to have the apprentice drill holes and pull wire and leave the connections to the masters (:

I knew AFCIs were required on BR ckts (house built in 2007), didn't know about smokes - is that new (I know 2008 NEC expanded it)? They ended up wiring my modular home differently than on the plans anyway as far as breaker assignment so I had to mark up plans as built. Electrician added new ckts for downstairs powder room GFI and laundry room GFI. I had them move AFCI to LR b/c I didn't know it was required on smokes (not on plans) but LR was configured to be possible ground floor MBR in future (with expansion of powder room) so I had modular factory put a smoke in there even though there is one in foyer.

I had to help apprentice pull wire for radiant heat and to change single pole for basement lights to 3-way. I should have helped (and had company pay for) him pull wire to make that switch by the door a 3-way, move the switch for the LR split receptacles from behind the LR door (not where it was on plans), move the misplaced sconce in the DR and the MBR vanity lights (ordered vanity w/o sinks/counter so they didn't bother to center over sinks) and all this stuff I have to do myself now.

I checked the attic light switch thinking it was a single pole switch with 14/3. It's a 3-way (with nowhere to go) and apprentice capped off the red, used the white (w/o taping of course) after he disconnected the other end from the smoke detector (I think - I didn't check that).

Oh, and I did check plans again - was supposed to have smokes on AFCI but I also was supposed to have 7 AFCIs and only got 6. Should we add them to other circuits (including smokes, but not garage or basement utility circuits, or the DR receptacles since one GFI on porch is connected there and we sometimes connect power tools - found out GFI on other end of porch is on LR circuit when cousin plugged his chop saw in and popped breaker) since the code has changed? I know we're not required to, but seems to be cheap "insurance".

Didn't they used to have problems with GFI receptacles on AFCI breakers?