Say I'm using 14 gauge for my bus, can I hook up the fixtures, specifically structure lighting to this bus? Yeah. I'm not an electrician.
Are you running DC or DCC? If DC, you will want a separate constant voltage bus, since the track voltage is variable (you increase the voltage to make the locos go faster). If DCC, you really want to rectify the signal -- yes, DCC is an AC wave, but with strange characteristics (and a digital signal imposed on it). A bridge rectifier and voltage regulator will take your track power and turn it into a nice steady power source. Or, just run a separate Auxiliary bus from a regulated power source.
I've had good luck with savaging old computer power supplies, and using them in my layout. They have 12v,-12v,5v, and 3.3v. I mount them under my layout, and use these https://www.ebay.com/itm/24Pins-ATX...007390?hash=item2ef45995de:g:eeoAAOSwl9RaGRtZ
There is a How To on just this subject http://www.trainboard.com/highball/...-pc-power-supply-instead-of-wall-warts.45036/
I have used PC power supplies before but no longer have any of that. I do still have wall warts but, am wondering if old power supplies for small model rr would work. There both rather small and I have larger, better, supply I used for N gauge. If so would I then be able to vary the volts to the accessories? It's been about 15 years since doing any of this.
Can you use 14 gauge bus wire to light structures? Sure. That's plenty big enough for a bus. You could probably go quite a bit smaller safely, but standardizing is not a bad thing. Do you want to run your structure lighting from your track power bus? Probably not. You probably want a separate constant voltage power bus for such things for a couple of reasons. As RBrodzinsky pointed out, DC track bus varies voltage all the time, and DCC track bus is... strange. Plus you don't want to use up precious amps from your track bus powering accessories. Yes. Old DC power packs can be excellent sources of fixed-voltage power for accessories and structure lighting. Be sure to use a voltmeter to measure and set the voltage, then "lock down" the knob in the right place with some tape or something.
I keep looking for grey wire with little doggys on it so I can have a grey hound bus, but no luck so far! lol
