I've heard all about power busses on DCC and saw videos on it. What exactly is it and what does it do?
Andy,
A DCC 'power bus' is usually a pair of heavy gauge wires(12-18 gauge) that follow the main line around from 'under' the layout. Feeder drops from the track to the power bus are usully something like 20-22 gauge wire. The idea is to provide a low resistance path so you are not depending on rail joiners for electrical contact. This is a good idea even with DC layouts. Most DC layouts have some pretty poor wiring at best. This was not a big issue as only the power for one set of engines was on the block wiring with DC cab control. With DCC layouts, full voltage and full current(5-8 amps many time) may be flowing. My home layout has #14 'bus' wiring, and the club has #12 'bus' wiring. A voltmeter test on either layout show no voltage loss, even with 25' bus runs. A quick check is to press a quarter to the rails and see if the command station/booster trips it's built-in breaker. If it does not trip, you have a problem. The current carrying capacity of a DCC layout is a safety issue - use good wiring practices. Do not believe the LHS guy who told you DCC is so simple that you just hook two wires to the track! My layout is broken into 8 blocks(signaling) and I used about 200 feet of #14 red & black wire. Most layouts would use far less. Residential wiring from Lowes/Home Depot/Menards is inexpensive.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Basically, a power bus is the (usually heavy) wires that run from whatever is supplying the power to a series of devices using that power.
In model railroad terms, it's the wires, commonly 12 or 14 gauge, that run from your DC power pack or DCC booster under the layout, with feeders going to the track every so often.
Most rail is not really a very good conductor of electricity, so the voltage will drop at the far ends of the layout. Using a heavy-enough gauge of wire helps prevent that from happening.
Steve
Here are some links to the subject and an example how you can use Google to search for information.
http://www.google.com/search?hl=en&ned=us&q=dcc+power+bus&btnmeta%3Dsearch%3Dsearch=Search+the+Web
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.