Layout wiring can be as simple or as complex as you need for it to be. Theoretically, all you need to do is connect two wires from the booster to the track, and, except for reverse sections, it will work. But we all know that most railroads need several sets of track feeders to operate smoothly throughout the entire track plan.

Nickel silver track is not a good conductor of electricity. Further, rail joiners can create a potential for interruption of power. So, you need to have track power feeders every six to ten feet. Even so, it's still just two wires strung around the layout for feeders to be connected to the track in several places.

However, there are other things that can cause more complexity than this, such as reverse polarity sections, additional boosters to run more trains, additional boosters to isolate derailments from affecting other trains, and detection blocking for train position or signaling. But in all cases, it is always easier wiring DCC than it is for block control. The fact that you don't have to wire all those toggle switches makes this self evident.

Each booster has a certain amount of power that it is capable of providing. If you try to draw more than it is capable of, it will shut down. Usually before that, though, you will see a marked decrease in loco performance. For example, if getting close to the limit of a booster, you might see one train slow down slightly as another is starting up.

A typical Digitrax 4.5-amp booster is capable of powering about 10 HO scale locos - more if nothing but high quality locos are being run, less if all Athearn or higher drawing locos are being run.

One might think that the answer is to use a power booster that is capable of more power, or to parallel two or more together to place more power on the rails. However, placing more power on the rails can have the potential to melt things if a booster doesn't shut the power off soon enough after a derailment. And, the more power there is on the rail, the faster the power must be shut off to avoid damage. So, for train control, the advantage is to have more smaller power boosters around the layout than to have fewer power boosters that will place more power on the rails. There is a side benefit of having more boosters as well, as later discussed.

To add more boosters, all you have to do is: divide your layout (trackage) into logical divisions of however many boosters you think you will need, cut the under-the-layout track bus at logical points to accommodate the trackage split, and connect one booster to each section. The boosters are connected together through network wiring so that all boosters are sending the exact same signals simultaneously. That way, when a loco crosses the track gaps that separate the power districts, the loco never misses a beat - without toggle switches, or anything else to think about.

Something to think about is that the under-the-layout track power bus needs to be large enough to carry all of the power needs. With cab control, the wires need only to be large enough to power one train. With DCC, the bus needs to be large enough to carry all the power the booster is capable of supplying - 4.5 amps, for example with a Digitrax DB150 booster.

Something else to think about, is that everything on the rails that uses power will be getting their power from the booster. This means that if you have a fleet of lighted passenger cars, they will be drawing power too. And, if they're in the yard, they will be drawing their power from the yard booster. You could rig a toggle switch, or feed power to the yard track via a power routing turnout instead of from track feeders. This way you could turn power off to these cars when they're not in use. Some people are actually installing decoders in groups of passenger cars to have DCC control of the lighting.

In addition to this, all locos that have decoders installed will be drawing about 7 milliamps of current even when they aren't running. This isn't much per decoder, but if you have a large fleet, it could add up. Again, if sitting in the yard, it will be drawing current from the yard booster.

1. If you already have live-frog turnouts you probably already understand their special wiring needs. But if you're new at this, and laying new track, InsulFrog turnouts do not require any special wiring and therefore are much easier to use. A live frog is not needed by locos with adequate power pickup, and the power routing capabilities of live-frog turnouts are not needed with DCC.
2. Before starting your wiring job, draw your track plan in two colors - red for the right rail, and black for the left rail (I used red and black to get you used to the NMRA's color RP of red for right, and black for left). If you have a reverse section, this will make it show up without question.
3. Use two different colors of 22-24 AWG solid core wire for track feeders. You can use red and black to match your drawing. If you can't find red wire in this feeder size and track bus size wire, use white and black - explained later.
4. Keep track feeders as short as possible - no longer than one foot, but better to be kept less than 6". While this short length isn't absolutely necessary for DCC to work, it is necessary to insure reliable operation of most booster's Short-Circuit Protection.
5. Use plenty of track feeders. Current wisdom states every 10 feet. I think it shouldn't go beyond nine feet (one pair of track feeders for every three sections of flex track). Many people think it should go beyond six feet (one pair of track feeders for every other section of flex track). Some even install track feeders to every piece of track.
6. Use the same two different colors for the under-the-layout track power bus. This way, when you're under the layout connecting track feeders to the bus, you simply connect red to red (or white to white), and black to black. It's tough to make a mistake this way.
7. Solid core copper house wire makes a good under-the-layout bus. Get individual wires, not Romex that has two wires wrapped in a sheathing. This way, the two wires are readily accessible for connecting track feeders. Solid core holds it shape better than stranded wire - making for a cleaner looking bus. And, it's usually easier to strip and solder to solid core wire - it's too easy to cut a strand or two of stranded wire, weakening the wire physically and electrically. Besides that, it's dirt cheap.
8. When calculating the size of track bus wire to use, get the next size bigger than normally would be used. It will be much less expensive to use an over size than to use an under size. Wire is cheap, so using one size larger than calculated is cheap insurance. Again, this is to insure the booster's Short-Circuit Protection will work reliably.
9. If the track feeder needs to be extended to be able to reach the track bus wires, again, use the same color wire, but of a larger size than the feeder. Generally, unless the wire has to be exceptionally long (more than 8 or 10 feet), 18 AWG (solid or stranded) should be adequate.
10. If you're concerned about creating a short circuit during the bus wiring process, connect a buzzer between the two bus wires with appropriate power. This way, if you ever connect anything wrong, the buzzer will sound immediately (this tip provided by Allan Gartner).