Finally ready to build my layout, electrical question

Jerry

You are planning a good sized layout and need to tell us at least roughly what your track plan will be,what kind of trains and how many you think you will be  running and type of locomotives. That will be a clue to the potential railpower load in amps or watts as well as the number of power districts needed. 

For example a lighted passenger train with one or more engines is a much higher load than a freight train with engine and lighted caboose. In designing the wire runs and the type and size of transformers, the type of powered track switches, the railpower load in amps as represented by the number of engines and lighted cars is the determining factor for wire size and transformer capacity..

Lets assume, for example, you plan on a dual mainline and a sizable freight or service Yard and will be running in Conventional control with possibility of adding Command control later. Lets define that as 3 power districts: two mains and the yard. A suggested railpower bus of #12 would consist of a Common wire and perhaps 3 #12 Hot wires, one for each mainline  loop and one for the yard. The Common would serve all districts as the "Layout Common" whereas each Hot would serve a single separate district.

This is a simple explanation of railpower needs without consideration for a lower voltage[ below 18VAC] for motorized accessory power or lighting Bus. Also if not powered by railpower a bus wire run[s]or home run wiring for track switch motors will be needed.

Terminal strips are useful for power distribution from Bus to rails. The photo below shows a "Hub and Spoke" T-strip which was one of three used to distribute railpower on a 15x 23/8x12 layout with three power districts. You can see the white, red, black and green #12 wire runs of the Bus connected at the bottom of the strip and from the same terminal screws similar wires outbound to the next Hub. The white is the Layout Common and the colored are the Hot wires for the three districts. Then, you can see pairs of #16, a white Common and Colored Hot extended out, as pairs, for soldering to rail flanges.[at one point this system was successfully modified to operate TMCC and DCS]

I have to leave now for some "honey dos" but hopefully this will not be too confusing and will trigger some layout planning before running wires. Others will likely help you out also.

Second photo on another layout shows rough wiring before cover up of a "bus" for railpower[red, black white], home run wires for Tortoise switch motors[blue, yellow], power wires for accessories[green] and lighting[brown] wire runs. 

One 12 gauge wire would be good for a 20 amp return. It should carry the sum of all amperage of all the transformers hooked to it. For a common I use 2 runs of 12-2  solid Romex house wire. That gives me a 120 amp return. I use bus bar extensions for electrical boxes shown here. 

LINK

Every thing on my layout goes to a common return. You said part of your layout is command. DCS may have signal problems if a common return is used for the track. 

If you want to activate track accessories,such as crossing flashers,block signals,etc,you should make some or all of the loop with isolated outside rail segments when laying track. If this is done simple relays can be added shown here to activate an accessory anywhere on the  layout,now or later. 

LINK2

if you use a lot of relays I recommend a separate DC system sharing a common with a separate transformer and 24VDC relays. Any starter set type will do and a bridge rectifier.

On my layout I used Quietbrace on top of half inch OSB board.

Dale H

If you're thinking of going with MTH's DCS system I wouldn't do anything just yet. It requires a little more wiring (not that much). I would wait for a track diagram. DCS  works well  with  paired wires to each block. Anyway... The heck with the wiring and more pics of the planes.

I used a bare 12-gauge common ground around my layout, and brought the far end around to the transformers, so both ends of the ground are connected.  Such a loop circuit gives greater ampacity at no cost.  I used bare wire to simplify tying everything into it.

By the way, my layout (36x16) was orignally designed for conventional, and thus has many toggled blocks.  All hot feeds to blocks are 14-gauge stranded wire.

IN 2002, I added DCS, which works fine.

All,

You guys are great. I really appreciate your help.

I plan to run mainly lionel postwar with some command control stuff ( I have 3 lionel TPC 300 s) and probably will  run two or three at most engines at one time. I will be using mostly postwar Lionel assessorie. Will be using conventional Lionel 0 gauge tubular track and 072 and 022 switches and old lionel ZWs. I am compleoneltely starting from scratch as I have never wired a layout so it will be hit and miss hopefully more hit!!!

ALL HELP WILL BE GREATLY APPRECIATED!!!!!

By the way I live in the Plymouth, Ann Arbor area of Southwest Michigan and if anybody lives close to me I would like to get together with them.

Again, much thanks, Jerry