Transformer Power on Large Layouts

One way that some will do it is to run a 14-12 gauge buss wire and tap off that.

It's not so much the power as it is the loss of power you get the further away.

And that loss can occur by using to long of a run with higher gauge wire like say 18 or 20 gauge.

Some will just set up power district's, you'll see a lot of that techniques in other scales running DCC.

But in general people go way over board with the amount of power in their layouts.  Keep one transformer to run the trains and one to operate accessories. And that one doesn't need to be the same wattage.

No doubt the guru's will be along to chime in.

Stay tune.

3rd Rail is right!  My Layout was 50' X 40' Long. I ran two busses, made from 14 Gauge House Wire, from one end to the other. Off that, I ran 18 Gauge feeders. I used Atlas Track and ran a new feeder every "4" JOINERS. That's where you loose Power. I could run any make of Engine and at any speed And NEVER saw a slow down.  Of course Atlas track is a good conductor & I used the 40" Pieces of Track as much as possible. I hope that helps!!

FREDSTRAINS 

I'm not a guru but have a fairly large layout.  We use 5 Lionel 180 watt Power Bricks and have ample power for 200 foot long mainlines with multiple engines.  I can easily run 7 trains at once with at least two of them being passenger trains with lighted cars.  I use Atlas track which features solid nickel silver rails with welded power feeds at reasonable distances and on each side of every switch.  I do not have any power drops.

Art  

I forgot to add: I ALSO use the 180 Watt Powerhouses thru a Lionel ZW-C Transformer!!

FREDSTRAINS

My main-line is about 231 feet.  It is divided into conventional blocks.  There are power wires, 14, that surround the entire length of this layout.  There are wire feeds no more than every twenty feet.  I use an MTH 4000Z transformer for track power ONLY.

All other turnouts, lights, accessories, sounds are evenly divided between two over CW80 Lionel transformers.

I do not lose power or experience "drops."  ALWAYS use plenty of "feeders".... 

My layout runs 53' long by about 40' wide. I ran 2 buss wires around the entire layout & drops every 10-12'. No drop in power anywhere.

I don't have what would qualify as a large layout (18' x 10'). But it is equipped to operate multiple lighted passenger trains (if I had them) or multiple powered locomotives.  The answer is blocks, or more accurately power districts.

Power districts allow you to break up your mainline into segments, each powered by a separate power source (transformer or tap).  I have 8 power districts with 2 180 watt Powerhouse bricks supplying them.  If I needed to, I could power each district individually with its own supply.  That would be massive overkill and a waste of money. 

The districts are shown below as different colored sections of track.

If you set all your transformers to the same output, then there is no "jump" when the train passes from one power district to the next. 

The other important thing to avoiding power drops is wiring.  I use 14 gauge stranded copper wire from the transformer all the way to the track.  Also, I use terminal strips.  Power (2 wires) comes from the transformer to each terminal strip where it gets distributed to a district (sections of track).  Each district can have up to 8 pairs of feeder wire to the track.

In the drawing below, look for the "TPC 400".  To the left of it is a terminal strip that sends power to all 8 districts.  Four of those districts (blocks) have terminal strips (on the left side of the drawing).  From those terminal strips, pairs of feeder wires go to the track.  The other 4 blocks (2, 3, 6, 8) go to another panel and set of terminal strips (off the top of the diagram).

The two black "blobs" at the bottom of the diagram are the PowerHouse 180s.  If you follow the wiring closely, you'll see that 4 districts are supplied by each one.  And the mainline (Blocks 1, 2, 3, 4) are alternately powered by the two transformers.  That's what keeps your voltage from dropping.

George

We have a pretty big layout  It is sectionalized into power districts  We use #12 wire from the transformers to the TIU then number 14 from the terminal blocks out to the blocks   Blocks are 25 feet long   We have no problems with voltage drops.  We do have problems propagating Command control signals however.  We use 18 MTH Z4000's, one MRC O27 max for track power.  There is about 175 - 250 feet of track on each handle. 

Buss wire is the answer for me.