Wiring a layout for DC - How do I ensure adequate power all around?

[EastTexasBill]

I am building a point to point layout in a U shape with one leg 24' long, the other 13' with a width of 10'. This will be wired for block control. How would I go about ensuring all sections of the layout receive the same amount of "power" to the rails? In layouts past I experienced sections farther away from the power source could not power my engines adequately.

[wholeman]

You need to run two buss wires from the power pack and then run feeder wires from the main buss to the track.  You need to solder the feeder wires to the track.  If you are using flex track, you will need to do one set of feeder to every section of flex.  This will ensure adequate power. 

You might also want to place the power pack in the middle of the layout if possible.

[jeffrey-wimberly]

 Buss lines from the power pack to layout with feeders from the buss to the track? Lots of extra work for DC if you ask me. Since the layout is going to be blocked the power pack should connect to the control panel. The buss will feed into the block switches which will then feed out to the track. There should be at least one feeder connection to each block from their respective toggle switches. On even a moderate sized layout this can add up to quite a number of toggle switches. Mine is 16 blocks so that's 16 toggles, not including the ones for the turnouts. That's another dozen at least.

[fwright]

wholeman

You need to run two buss wires from the power pack and then run feeder wires from the main buss to the track. 

Not correct for DC block control wiring.

If using SPDT toggles (same as Atlas Selectors) for the block feeds, a decently heavy bus with multiple feeders will fix one side (the common side that doesn't go through the block toggles) of the circuit.  I use 16 gauge bare braided antenna wire run in a loop under my rectangular layouts.  I then connect one side of the power packs - the side I choose for common - to this single wire bus.  I habitually choose the North rail (inside of my oval) as the one I tie directly to the bus.  As was said, putting a feeder to every piece of North rail guarantees no problems with the rail joiners conducting.  That may be overkill, and you can probably get away with feeders about 6 feet - every other section of flex track.

For feeders that connect the rail to the bus or block wire, I use 26 gauge magnet wire (varnish insulation), but you may prefer the more typical 22 gauge wire for feeders.  My feeders are short, my loads are a 1/2 amp or less, and I have a feeder attached to every piece of rail.  If you use fewer or less frequent feeders, the 22 ga wire would probably be the better choice.

From the power packs to the block toggles, I normally run 18 gauge wire.  You can use heavier, but I wouldn't recommend much smaller.  From each block toggle I run 18 gauge wire to a terminal strip in the center of the block.  From the terminal strip to the rail I use the same 26 ga magnet wire (again, many would recommend 22 ga) to each section of South rail in the block.  With new rail joiners and short blocks, you can probably get away with a single feeder to the South rail in the block.  But I would again recommend installing a feeder at least every 6 feet or every other section of track.

If you use DPDT toggles with no common return or rail, the North side will have to duplicate what I described for the South rail.

Soldering joints will help the rail joiner maintain conductivity over time.  But soldering all joints may cause track problems if your wood benchwork moves with changes in humidity levels.

Unless you are running extremely heavy loads - O scale or multiple unit lashups - the wire sizes I gave will be adequate.  The test is to lay a quarter across the track at the far reaches of the layout.  If the overload indicator doesn't come on pretty quickly on your power pack, you need heavier wire and more frequent feeders.

An option instead of soldered joints and/or lots of feeders is to put short jumpers around the rail joint.

Hope this helps

Fred W

[IRONROOSTER]

 My last layout was 11 x 18 ft and used DC block wiring.  I used 18 ga wire for all of it and that worked fine as far as voltage drop.  I gapped both rails and soldered all joints within a block.  Worked fine without noticable voltage loss at the far end.

Enjoy

Paul

[jbinkley60]

EastTexasBill

I am building a point to point layout in a U shape with one leg 24' long, the other 13' with a width of 10'. This will be wired for block control. How would I go about ensuring all sections of the layout receive the same amount of "power" to the rails? In layouts past I experienced sections farther away from the power source could not power my engines adequately.

The issue of voltage drop and current over long runs is they same, whether you are using DC or DCC.  Actually, the issue is really worse for DC than DCC, since we rarely run our locomotives at full speed and thus are dealing with lower voltages. So that a voltage drop over distance becomes a larger percentage.  Sometimes, this difference between DC and DCC is offset by folks running more locomotives on DCC simultaneously than with DC.

Anyway, having said this, the solutions are similar.  Within each block you can run larger bus wires under the track and drop feeders every 6' or so to the track.  Then run the block feeds from the bus back to the toggle switches.  The good news here that is if you take this approach, the conversion to DCC, with the ability to have multiple power districts, is simple.  I actually wired my layout this way and I have the flexibility to run from 1 DCC power district per DC block or combine multiple blocks on a same power districts.  The choice is simply how many blocks I power from a DCC protection device output.