when starting a dcc wiring,whats the first consideration? I dont know if you should consider breaking up the layout into power districs as soon as the wireing is started or wire the main to see if all the track is ok,and then wire as you progress into the track laying? OPINIONS.......Booyak.........

Here comes that answer you probably hate to hear: It all depends. It depends on how big your layout is. How many trains you plan to run at once? What are your powere requirements? Are you using a buss line or going star pattern? I'm sure there are more questions others will have.

Based on an analysis of the layout plan from an operations point of view, I chose to divide and wire the layout into 4 power districts. For initial DCC operations/testing I've temporarily connected the buses for the 4 districts together behind one Power Shield fast acting breaker, which in turn is powered by one 10 amp NCE booster. I've ordered 3 more power shields and will install one for each power district - all 4 powered by the initial single booster. I'm using a TTX digital RampMeter to accurately monitor the total current draw on the booster. If I see power demands getting close to the 10 amp rating of the single booster, I'll purchase and install additional boosters.

Ed Rappe

Ed, would you please tell a little more about the Power Shield breakers? Is that a brand name?

Chris
Power Shield breakers are solid state fast acting/self resetting DCC circuit breakers. They are sold under the DCC Specialties brand by Tony's Train Exchange. Other manufacturers offer similar DCC breakers. They are offered in the PSX –n series of products, with PSX-1 being for one block (or power district), PSX-2, for 2 blocks, PSX-3 for three blocks, and PSX-4 for 4 blocks etc. Check out the TTX web site for info and pricing on the PSX series of breakers, and many other DCC devices (such as auto reversers and digital current/voltage displays. Tony's Train Exchange

For multi train operations on a fair sized layout, it is a good idea to subdivide the layout into power districts - even if you are operating below the current threshold of your booster. That way if engineer A runs his locomotive into a closed turnout causing a short, it doesn't kill trains running in the other power districts. While boosters have internal breakers, I've found the PSX breakers to do a better job of responding to shorts - and its allot less expensive to use one Power Shield per power district than one booster per power district.


Ed Rappe

PS I've found Tony's web site to be a valuable source of DCC info

Thank you Ed, for the description.
It is an efficient means to district a layout, maximize capacity of a booster, and protect components.
I use the RampMeter myself for my test track. I'll check out TTX.

For district design, is it based on logical breaks in the layout geography, or an even distribution of layout electrical loads?

Something I was told when I wired for dcc was that when operating, if a derailment or short occured, you wanted to separate it so it would not bring other trains to a crashing halt. So if you have a switching yard for instance, separate that from the main incase of a short. They could still be on the same transformer.
If your running large consists and lighted cars that would mean more power requirement. That might include breaking the mains so that two trains would not be on the same power district at any one time. Maybe two mainline loops would each be a separate loop for separate trains, or a really large mainline broken up, etc. They would use separate breakers and power sources. Joe

Chris - a little of both.

My power districts are:
1- Middle Division (3 track river grade running)
2 - Altoona yard (classification tracks and engine terminal tracks (excludes through and arrival/departure tracks)
3 - Pittsburg Division (4 track helper district around Horseshoe curve)
4 - Tyrone and Clearfield Branch (single track heavy grade - minimal trackage in at this time)

Initially I started with all the districts behind one booster and 1 PSX1 power shield just to test things out (retaining a DC option via a DPDT toggle)

Next I connected districts 1 & 2 and 4 behind a single PSX and 10 amp NCE booster, with district 3 is on a second PSX and 10 amp booster.

After an open house in a couple of weeks, I'll split off the yard onto its own PSX1, but still sharing a booster with the Middle Division and the very small piece of the branch that is in operation.

When the branch (Power district 4) is further along, the first step will be to put it behind its own PSX1 circuit breaker. I'll monitor current draw during operating sessions and if I'm getting too close to the 10 amp rating, I'll buy a third booster just for the branch.

I'm approaching this incrementaly from a PSX/booster purchase perspective, but wiring in a way to make later change easy. I use AWG12 wire for the busses and so far haven't had any voltage drop issues. My longest buss run from a PSX/booster is about 120'.

I envision having a max of 5-6 cabs in operation at any one time (I don't do loop running). The heavy power draw will be 3-4 locomotives on trains westbound around the Horseshoe Curve (2% grade). Typical freight is 30-35 cars, passenger is 10-12 cars. The mail and express train is 22 cars. Upgrade current draw for a diesel freight (ABA OM sharks) or 12 car Broadway (AA OM E8) is showing at about 3 amps/train. My passenger cars are running without lights until I install LEDS (its perpetual daylight on my railroad for now).

I think the recommendation I got from Tony (at TTX) was sound, don't over power the layout until you have solid operational experience on how much power you'll actually need - DCC boosters and 10 amp transformers aren't cheap!

Ed Rappe