How do I know how much track power I need when buying a DCC system? I’m not good at electrical things so 2A, 4A or 16A don’t mean much to me. I know how big my layout will be when finished and I also know how many engines will run on it.
Please explain this in a simple way.
If you know how many amps each loco pulls when running your maximum number of trains you will have your answer. I run a NCE Smart Booster(3-Amps) and have had as many as 8 locos running with as many as 4 of them pulling up a 2.5% grade(causes more draw). I have been told that my N-scale locos pull about 1/4 amp and most of the new HO stuff pull 1/3 to 1/2 depending on grade and # of cars.
So, if you are running by yourself or even one extra person the entry level systems have plenty of power for you. If you think you will have many operators with multi unit trains running you may want to consider the 5 amp systems. I have four throttles but my total draw will probably not ever excede the 3 amp limit on my system.
Electro:
The key is how many locos will be in a typical train, and how many trains will you have at a time in a single power district? Also figure sound locos take about double the amps.
Most modern HO locos only draw about .3 amps under normal operation, but a sound-equipped loco draws about .6 amps.
On my HO Siskiyou Line, a typical train has 3 locos on the head end, and 2 locos as mid-train helpers. If the locos are all non-sound, that’s 1.5 amps per train. If the locos are all sound, that’s 3 amps per train. If, as I run things on the Siskiyou Line to economize, each loco set has one sound loco, then that’s 2.1 amps per train.
Most DCC systems have 5 amp boosters. This means I can have in each booster district:
3 non-sound trains
- or -
1 all-sound train
- or -
2 “economized” sound trains.
From here you can determine where your block boundaries will have to be based on the number of trains in motion at one time. It’s also a good idea to make yards their own booster district.
This means a staging yard will be its own booster district, any on-layout main yard will be its own booster district, and then the rest of the layout will become separate booster districts based on how many trains you expect to be in motion between yards at any given time.
You should also allow for some extra capacity in booster districts to provide for that time you have really loaded down trains (meaning the locos draw more amps than normal) or to allow for an extra train more than you may have expected in typical operation.
Make sense?
spidge and Joe,
Thanks a lot. Yes that makes sense. What happens if I run too much locos in a power disctric. Do they just start to slow down or can other strange things happens?
The booster will shut down. It thinks there’s a short-circui, too much amps.
Wolfgang
Depends on how many locomotives you want to run at the same time, and if they are equipped with sound. More locos, more current draw. The current is important, as it will limit how much power will be available to the track to operate the locomotives.
Too little current and you might start running into problems like thermal shutdown of the booster, random circuit breaker tripping, etc., because the system is being taxed and can’t handle the demands you have.
You would probably be better off getting a 5A booster to begin with, and if you need more power, add boosters. You need to plan ahead for this, as you need to split the layout into sections for each booster.
Another important component is the power supply for the booster. It must supply as much current as the booster is rated for, at the least. Otherwise the circuit breaker may not trip on a short.
Depending on booster short sensitivity, the locos will either all slow down (not enough current to run them all) or the booster will see the elevated current as a short and shutdown the entire district - kabam! You won’t be able to get things running again until you pull locos off the track.
When the BLI sound locos were first introduced, their huge inrush current to charge the large capacitor on the sound decoder caused many people’s DCC system booster blocks to shut down, thinking the high current was a short. And you couldn’t get things to come back on line until you pulled the BLI loco(s) from the track – very annoying.
This is one reason why I like to break each power district up into separate train-sized blocks and protect each train-sized block with auto tail light bulbs. Using different combinations of the bulbs, you can tune your train blocks to allow just the typical train current to flow, plus about 50% extra.
With the protected train blocks, over-current shutdown of the entire booster district won’t happen, and if somebody shorts the track with a train, only that train stops running. The booster stays up and things keep running. I demostrate this principle here.
EL, if you will be running your trains by yourself, you will only be able to run three: two that you can control by manipulation, back and forth between them, running turnouts and all that, and a third running by itself on a loop. That means 2 amps will be plenty for you.
If you have a friend over, and can trust that person to run a couple of engines, then you now need close to 4 amps providing those two engines have sound and are pulling a train near 10-15 cars up moderate grades.
I have the old Super Empire Builder DB 150 that is meant for a 5 amp power supply, which I had to purchase in addition to the Super Empire Builder. I can have all 11 locomotives powered at one time, and can run three of them with no problems.
I tell you this so that you get a sense of how many amps you will need for the number of operators if more than yourself, and how many sound locos actually moving (drawing amperage, or what we also call “current”) with a train behind them.
I think most first-time modelers find that 2 amps is sufficient. For a larger layout, and more than 4 sound locos working at a time, 2 amps is close to a squeeker.
Just for comparison, I can run 10 loco’s, 2 of them with sound on my Digitrax Zephyr and its only 2.5 amps. That is with 3 operators so I would say 5 amps is plenty for most model railroaders.
A factor will also be how long the trains are you’re running with those 10 locos, and whether or not they’re on a grade. My 0.3 amps is an average of about 7 or 8 cars per loco and on no more than a 2.5 percent grade. If you’re going to be running more like 10-15 (or more) cars per loco or pulling grades more than 2.5 percent regularly, then moving to 0.5 amps per non-sound loco, or 0.8 amps per sound loco will be more like it.
Based on what TA says above, my guess is if this is HO, the cars per loco on those 10 locos is pretty low (under 7 cars per loco), and the trains aren’t on any grades.
It’s important to note there’s a difference between HO and N. N tends to draw fewer amps per loco, so don’t try to use N scale current numbers on an HO layout. Electro’s speaking HO here, I believe.
Since no one knows how many trains you’ll eventially be running be running - or the brands - including you -
Best to err on the high side. Your equpment will use only what it needs.
3 AMPS IS A CAPACITY. So is 5 amps.
Joe, it was 2 sets of 3 loco’s MUed pulling 20 some odd cars, one section of my layout has a 2 1/2 % grade that they would have to climb. The 2 sound units were doing switching duties only pulling 5 cars while the other two were passenger trains, one pulling 10 Bombardier cars and the other 6 Rapido cars. To be honest I was very surprised that the Zephyr didn’t trip out or just stop working. I have the 8 amp Super Chief ready to install and the Zephyr will probably just be used in the yard as just another throttle in the future.
I have an NCE 5 amp ProCab. I commonly run two 3-locomotive trains (no sound) pulling 60 to 75 cars with a 2% grade on the two main loops, while also running a 2 loco local with about 12-18 cars with 3% grades on the branch (which can be run continuously) and 1 or 2 locos switching the coal mine (with 2nd operater) and 2 locos working the main yard. None have sound yet. My buss is 12g solid core connected to 18g drops every 6 to 10 feet, all joiners soldered. The layout is 12x23. I have never had a shut down.
When I’m on my own, I will often run the 2 mains on continuous and take out a local and switch the branchline.