# question for booster users



## mopac (Feb 24, 2011)

Well, I didn't get my final dream layout started this year. I have other work around the house
to do first. A deal I made with the wife. The other work is ALMOST done. Oh Boy!!!
Layout will be an around the walls layout. Room is 15' X 25'. So 80' of layout. I am putting 2
railroads (UP & BNSF) each with double mains. So 4 mainlines around the room. I bought a
digitrax DCS 200 (8 amp) command station and a pm42 so I could put 2 amps to each 
mainline. Should be plenty. Then I hear that buss lines should be under 30' in length. Mine would be 40'. I bought a DB 200 (8 amp) booster so my buss lines would be shorter. Here is QUESTION 1 - If I run 20' buss left and 20' buss right from DCC units are those 20' buss lines or are they 40' buss lines?
I bought the big digitrax power supply to run both the command station and the booster. I
woke up this morning and my first thought was how to power the booster when it will be across the room. 40 ' by layout. I don't want to buy another power supply so I will run power
wires to it. Question 2 - what size wires should the power wires be? That is a thick cable that comes with the power supply, its just very short. Thanks for any responses.


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## JerryH (Nov 18, 2012)

So you have an 8 amp command station and another 8 amp booster? The key is sizing the bus lines to minimize voltage drop. The larger the load will also be a factor. If you have a long bus line length but just a few trains, you may be able to run the whole thing with just one 8 amp booster. Teeing the bus lines from the booster keeps the length and voltage drop down. The DC power to the other booster has the same issue with voltage drop so it will need very large gauge wire and it will have to handle the full 8 amps. I would think 10 gauge would work. To keep the bus size and cost down, you may want to logically place some PM42s around the layout with the heavy bus lines to them and smaller, easier to work with bus lines from them to the feeders.


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## mopac (Feb 24, 2011)

I was planning using #12 wire for the buss lines. That should minimize voltage drop.

Yes on the 8 amp CS and booster.


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## JerryH (Nov 18, 2012)

I used 14 gauge bus lines and my longest run is no more than 20 feet from the booster through the PM42s to the end. There is a couple of feet of 18 gauge wire between the PM42 output and the bus wire terminal strip. The maximum train load is 3 sound and 6 standard decoders, in HO, per sub district on the PM42s at any one time. I don't have significant voltage drop problems anywhere on the rails other than the normal, everlasting, dirty track and wheel cleaning routines. Because of the way it was wired and the nominal loads in use, I probably could have used smaller gauge wire. You can see the wiring on pages 2 & 3.
http://www.modeltrainforum.com/showthread.php?t=14852&page=2


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## Brakeman Jake (Mar 8, 2009)

My opinion...keep it as simple as can be.Splitting the layout with a P42 is a good idea.It allows a better protection of the decoders,locomotive wheels,etc. (8 amps can induce nasty sparks) and makes troubleshooting an eventual problem much easier.

Limiting each of the four sectors to two amps. also means that you will never exceed the DCS200's capacity and the layout won't be large enough for wire lengths to be an issue so you don't need a booster.

An 18 ga. wire will easily carry a two amps. current over twenty feet.If you look at the P42's connector,that's about the larger wire size it's been designed for anyway.But,then if you fear it might not be enough,go for 16 or 14 ga. wire.

The only reason I can see you'd want a booster would be to divide your layout into more sectors,but then you'd need another P42 to stay with your two amps. limitation.

I read this type of question frequently...many worry for potential problems and want to do things right the first time...I understand.A two amps limit may occasionally cause a probem,like if you operate multiple trains (or locos) on the same stretch of track at the same time.How often it may happen...for you to evaluate,you know what you want from the layout.


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## mopac (Feb 24, 2011)

Jake, I am going to get another pm42. I also got the booster so as not to max out the CS.
The CS and the booster will not run as hot if they are each just powering half of the layout. Well unless all trains end up in the same half.


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## jabbott (Nov 30, 2014)

I had heard that limiting the buss line length was less about voltage drop and more about the dcc packets getting corrupted because of radio frequency interference.


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## mopac (Feb 24, 2011)

I heard the interference can happen at a length of 30' or more.
That's why I want to keep them at around 20'.


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