Getting Ready to Wire Main and Accessory Bus'

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rvnmedic6869

New Member
#1 - my layout is on a 5' x 16' table.
#2 - the track layout right now is rectangular, with the Main going around the rectangle and the Sub branching off of it and paralleling the Main for 3/4 of the Main.
#3 - I'm following the DCC wiring info from DCCWiki and the Wire Gauge Guidelines for a DCC Power Bus and also power drops specs.
#4 - I have an MRC Prodigy Advance2 power station and Cab throttle
#5 - I plan on wiring the Main Bus in a long loop that will be about a foot inside from all the edges of the table with 14 AWG- Is this a good idea?
#6 - I plan on wiring the Accessory Bus inside the Main loop, about a foot in from the Main (~ 2' from all the table edges) with 22 AWG - Is this a good idea?
#7 - I plan on putting Wall Warts on both ends of the table.
#8 - I plan on connecting the MRC power on the middle of the long edges to the Main Bus.
#9 - I plan on power drops to the 3 non-powered turnouts to insure power routing through the Peco Electrofrog turnouts (each is gapped right now to prevent a short.

Note that I say "I plan". Please advise if any or all or none of the above is a good idea. Keep in mind this is a new layout on a new table put together by a 73 y/o "newbie" whose last train layout was my son's DC HO setup 40 years ago.

Rough picture as the track layout was in progress recently. You can see the small gaps just left of the frog:

1612641358432.png

Power routing for the turnouts(my gaps are in place of the insulated rails)
1612641572761.png
 

Attachments

flyboy2610

Loveably weird
It all sounds workable, but do not connect the two ends of the bus together, as though forming a continuous loop. Just let each end of the bus wire's terminate. You can put a wire nut on the end of each wire if you wish, but that's not really necessary.
22 gauge sounds a bit light for the accessory bus. Do you have enough 14 gauge wire to do that one as well? Even 16 gauge would work fine.
 

rvnmedic6869

New Member
It all sounds workable, but do not connect the two ends of the bus together, as though forming a continuous loop. Just let each end of the bus wire's terminate. You can put a wire nut on the end of each wire if you wish, but that's not really necessary.
22 gauge sounds a bit light for the accessory bus. Do you have enough 14 gauge wire to do that one as well? Even 16 gauge would work fine.
If I use two separate bus lines, I assume I should connect the MRC power to one and then a shunt from the bus line over to the other? I envision two bus lines running the length of the table as mentioned in my OP and the shunt or connector to the other in an "H" shape?

I believe I do have enough 14 gauge to use for the accessory bus. And if I don't I'll get more.
Re the accessory bus, should I run two of them parallel to the two main bus lines with drops to the Main at each end?

Thanks for your help!
 

Selector

Well-Known Member
Not sure what you have in mind from your last post...the 'shunt'. Each PAIR of bus wires should be separated, even if paired. The only 'shunting' takes place inside the decoder and the can motor driving the locomotive. Otherwise, there is never any connection between the two wires comprising a 'bus'. As stated by flyboy, just tuck the ends of each pair of wire APART, but close by, capped with tape or a wire nut. Never allow or make the wires touch each other.

This would apply to an accessory bus, and for the same reasons that the three wires inside a wall socket never touch. The circuit is complete through the powered item and then back to ground. That's what the decoder and motor do. NOT the wires anywhere along their lengths, including the very tips.

I typically run my buses two ways, like a T. The vertical stem is the feed from the DCC main controller/output, and the top of the T is the pair of bus wires going two ways so that none of them is longer than the extremes of the run they must make. Any wire above 16 gauge will suffice for runs of about 20', but longer than that you should be using 14 gauge or thicker. 12 gauge is overkill for the vast majority of requirements for layouts, but if you have some unused, go ahead, by all means.

For your item #9, if you gap the Pecos, and feed them only from the points end, you'll have to power what lies beyond them, gapped as you describe, with their own feeders. You probably understand that already.

Note that the run of the main bus only needs to approximate the path of the tracks above them. The idea is neatness, organization, minimizing expense of copper wire by making the runs short, and also reducing the lengths of the narrow gauge feeder wires so that voltage drop is minimal...and cheap.
 

rvnmedic6869

New Member
Not sure what you have in mind from your last post...the 'shunt'. Each PAIR of bus wires should be separated, even if paired. The only 'shunting' takes place inside the decoder and the can motor driving the locomotive. Otherwise, there is never any connection between the two wires comprising a 'bus'. As stated by flyboy, just tuck the ends of each pair of wire APART, but close by, capped with tape or a wire nut. Never allow or make the wires touch each other.

This would apply to an accessory bus, and for the same reasons that the three wires inside a wall socket never touch. The circuit is complete through the powered item and then back to ground. That's what the decoder and motor do. NOT the wires anywhere along their lengths, including the very tips.

I typically run my buses two ways, like a T. The vertical stem is the feed from the DCC main controller/output, and the top of the T is the pair of bus wires going two ways so that none of them is longer than the extremes of the run they must make. Any wire above 16 gauge will suffice for runs of about 20', but longer than that you should be using 14 gauge or thicker. 12 gauge is overkill for the vast majority of requirements for layouts, but if you have some unused, go ahead, by all means.

For your item #9, if you gap the Pecos, and feed them only from the points end, you'll have to power what lies beyond them, gapped as you describe, with their own feeders. You probably understand that already.

Note that the run of the main bus only needs to approximate the path of the tracks above them. The idea is neatness, organization, minimizing expense of copper wire by making the runs short, and also reducing the lengths of the narrow gauge feeder wires so that voltage drop is minimal...and cheap.
I shouldn't have used the word "shunt". I meant a connection between the two main bus wires running parallel the length of the board - 16')) that I thought I needed. From what you are saying, it sounds like I don't need two main bus wires running the length of the 16'? Just one long 16' down the center of the table and the accessory bus parallel to that? The feeder wires from the center of the table wouldn't be longer than 3' either direction (left or right). And yeah, I will wire the turnouts as in the diagram in my OP above with drop feeds down to the main bus.

I've seen so many different ways of wiring by people on the board and also YouTube videos. I like to keep things simple and organized like you mentioned. Thanks for the reply.
 

Selector

Well-Known Member
Terminology is sometimes the thing that trips us up. I'll try to be more clear:

The bus is the first and main carrier of electricity, and it should terminate near the end of a loop, where a T run's ends come back around and get close to each other. The fed end of the bus connects to the output terminals on the main DCC station. The main bus should probably be 14 gauge, perhaps as little as 16 gauge if it won't have to run more than maybe 20' from the output terminals on the main station. Some of us use 12 gauge, but it's unnecessary. It might just be that we have some of it lying around.

The bus always comprises two wires, a pos and a neg if DC, or the pos and ground that is the AC. There is no reason to 'shunt' between them.

In some cases, it is a good idea to have a sub-bus or more. You tie a sub-bus into the main bus wherever it makes sense to do that, and the purpose of the sub is to feed a major district or component of your layout, say a rather substantial yard or a large industrial complex. On a very large layout, it is often a good idea to have a booster there. The booster takes the DCC signal and 'boosts it', and it emits it at full voltage again.

If your feeder wires are in the 22 gauge range, then lengths of even 4' are fine, provided you're not likely to have something like 5 amps course through it for more than a few seconds if there's a hard short. Very thin feeders that are also quite long, say 5', and that have more than 5 amps go through them will heat up rather quickly, melt their insulation, and possibly start to burn something.
 

flyboy2610

Loveably weird
For a 5 x 16 foot table, you can run your bus as a pair of wires running the length of the table. For the DCC power bus, run it about the middle of the table. This will keep the feeder wires equal length on each side of the table. For the accessory bus, run a pair of wires down the length of the table about 12-18" away from the DCC bus. It doesn't matter which side of the DCC bus it's on. Now you have two pairs of wires running the length of the table 12-18" apart from each other. These are your buses. Keep the command station 8 feet from each end of the table, that way the DCC signal only has to go 8 feet in either direction. Run two wires from the command station to the DCC bus. Connect your DC power supply to the accessory bus the same way.
Personally, I don't like connecting feeder wires directly to the DCC bus. That makes a lot of connections, and things get real cluttered real fast! I prefer to create a sub bus using terminal blocks.

These are available in different sizes, from 4 terminals up to 10. Using a 6 terminal block as an example, I will connect 3 top terminals on each side using a piece of 18 gauge solid wire. This gives me two 'polarities' on the same terminal block. Make sure they not connect in the middle of the block! Using a spade connector,https://www.menards.com/main/electr...487-c-6447.htm?tid=2975918649895664372&ipos=4 I will run a piece of wire the same gauge as the bus from the terminal block back to the bus. Using spade connectors I will then run my feeders from the terminal block to the track.
Here's a pic to help show what I mean.
017.JPG


That's a 6 terminal block in the pic. I prefer to do it this way because it keeps the bus uncluttered, and if something needs to be removed it's a simple matter of removing the wire form the terminal block.
I do the accessory bus the same way.
Hope this helps!
 

rvnmedic6869

New Member
For a 5 x 16 foot table, you can run your bus as a pair of wires running the length of the table. For the DCC power bus, run it about the middle of the table. This will keep the feeder wires equal length on each side of the table. For the accessory bus, run a pair of wires down the length of the table about 12-18" away from the DCC bus. It doesn't matter which side of the DCC bus it's on. Now you have two pairs of wires running the length of the table 12-18" apart from each other. These are your buses. Keep the command station 8 feet from each end of the table, that way the DCC signal only has to go 8 feet in either direction. Run two wires from the command station to the DCC bus. Connect your DC power supply to the accessory bus the same way.
Personally, I don't like connecting feeder wires directly to the DCC bus. That makes a lot of connections, and things get real cluttered real fast! I prefer to create a sub bus using terminal blocks.

These are available in different sizes, from 4 terminals up to 10. Using a 6 terminal block as an example, I will connect 3 top terminals on each side using a piece of 18 gauge solid wire. This gives me two 'polarities' on the same terminal block. Make sure they not connect in the middle of the block! Using a spade connector,https://www.menards.com/main/electr...487-c-6447.htm?tid=2975918649895664372&ipos=4 I will run a piece of wire the same gauge as the bus from the terminal block back to the bus. Using spade connectors I will then run my feeders from the terminal block to the track.
Here's a pic to help show what I mean.
View attachment 124411

That's a 6 terminal block in the pic. I prefer to do it this way because it keeps the bus uncluttered, and if something needs to be removed it's a simple matter of removing the wire form the terminal block.
I do the accessory bus the same way.
Hope this helps!
"Run two wires from the command station to the DCC bus. Connect your DC power supply to the accessory bus the same way.
Personally, I don't like connecting feeder wires directly to the DCC bus. That makes a lot of connections, and things get real cluttered real fast! I prefer to create a sub bus using terminal blocks."

Okay, I followed this up until the accessory bus (aka "Sub Bus"?). If powering this bus with a DC power supply, that wouldn't have DCC signals then, right? Re the Acc Bus terminal blocks, do you use multiples spread out so the feeders aren't over 4' long? I think I've looked at too many wiring diagrams! LOL
 

Greg@mnrr

Section Hand
While what rvnmedic6869 suggested will work....but I prefer having a DCC bus and connect the feeders directly to the buss using Suit Case Connectors. This makes it easy to follow the wiring from the buss line to the track to make sure your feeders are connect to the correct rail. Using terminal strips you can get confused when connecting the feeders.

I like red wire for the right rail feeders and white for the left feeders and don't use these color wires for any other purpose under the layout.

I do use terminal strips for accessory wiring like switch machines, lighting, LED's and special effects.
Greg
 

flyboy2610

Loveably weird
"Run two wires from the command station to the DCC bus. Connect your DC power supply to the accessory bus the same way.
Personally, I don't like connecting feeder wires directly to the DCC bus. That makes a lot of connections, and things get real cluttered real fast! I prefer to create a sub bus using terminal blocks."

Okay, I followed this up until the accessory bus (aka "Sub Bus"?). If powering this bus with a DC power supply, that wouldn't have DCC signals then, right? Re the Acc Bus terminal blocks, do you use multiples spread out so the feeders aren't over 4' long? I think I've looked at too many wiring diagrams! LOL
I do the same for each power bus. Run two wires from the command station to the DCC bus. Run two wires from the DC power supply to the accessory bus. So each bus is powered by it's own power supply, they do not and must not mix! At various points around the layout, I install the terminal blocks, and from each half of the terminal block I will run a wire back to the bus, whether DCC or DC. Again, each power supply must feed terminal blocks dedicated to EITHER DCC or DC. They cannot and must not mix. From a DCC terminal block run your feeders. From a DC terminal block run power to your accessories.
 

rvnmedic6869

New Member
I do the same for each power bus. Run two wires from the command station to the DCC bus. Run two wires from the DC power supply to the accessory bus. So each bus is powered by it's own power supply, they do not and must not mix! At various points around the layout, I install the terminal blocks, and from each half of the terminal block I will run a wire back to the bus, whether DCC or DC. Again, each power supply must feed terminal blocks dedicated to EITHER DCC or DC. They cannot and must not mix. From a DCC terminal block run your feeders. From a DC terminal block run power to your accessories.
Any suggestions for the DC power supply? Voltage? Transformer type? Thanks.
 

flyboy2610

Loveably weird
Any suggestions for the DC power supply? Voltage? Transformer type? Thanks.
I used a computer power supply for my layout.
Computer power supply for layout power | ModelRailroadForums.com

Depending on what you need to power, it could be just right or it could be overkill. I'm going to have quite a few Tortoise switch machines, so the 12 volt output is perfect for those. For building lighting the 3 volt output is just right. If you have an old computer lying around that has a good power supply, as McCloud used to say: "There ya go!" If you go this route, you'll have to make separate buses for each voltage level, one for 12 volt, one for 3 volt.
You could also use a 12 volt power supply and use a what is called a buck board DC DC 9V 12V 24V 36V To 5V Step Down Board 5A 4 USB Output Buck Converter Power Supply Module with Aluminum Shell For Phones|Integrated Circuits| - AliExpress to drop the voltage as needed. I don't really have a recommendation for a 12 volt power supply. If you plan to use under track Kadee electromagnets, they require a 16 volt power supply, so keep that in mind.
 
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rvnmedic6869

New Member
I used a computer power supply for my layout.
Computer power supply for layout power | ModelRailroadForums.com

Depending on what you need to power, it could be just right or it could be overkill. I'm going to have quite a few Tortoise switch machines, so the 12 volt output is perfect for those. For building lighting the 3 volt output is just right. If you have an old computer lying around that has a good power supply, as McCloud used to say: "There ya go!" If you go this route, you'll have to make separate buses for each voltage level, one for 12 volt, one for 3 volt.
You could also use a 12 volt power supply and use a what is called a buck board DC DC 9V 12V 24V 36V To 5V Step Down Board 5A 4 USB Output Buck Converter Power Supply Module with Aluminum Shell For Phones|Integrated Circuits| - AliExpress to drop the voltage as needed. I don't really have a recommendation for a 12 volt power supply. If you plan to use under track Kadee electromagnets, they require a 16 volt power supply, so keep that in mind.
It would be used primarily for fiber optic lighting and any other mechanical accessories. Will check out the link you included. Thanks!
 

Iron Horseman

Well-Known Member
Personally, I don't like connecting feeder wires directly to the DCC bus. That makes a lot of connections, and things get real cluttered real fast! I prefer to create a sub bus using terminal blocks."
On a 5x16 layout how many feeders do you expect to have?
 

rvnmedic6869

New Member
On a 5x16 layout how many feeders do you expect to have?
Ah, I was quoting flyboy2610 in comment #8. With the research into DCC wiring, I was going to go with dropping track feeders and turnout feeders onto the DCC bus. But, I also like the idea of an accessory bus too.

Right now I'm projecting feeders for the (12) 3 Peco Electrofrog turnouts (for power routing only - not for switch machines), and maybe 3 or 4 feeders for track power along the 16' board. So, 15 or so feeders possible. I will not be setting up power districts at this point. May add them later on.

And that brings up another subject of setting track feeders at various points. I've seen it on youtube vids (by well known MRR folks) and in the Basic DCC Wiring Book by Mike Polsgrove. I'd rather not get into that on this thread - might only add some confusion into it? Also read about soldering the rail joiners. How many and how far apart seems controversial.

So, I think right now I need to get the bus wiring choice made.
 
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