# DC/DCC Bus Wire Question



## Bwells (Mar 30, 2014)

I have an around the wall layout which has a 14 AWG solid bus that falls short of connecting by 5 feet. The track feeders are 22 gauge solid and spaced every other stick of flex and all joiners are soldered. I have two cabs, DC and DCC that connect to the bus 10 feet from one end yet 40 feet from the other end. Would it be wise to complete the circle and is there any advantages to doing so? I have not checked for voltage drop on the long side but I doubt there is any, I was thinking the unbalance between the two legs could be a problem with the DCC side. I have no problem connecting the circle but it would be with wire nuts and they are ugly and soldering two 14 AWG wires and heat shrinking them is scary! Thanks, Brian


----------



## Brakeman Jake (Mar 8, 2009)

You shouldn't have any noticeable voltage drop with 14 ga. wire,even over forty feet,unless you'd run a large number of trains all at the same end at the same time...unlikely.
As far as closing the loop (bus wires),Digitrax recommends not to do it as it complicates finding problems should you have any.However,if you fear an "unbalance",you could try to move your command station closer to the center of the circuit.

Installing both a DC and DCC cabs to the same trackage is asking for problems...make sure you have a DPDT switch between them so that they can't both power the track at the same time.These two can't be connected together even when they're not both turned "on".


----------



## Bwells (Mar 30, 2014)

Yeah, I have DPDT center off switches to control the cabs and the main is only used for one or the other. I'm using NCE power cab but I can't move the Cabs to a different location. I maybe thinking to hard on this one but I am trying to finish some wiring and when I ran across this question I thought I would ask. I assume my track connections should take care of any problems with the track bus but not sure. Thanks for the reply, Brian


----------



## DonR (Oct 18, 2012)

Brian

I Want to emphasize what Jake said. Do NOT
make a complete circle of your DCC Buss.

As a matter of fact, you may want to
consider adding a snubber at the end of
that 40 foot buss.

Wiring for DCC and others recommend this.

Here is a link that discusses snubbers.

https://sites.google.com/site/markg...t-practices/wiring-planing/snubbers-rc-filter

Don


----------



## Bwells (Mar 30, 2014)

Thanks Don and Jake. My first thought was that it would not matter what I did but I am now glad I asked the question. The link was WAY over my head but I do know how to build the resistor/capacitor circuit so I guess it's off to Radio Shack for the 2 components (if it is still there). I still don't understand putting a short between the 2 conductors but as the saying goes, "yours it not to reason why, yours is just to do or blow stuff up", something like that.


----------



## Mark R. (Jan 26, 2013)

I ran my bus into a closed loop when I first installed it some twenty years ago - mainly because I didn't know any better at the time. And you know what ? .... it's still connected in a closed loop to this day and I've never experienced any negative problems because of it.

If you think about it, there are all kinds of closed loops in your wiring. A section of track and bus between a pair of drop-feeds creates a loop within itself. Every pair of drop-feeds creates a loop between the track and the bus. You would think all those potential loops would cause more problems than just tying the bus back into itself !

Personally, I think the "rule" for not connecting the bus back onto itself (as long as it is in phase) is a bit over-rated ....

Mark.


----------



## roofintrash (Jan 11, 2015)

Not to hijack the thread but have a buss ? I'm still in the planning stage but want to get all my ducks in a row. I am going to have an 8 track staging yard on a lower level and was wondering if its acceptable to run a single pair of buss wires under it and drop feeders from all the tracks,or do I need busses for each track? 
I was thinking the pair down the middle would be fine but figured it can't hurt to ask.

Rick


----------



## Bwells (Mar 30, 2014)

roof: Assuming you are using DCC, then a single buss should do with feeders to each track however if you want to turn the power off to each track, you would need a panel with 8 switches. The buss would feed the panel and each track would have home runs to the switches. That is how I would do it. For DC, definitely a panel.

P.S. Welcome to the forum.


----------



## DonR (Oct 18, 2012)

Mark R. said:


> Personally, I think the "rule" for not connecting the bus back onto itself (as long as it is in phase) is a bit over-rated ....
> 
> Mark.


It does seem like an Alice in wonderland way of doing things. I've tried to follow
the reasoning with Alan Gartner and the Wiring for DCC gang. They get into
some top pay grade stuff. I have one buss that may get to 20 or 30 feet. It
just ends there and I don't have any DCC problems. The main track is one great big
loop with no isolated sections and I have no DCC issues. Some of the discussion
has centered on cross talk and reflected digital images confounding decoders.
So it's all up to each modeller...to snub the snubbers or not...hey...we're here
to have fun.

Don


----------



## Brakeman Jake (Mar 8, 2009)

In theory,looping the buss wires shouldn't be the cause of any problem.However,I can only guess that if Digitrax recommends NOT to do it,there's likely a technical reason behind this.I like to think that Digitrax's techs know something I don't.

There's also another theory I read about,saying it's a good thing to twist buss wires together between connections to help prevent magnetic interferences between buss wires and trackage.Here too,my knowledge doesn't allow me to argue the pros and cons.One thing I'm sure though...it can't hurt.

My layout is too small for me to worry about either way,so I don't and I don't have any issues...yet.However,I firmly believe Digitrax's recommendation that DCC components should be linked to a good "earth ground" wich I did.My guess is that it should take care of any interference,should there be any.


----------



## DonR (Oct 18, 2012)

Jake

I do understand the 'twisted pair'. With one wire UP then next 
Down and the other wire the inverse of that they are cancelling out
any inducted energy. One reason for it is to reduce any 'static'
on radios but it also inhibits any energy being transfered
by inductance. It's like those sound cancelling ear phones. They use
a mike to pick up external sound then feed it to you with the sound waves
reversed to each other, therefore eliminating any sound. For example
when one speaker cone pulls in, the other is pushing out. Many accidentally
experience this effect when they connect Stereo speakers out of phase.
The sound level is greatly reduced because the speakers are
working against each other, but when in phase it's at normal volume and
the sound will be centered between the speakers because the speaker
cones are both moving in and out identically.

Don


----------



## roofintrash (Jan 11, 2015)

Thank you for the welcome and information BWELLS. Another ? I am going dcc,just haven't decided on brand yet. My area is 12x24 and the ? is,should I divide the layout into 2 different power districts,an upper and lower,with 2 separate boosters. It will more than likely be a one man show but you never know. Attached is a staging diagram. The main layout will be directly over this benchwork.


----------



## Bwells (Mar 30, 2014)

Roof: Sorry but I can't answer your question as I am somewhat new to DCC however I think if you start a new thread with your questions you will get more "hits" and it will keep all your questions and answers in one thread. If you need help on starting one post here. I took me awhile to figure it out. That is going to be an interesting layout and I will follow your thread. Brian


----------



## Brakeman Jake (Mar 8, 2009)

OK...let's try to clear up a couple details.Electricity isn't so complicated to handle once you get the hang of some basics.

First,the number of locomotives you intend to run at any given time will dictate how much power you need,not the size of the layout.Assuming you're in HO,a 3.5 amps. set (Digitrax Zephyr Extra) will easily drive five or more engines while a five amps. set will drive eight+.Then an eight amps. command station will propel up to a dozen+.Allow some variations with sound equipped engines but these are conservative numbers.You'd be surprised how little current modern model locos draw.

However,if you own a few older models,it's possible you won't be able to run as many as theses needed more current.

Then,the size of the layout dictates your wiring quality.Whatever the amount of energy you have available from the command station,you need wiring that's capable of carrying it all to the other end of the layout.In the present case (20 ft. or so),16 Ga. wire should be sufficient but playing safe,14 Ga. would be more than enough for the buss wires.

Wether you'll have a booster is up to you.As you said,you could divide your layout using one.However,you could also divide your layout with a Digitrax PM42...it won't give you more power like a booster would,but would allow you to divide your layout to up to four districts for much less money than a booster.

Brands...I have nothing against NCE (don't have one) but I have a Digitrax system and I'm very happy with it.Just stay away from the other sets...their only appeal is their price.


----------



## DonR (Oct 18, 2012)

Is the layout in your link only the staging area? 

You do have a reverse loop that will require a
reverse loop controller. 

I'm not sure what you have in mind with the
circle with one track connection. As it is,
once you get into the circle you must back
out.

Don


----------



## Bwells (Mar 30, 2014)

Don: I'm thinking the circle is a helix to get up to the layout and this is only the staging below. Roof mentioned 8 tracks for staging but I only see 5. Top yard, 3 with a pass thru and lower yard with 2 and 2 pass thrus. Not sure though. Brian


----------



## roofintrash (Jan 11, 2015)

Yes,that is just staging and the circle is heading up to the main level. I will be adding a couple more tracks to the ladders,just haven't got around to it yet on the plan. Dang roundtooits are kinda hard to find sometimes.
I'm in the process of readying the room for this (was my r/c workshop for the last 20yrs) and am just trying to get back into the MRR groove. The hobbies are changing Back with age.
Thanks for the help and you'll be seeing me around quite a bit.

Rick


----------

