Very Basic DCC Bus Wiring Question (Don't Laugh!)

[latestarter]

Really sorry about this incredibly neophyte (posh for newbie) question on wiring for a DCC layout, but my experience is limited in both things electrical and model rail.

I've watched endless Youtube videos, and looked at a few diagrams on wiring bus layouts but no one seems to answer the following....

My basic understanding is  that bus wiring is basically a red and black wire of around 15 AMP gauge running under the baseboard, with dropper wires coming from various sections of the track - soldered to each side of the rails, fed through holes in the baseboard, and then soldered to the bared corresponding positive and negative (red or black) bus wires.

If I've got that about right, here's the question...how do the controller wires connect to the bus wires? No one seems to show this on YT etc, probably because it's so obvious it's not necessary. Is it simply a case of feeding the red and black wires through the side of the baseboard and soldering them to another part of each bus wire.

...see, I knew you would laugh!

Edited October 21, 2021 by latestarter

[Robert Stokes]

The wires from the controller are joined to the bus wires at any point along them, although I believe in the middle is better if they are long ones. They can be joined in any way you like, soldered or screw connectors or those ones that clip on. By the way, for bus wires I use the brown and blue ones stripped from house mains cable.

 

With the droppers be careful that you don't accidentally reverse any as this will cause a short circuit.

 

Don't hesitate to ask any question. None are too simple if you don't know the answer.

[Pete the Elaner]

Don't you think it would have been sillier not to not ask for fear of being silly?

 

I don't really know what any AWG is except that higher number means smaller.

 

The aim everywhere is to keep wiring resistance as low as possible. The bigger the wire, the lower the resistance. We need to be sensible here though: a 1m diameter copper wire is well OTT!  I have used mains cable for my bus. Don't worry about it being capable of carrying 15A. Where would the current come from? The controller booster* is the only supply & that will trip out well before 15A.

Droppers to the track will probably be a smaller gauge wire, but try to keep these relatively short to keep resistance low.

The same applies to your controller booster*. Use the biggest gauge wire you can reasonably get away with.

I use copper pins as mini binding posts, wrap the wires around them & solder. Depending on what gauge wire I use, I can fit 4-5 wires on each pin.

 

 

*Whereas DC is just a controller in 1 box, DCC is a little different so "DCC controller". Many systems are split into 3 separate components, which is a much more scaleable way to think about it. I liken a DCC system to Hifi:

 

The throttles send commands to the command station. Many systems support more than 1 throttle. a little like a HIFi supporting CD player, DVD, tuner, turntable etc.

The command station processes these & outputs low level commands. You only have 1 command station per layout. This is like a pre-amplifier.

The booster takes low level signals from the command station & provides power. You can have 1 per power district.

 

[latestarter]

Thanks for the helpful replies @Robert Stokes and @Pete the Elaner. I taught at universities for 25 years and my mantra was...the only stupid questions are the ones you don't ask. So, I should know better and the boot (for me) is firmly on the other foot.

p.s. @Pete the Elaner I've got a fairly serious hifi system (bi-wired no less!) so, your analogy made a lot of sense.

Edited October 21, 2021 by latestarter

[brossard]

The buss on my 7mm layout is speaker wire.  Don't know what the gauge is though, maybe 16?

 

Every piece of track has wire soldered to the underside so it doesn't show and dropped through the board.  I take a modular approach and like to install the wire in that way using "choc blocks" or screw terminals.  This makes troubleshooting and repair/modification easier IMO.

 

My layout is only 21' long so no issues with wire resistance.

 

Just to scare you, here is the underside of a board just after I finished wiring:

 

 

The orange wires are the buss.  Track droppers are black/green (pick a convention).  The board in the center is a Wabbit stationary decoder. 

 

There are two Tortoise motors yet to be connected (D connectors).  Other wires are for the push button actuators for the Wabbit, you can just see the green buttons. 

 

There are abundant choc blocks. 

 

I'm using chopped up household extension cords to connect to the other boards.  I want to replace these with other connectors at some point.

 

You can see my trials and tribulations in the layout link below.

 

John

[KingEdwardII]

4 hours ago, latestarter said:

and then soldered to the bared corresponding positive and negative

You certainly don't have to solder the droppers to the bus wires. There are alternative methods for connecting droppers and bus wires. My own favourite is a combination of screw terminal blocks and "Tap Splice Connectors" (Also called "Quick Splice Connector" or "ScotchLok"). These join the wires without the need to bare the bus wires and without any soldering - just a quick squeeze with a pair of pliers. The terminal blocks are used to enable the droppers to be detached from the bus wires in case the track needs to be lifted for any reason.

 

Soldering underneath baseboards is definitely a bad idea, although if you can tip the boards onto their sides, it's not so bad. I'm also wary of baring sections of the bus wires for soldering in case the bared sections of the 2 bus wires come into contact and cause a short.

 

As for bus wire sizes, it all depends on a) the size of the layout and b) the number of locos you want to run at the same time. The main factor is not so much the current, but rather the voltage drop from the controller to the point on the track where the locos are running. Bigger wires mean a lower voltage drop - longer wires increase the voltage drop.

 

In terms of bus wires made from mains flex cable (as I use) then 1.5mm2 will suffice on many layouts, although I use 2.5mm2 to allow for more locos driven under computer control. This is probably over the top, although by using mains flex, the costs are not very different. It is important that the wires are colour coded - red/black; blue/brown etc - and that you make sure to consistently connect one side of your track to one colour and the other side to the other colour. The exact colours you use don't matter, just that they are different.

 

Yours,  Mike.

[latestarter]

@brossard Stephen King books scare me a lot less than your photo! @KingEdwardII I was actually aware of the slice connectors and even have some in my Amazon 'basket', saved for later (probably much later, if I can get someone to do it for me). Thanks again for all the help, guys. Much appreciated.

[brossard]

2 minutes ago, latestarter said:

@brossard Stephen King books scare me a lot less than your photo! @KingEdwardII I was actually aware of the slice connectors and even have some in my Amazon 'basket', saved for later (probably much later, if I can get someone to do it for me). Thanks again for all the help, guys. Much appreciated.

 

That isn't the most complicated board either, didn't want you fainting clean away.

 

Mike's point about wiring underneath is excellent.  With my progressive glasses I simply can't see the work if I'm on my back.  It is really crucial to design the layout to be modular so that the boards can be mounted as you see I've done.  So much easier.

 

John

 

 

[ITG]

Have a look at Wago connectors. Various types various sizes, from such as Amazon or Screwfix. Very handy for linking multiple droppers in close proximity to the bus at a single point.

[peterfgf]

Wago connectors are great.  I was sceptical but they are easier to use than screw choc-box connectors.

Peterfgf

[Phil Himsworth]

I'll second (third?) that. Wherever I've been fiddling with electrics I've been replacing choc blocks with wago connectors; they are so much quicker and easier to connect and disconnect and don't mash the strands on multi-strand cable.

 

The only thing wago don't do are two (or more) way pass through connectors, used to connect a pair of wires to another, but there are third party equivalents that do this. (Is it a "knock off" if it's something the original brand don't do...?)

[Ron Ron Ron]

Is the OP's original question being answered  here?

The topic seems to have gone off in another direction from the first reply.

 

On 21/10/2021 at 10:21, latestarter said:

.......here's the question...how do the controller wires connect to the bus wires? .......

 

 

 

.

[latestarter]

Thanks for all the advice (again) and @Ron Ron Ron one post was specific enough but all the help I can get is welcome.

[RAF96]

If your bus wires are of a gauge that will connect directly to your controller and the ends are adjacent to you control station, then so do, else splice in a pair of suitable gauge flexi wires that do fit from the controller to the place on your bus you find most convenient. As stated this may be the middle or one end. It is usually advised to fit bus terminators on the free end(s) of any longish bus system to protect against voltage spikes that may occur from derails or dropped metal objects on track.

[KingEdwardII]

43 minutes ago, RAF96 said:

protect against voltage spikes

It isn't so much voltage spikes but rather shorts that need to be handled. Many controllers have a circuit breaker facility that will prevent damage to the controller - but if your controller does not, then you should consider adding a circuit breaker device between the controller and the bus wires.

 

If your DCC controller is being used for both locos and for accessories, then you may want to consider two separate sets of bus wires - one for the track & locos, the other for the accessories. Then it is worth considering adding a circuit breaker for the track bus wires, but seperately route the accessory bus wires to the controller so that these continue to operate if there is a short on the track. e.g. This can allow turnouts to be switched via DCC command if they cause a short due to being set the wrong way for an approaching loco.

 

Yours,  Mike.

[Crosland]

22 hours ago, KingEdwardII said:

23 hours ago, RAF96 said:

It is usually advised to fit bus terminators on the free end(s) of any longish bus system to protect against voltage spikes 

It isn't so much voltage spikes but rather shorts that need to be handled.

 

If you read (and quote) the whole sentence it is clearer. The terminators, or snubbers, are to protect against voltage spikes.

 

The voltage spikes occur due to fast changes in current combined with the wiring characteristics. This may be due to a short, in which case it happens before the system has time to detect the short and shut off the power.

[trustytrev]

Hello,

       You may find joining MERG a really helpful source of information for virtually anything you could possibly want to know about electrics for model railways.

The information available goes from basic stuff  for beginners through to state of the art stuff with help available from members too. The skills and knowledge available via  their web site and members is without doubt the best available for making informed and cost effective decisions about this part of railway modelling. 

trustytrev.

[latestarter]

5 hours ago, Coombe Vale said:

Actually, the only thing in your post which made me chuckle, (or gave me a wry smile at least), was this:-

Being pedantic, (I know I am, my wife tells me often enough!), it should have read either...

"but my experience is limited in both things, electrical or model rail."

or

"but my experience is limited in things both electrical and model rail."

Maybe you should get your wife to tell you what this forum is about. I need help on model railways. I have a master's degree and I've written three books, I'm ok with English.

[KingEdwardII]

On 21/10/2021 at 10:21, latestarter said:

...see, I knew you would laugh!

Few here will laugh at any request for help. Trust me, most of us have been there at some time or other. Model railways today encompass such a wide range of topics and to be knowledgeable about all of them is near impossible. However, you can be confident that there will be an expert out there somewhere - and quite a few of them are happy to share their wisdom on the forum here. Or in my case, explain my stumbling attempts to deal with some of the topics 

 

Yours,  Mike.

[latestarter]

9 minutes ago, Coombe Vale said:

 

Didn't mean to offend. It was meant as a tongue in cheek comment about your "don't laugh" remark. I'm sorry to have upset you. I'll always help a fellow modeller in any way I can. In this case though I don't know much about DCC. Once again, my apologies.

 

Every time I join a new forum, I hope there won't be someone who just wants to make fun of my (reasonable and often very literate) posts, and make me regret that I joined. Occasionally, I'm disappointed. I now have zero tolerance for such posts and ALWAYS report them but sometimes in vain (we'll see). 

As for your corrections on my grammar, I'm pretty sure I'm using the phrase you mentioned in an acceptable manner. But, as I said, I've only written 3 text books and worked as associate editor for a prestigious photography magazine for 12 years. What do I know?

Edited October 27, 2021 by latestarter

[RAF96]

As a self confessed grammar-nazi due to a former life as a tech author and proof reader, I get very irate with the modern idiom of using a preposition instead of a verb (e.g. I should of gone home ... instead of I should have gone home ...) or simply using the wrong verb (I brought a loco off of ebay ... instead of I bought a loco from ebay ...).

Open to correction by someone better qualified than me.

[latestarter]

15 minutes ago, RAF96 said:

Open to correction by someone better qualified than me.

 

Based on your background, there is no one better qualified than you. That sentiment is relevant to my own previous missives.

[Crosland]

16 hours ago, RAF96 said:

I get very irate with the modern idiom of using a preposition instead of a verb (e.g. I should of gone home

 

Do the people who do this actually know what prepositions and verbs are?

[SamThomas]

16 hours ago, RAF96 said:

As a self confessed grammar-nazi due to a former life as a tech author and proof reader, I get very irate with the modern idiom of using a preposition instead of a verb (e.g. I should of gone home ... instead of I should have gone home ...) or simply using the wrong verb (I brought a loco off of ebay ... instead of I bought a loco from ebay ...).

Open to correction by someone better qualified than me.

 

I think a lotta blame can be layed at the door of predictive txt.

 

If u proof reed all the posts in RMW & other antisocial media that you inhabit u wood need 2 bulk by red pens.

 

or

 

I think a lot of the blame can be laid at the door of predictive text.

 

If you proof read all the posts in RMW & other (anti)social media that you inhabit you would need to bulk buy red pens.