Power Bus system

4230 Views 29 Replies 10 Participants Last post by SPROGman, Nov 15, 2007

breastonstation

Discussion Starter · Nov 6, 2007 (Edited by Moderator)

Hi,
I am confused regarding the Bus systems people use. I have looked at a few other threads and its confused me more.

Anyway. if I explain what I think a bus system is then could anybody enlighten me as to weather or not I am correct?.........

Basically cable running every couple of metres soldered to the edge of each rail and constantly going around the track, starting from track source? I did a search on the net for bus kits and one DCC kit I saw involved crimps and all sorts of stuff, not what I expected.

(wires in photo not soldered to track - just placed for photo reference)

The wire I am using is the same specification that comes with DCC sets. I have stripped the ends of the cable to approx 10mm and tinned them to stop them spraying out.

Any help will be greatfully appreciated.

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Dynamite26

· #2 · Nov 6, 2007 (Edited by Moderator)

A DCC bus is two thick cables running around the layout under the baseboards and they connect to your DCC controller then you have two wires soldered to every section of track which are called droppers then you connect them to the bus wire.

This what I am using for my BUS Red and Black Wires.

And I am using this wire for my Droppers which I already have in the loft and they will be soldered to every section of track.

And to connect them together I am using CRIMP BLUE TAP SPLICE & CRIMP BLADE SPLICE

Robert Stokes

· #3 · Nov 7, 2007

I'm at almost the same stage in the construction of my layout. I've already put the bus wires in. When I put in the dropper wires I'm not going to bother with crimps. I shall just cut some insulation away from the bus wire and solder on the dropper wire.

Brian

· #4 · Nov 7, 2007 (Edited by Moderator)

I have to agree with Robert. The best connection is always going to be a correctly made and soldered joint. Crimps, screw down connector blocks or just twisting wires are all likely to be sources of trouble in the future.

On a medium to largish layout I would recommend nothing smaller than a conductor size of 2.5mm and an even larger size if the layout is more than 4 plus mtrs long. I used some twin & earth (T & E) 2.5mm cable removing the outer sheathing and then laying the two insulated conductors around the layout and stripping back a short length of the insulation wherever I need to make a soldered connection to any droppers or other accessories etc. As a bonus, I also ran the 1.5mm bare former earth wire for the T & E cable around the layout as this is my common return conductor for everything that's not DCC

A couple of pictures and further explanation are on my site DCC Wiring

BTW...Dynamite26, your link to Rapid fails to specify which of the five sizes of conductor you're using as a power bus?

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3

SPROGman

· #5 · Nov 7, 2007

QUOTE (Brian @ 7 Nov 2007, 09:03) <{POST_SNAPBACK}>I have to agree with Robert. The best connection is always going to be a correctly made and soldered joint. Crimps, screw down connector blocks or just twisting wires are all likely to be sources of trouble in the future.
Also agree, and Rapid part No. 86-0390 makes stripping the insulation back very quick and easy. Although they're normally used for stripping from an end, they work just fine along the length of a wire, parting the insulation enough to solder the dropper on.

Andrew

Dynamite26

· #6 · Nov 7, 2007

Hi Brian I'm using the 1.5MM TRI-RATED CABLE rated at 21A and I am using the crimps as there isn't much room under my layout as we still store a lot of stuff in the loft so using the crimps will make it alot easier for me,if the space under my layout was empty I would solder the wires to the BUS wires but seeing as under the layout is completely full of stuff using the crimps will make the job easier.

mikeg

· #7 · Nov 7, 2007

Dynamite26, I to have many storage boxes under my layout, but have taken the trouble of moving them out to solder on the droppers to the bus wires, I tried the crimps but found they were prone to come loose when working on the layout and causing a large amount of vibration. The time to move a few boxes is much less than the time take to find out why a section of track has gone dead as the crimp looks OK but has lost contact, very difficult I found to trace, BUT I have used screw conectors between the baseboards on the bus so that it will be easy to undo if the layout ever has to be moved.

I also use a wire stripper like that described to part the insulation for the droppers and find that over a short time the gap closes up to just the width of the joint which keeps everything safe from shorts.

regards

mike g

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Brian Considine

· #8 · Nov 7, 2007

At the end of the day you cannot beat a properly soldered joint.

However, there is nothing wrong with a crimped joint provided the crimp is the correct size for the cables/wires & it is crimped correctly with the appropriate tool.

The main thing is, whatever method you use, solder, crimp, terminal to ensure that there is as much contact point between the surfaces being joined.

Makemineadouble

· #9 · Nov 7, 2007

QUOTE I'm at almost the same stage in the construction of my layout. I've already put the bus wires in. When I put in the dropper wires I'm not going to bother with crimps. I shall just cut some insulation away from the bus wire and solder on the dropper wire.

QUOTE At the end of the day you cannot beat a properly soldered joint.

I don't have a beef with the above, if your using copper wired droppers, you can simply wrap them tight around the bus, and test before soldering, or not even solder at all. The droppers won't unwind, and provided you have adequate spacing between your bus it doesn't represent a problem. On Wurzel Junction I did my original loop with soldered connections, and the expansion with unsoldered connections, intending to solder them later, but ended up not bothering because everything functioned exactly as it should. Certainly not soldering saves a lot of time. These snap type suit case connectors can fail and then you can have a hell of a job fault finding. I don't like copper tape all, and particularly not where it's placed where it will be covered by scenery. Give me a good solid copper bus sheathed or unsheathed (earth wire) and a good quality multi stranded copper wired dropper.

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Dynamite26

· #10 · Nov 7, 2007

Well you have talked me out of buying them I suppose at the end of the day a soldered joint is best so I'll spend the money on more solder as I can see I will need quite a bit of it,so I will just order the wire for the BUS and some other things I need from Rapid on Saturday.

When my mum decides she wants the Christmas Decorations down from the loft I will be able to move stuff about more better and I will be able to solder the droppers to the bus,but while I wait I can solder the droppers to the track rails in the Hidden Sidings.

dwb

· #11 · Nov 7, 2007

I solder the droppers to the underside of the rails and then use screw terminal chocolate blocks to connect back to the bus. The use of screws is a reflection of my tendency to change my mind a lot. It has already proved useful when rewiring sections for asymmetric DCC control.

The only connection problem I have is on an older part of the layout which relies on a rail joiner for continuity and the wretched thing can be intermittent. That whole area is due for redevelopment so it's not high on the remedial list at the moment.

David

breastonstation

Discussion Starter · #12 · Nov 7, 2007

right I get it now. so basically (for example single oval), 2 wires go under the track under the base board, with 2 cables connected to the rails going through the base boards to connect to the 2 cables running beneth the boards?

Please excuse my poor illustration.

2 BOLD BLACK Lines is a single track.
Red lines "Droppers"
Blue and Green lines are the bus wires for each rail.

Am I correct?? If yes, I understand with thanks for all your help people...

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dwb

· #13 · Nov 7, 2007

QUOTE Am I correct??
Yes.

David

breastonstation

Discussion Starter · #14 · Nov 7, 2007

Thank you very much !

Brian

· #15 · Nov 8, 2007

Hi Breaston
Just remember to always keep the same rail to the same colour bus wire throughout e.g. Blue bus wire always connects to the outer (or inner - your choice) rails etc. This is easily forgotten especially where a continuous loop of track is involved!

breastonstation

Discussion Starter · #16 · Nov 8, 2007

Thanks Brian, will keep that in mind.

Smokeyone

· #17 · Nov 13, 2007

QUOTE (Brian @ 8 Nov 2007, 11:14) <{POST_SNAPBACK}>Hi Breaston
Just remember to always keep the same rail to the same colour bus wire throughout e.g. Blue bus wire always connects to the outer (or inner - your choice) rails etc. This is easily forgotten especially where a continuous loop of track is involved!

Hello
I have noticed various sizes of bus wire suggested and all seem to me
much larger/far better than any supplied with a dcc system. My Fleischmann
system has wires/connectors supplied with sizing on a par with telephone cable.
How do you get round the tiny plug problem that goes in the control unit.
If you start off with say .75mm and go on to 2mm does it not rather
defeat the purpose.............

Brian Considine

· #18 · Nov 13, 2007

QUOTE (Smokeyone @ 13 Nov 2007, 07:41) <{POST_SNAPBACK}>Hello
I have noticed various sizes of bus wire suggested and all seem to me
much larger/far better than any supplied with a dcc system. My Fleischmann
system has wires/connectors supplied with sizing on a par with telephone cable.
How do you get round the tiny plug problem that goes in the control unit.
If you start off with say .75mm and go on to 2mm does it not rather
defeat the purpose.............

Always makes me chuckle that many systems have these tiny wires, that often are connected to larger ones - the trick is to keep the tiny wires as short as possible.

Brian

· #19 · Nov 13, 2007

Hi Smokeyone
As dbclass50 states keep them very short.
You didn't say which Fleischmann system your using but if its the 6803C this is only rated at 1.5 amps so the thinner wire would be ok here. The 6801 twin doesn't seem to have an output rating on their web site so its hard to comment about. But as its dual control I would expect it to be around 3 plus amps.
The idea of the larger bus wire is two fold really.
1) It allows plenty of current carrying capacity.
2) On a larger layout it helps overcome volt drop.

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Brian Considine

· #20 · Nov 13, 2007

AFAIK the Twin-Centre is rated at 3amps - I'll look it up (I've got the spec' somewhere).

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