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Bus Wire size

1094 Views 37 Replies 9 Participants Last post by  PAPPA.B
Hi Planning ahead my layout will be 7mx 2.7 one side will house a 10 track +18 points storage yard the other side a station, goods yard sidings and possible small engine shed. There are some 12 base boards including one a swing gate entrance and two extensions. The boards will be wired in an upright position so breaks in between the boards rather than trying to wire underneath the layout. A couple of questions I was looking at 2.5mm for the bus is this enough, the droppers 16.02 what max length should these be. With the break at the swing gate would it be better to have two separate Bus wire sections . What would be the best way to join the bus wires at the board joints? Jim
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For bus cable 2.5mm sq. will be fine. Have a look for 6491B single cables which is good quality and easy to work with. For droppers, again 16/0.2 is ideal and try to keep them to no more than about 300mm in length. For joining bus wires at board joins Speakon connectors are probably the very best low impedance option but if you have a lot to do then these are a pretty good low cost alternative.
2.5mm may even be overkill (but no harm), it does depend on the number of trains running at any time, and their current draw, and the current limits set by any district breakers. For droppers 16/0.2 is OK, but thinner would also be fine for shorter runs - ours are thinner for quite a few inches, before joining typically 16/0.2.

Burntisland -1883 is 4mm scale, well over 12m long, sometimes 8 locos moving simultaneously. Our inter-baseboard connectors are 25-way DSUB connectors (carrying multiple DCC bus lines, and the analogue turnout and signalling controls, and some other data), and have been that way for best part of 20 years. They are made/broken every time someone sets up or dismantles a component to work on it - the layout is stored packed away, not set up. Our breakers are set to 1.5A, there are over half a dozen of them, splitting the layout into multiple zones to isolate short circuits within a zone, so typically there are unlikely ever be more than three or four locos in the same zone, with perhaps three of them moving.
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You can get white/clear plastic connector blocks that fit each other and then able to pull apart easily and refit easily, however wire is the thing and where possible (nearly everywhere) I used solid copper wire (not stranded) nor use alloy as some of this can be a bit suspect, if DCC it is only 18 volts and virtually no amps to speak off but you need good connectors. Ultimately the fewer connections you have the more reliable you are, that said my thrown together system works well as I minimise connectors only trouble is if I pull one out whilst crawling beneath the layout to fix something else.
I also use Peco joiners that have wires soldered directly to it another bother saving idea, sure after fitting you need to disguise it but that is not so difficult
Thank you both for your replies they are very helpful. I fully intend to wire every piece of rail so quite a lot of droppers to solder to the bus .
I have two boards connected with ten road storage these will have two lengths flexi track per road which works out at 40 droppers per board 20 red 20 black .
How to attach these in a tidy secure way in bunches or individually spread over the length or via a short spur no more than 100mm with droppers soldered to it?
The boards are 600mm wide so the bus wire will have travel down the middle in order for the outside rail droppers will to be no more than 300mm long.
Mounted on the two storage boards are two narrow scenic boards carrying a double track mainline which will need feeds and thus a bus wire.
Can this bus wire connect to the main bus at each end of it forming a loop?
At the entrance door there is a swing gate/bridge . If I run the bus wire completely round the whole layout I can see this as a troublesome connection so would be it better to have two separate buses for each side of the room. In which case I could return the bus via the above scenic boards and avoid a loop?
Lastly I have a NCE starter system having two buses would I need a separate booster/supply ?
Again many thanks for your help and sorry for the further questions .Jim
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It doesn't matter if the bus wires form a circle or not (otherwise a circle of track layout wouldn't work!).
For practical reasons, have the bus wires go out to where you have the gate/bridge, and then stop. One of them feeds the gate/bridge. When a train runs over the joins it completes the circle (thus proving that a bus circle doesn't matter!).

Joining lots of dropper wires to bus. Three ways, and there will be many many more:
1) screw connectors. There are things such as "earth blocks" which are like a chocolate block connector, except it has many contacts which are all joined in a solid block of metal. There are numerous variants on this, including some on printed circuit boards. Works fine. (*)
2) solder wires onto a bit of random printed circuit board, and bring the bus onto that. Works, can be fine, but can also be messy. Depends how well you solder, how its planned.
3) solder direct to bus wire. There are wire cutters which can bare the middle of a bit of wire, such as these (several makers do them) C.K Automatic Wire Stripper | Toolstation Having a bare bit of bus wire, the dropper can be soldered to it. This works, but need to keep the red and black wire joins about from each other so they won't short by mistake.

Boosters are a matter of the current draw of the layout, not anything else. You can divide the wires and send them both left and right if that's sensible. A basic PowerCab might be short of power for a layout of the size you are describing, but it depends on the locos, their power consumption, etc..

There is some sense in planning the layout bus so you can insert "district cut outs". Those provide short circuit protection for a section of layout, shutting that down, leaving the rest running. They have a number of other benefits such as limiting total current any one area may be subjected to.
How you divide things are up to you, but it may be certain lines (up main, down main), or may be certain areas (goods yard). Arrange the bus wires so you can insert cut-outs for the potential sections at a later date. The same arrangements mean you can disconnect parts of the layout to isolate and find faults, rather than being faced with "its not working, where is the fault!" problems and no way of reducing the search space.

(* if using any form of screw connector, I recommend you fit "boot lace ferules" on the end of multi-strand wire. Once you've done a few you'll wonder why you ever struggled without them previously! ).
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Hi Jim,
I use these for my dropper connections, think they are called Scotch Blocks. Quick, easy and reasonably cheap and allow for easy alterations.
Wood Electrical wiring Wire Flooring Cable

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Thanks for your replies I had previously wired part of my garage layout mostly the storage tracks . I soldered the droppers to the bus wire but I had not done much in the way of soldering or wiring in fact. So it was a bit ruff and rather untidy this time I would like to make a better job of it hence my questions. I have ordered the wire and some of the wire strippers you have suggested I will look at the various ways to attach the droppers maybe have a play before I decide which way to go. I'm not sure about the PowerCab but for now I will wait and see. I can't see me running more than three loco's at any one time as there is only me. Having power districts is that what you mean district cut outs sounds like good thing. Although I want to able to separate the boards I'm hoping that will not happen much at all once the wiring has been completed.
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Hi Alan I have used these on my Grandsons small layout and they worked fine but it has been stored for a while some years early covid . I will have to retrieve it and see if it still works the ones I have are the same but yellow. I did think about these but someone some where mentioned that they not so reliable though whether thats a particular make type I don't know I will check that out . Thanks .Jim
I suggest keeping the DCC supply to the track and the DCC supply to accessory decoders (eg points, signals) separate so that a short on the track caused by points being set the wrong way doesn't stop you changing the point to remove the root cause of the short.

Hi David. Originally I was going to use analog control for the points because I really didn't understand DCC. Thinking I would have to put an address in every time to change points but there of course a lot more to it. Still don't fully understand but it's on my must reading list I can't overload this brain to much, little and often and one thing at a time . With NCE PowerCab I'm told that this will run three loco's not sure it could run the accessories as well given there is a lot of points and probably signals ? So keeping them separate with an accessory bus is what your suggesting ?
I suggest keeping the DCC supply to the track and the DCC supply to accessory decoders (eg points, signals) separate so that a short on the track caused by points being set the wrong way doesn't stop you changing the point to remove the root cause of the short.

One thing which has occurred to me with this is that if (for whatever reason) you didn't want to use a 'proper' circuit breaker, a simple toggle switch on each leg of the 'track' and 'accessory' bus would allow for separation for fault finding.
Scotch quick connector blocks work fine if the correct sizes of wire are used in the blocks. There are many sizes of block made, to suit different sizes of wire (the main wire, and the junction wire can be the same or different sizes, depends on the block selected). Use the right wire and right connector and they work correctly. Use the wrong size wire in a connector and its all-bets-off on reliability.

Accessories from PowerCab depends on the Accessories. Some Accessory decoders take their power from the DCC bus, so they would be adding to the load. Others have their own power supply, so only really taking data (and a tiny tiny amount of current, so small it has no effect).

From the size of the layout, I would plan assuming an upgrade in power may be needed to a NCE SB5. You may find its not needed, but if its in the planning then it can be added if shown necessary.
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not sure it could run the accessories as well given there is a lot of points and probably signals ? So keeping them separate with an accessory bus is what your suggesting ?
Yes but remember that even with a separate wiring bus, you can start off attached to the same output terminals as the track bus while you see how you get on.

Some Accessory decoders take their power from the DCC bus, so they would be adding to the load. Others have their own power supply, so only really taking data (and a tiny tiny amount of current, so small it has no effect).
When you get to the stage where you think the DCC command center is not putting out enough power and you have quite a few accessories, I would consider adding a separate accessory power bus before getting a second booster.
On my loft layout my accessories (Servos at power up) which a much bigger challenge to my ECoS than my locos. A separate power supply for them was a lot cheaper than a DCC booster. Despite having a large number of locos on the track, many of them with sound, I am no where near exhausting the 4A capability of the ECoS.

As for understanding DCC control of points, consider each point a 'loco with one function'. Function Off = straight, Function On = diverge. Like a loco, a point gets a number. So to change a point, you select it on your controller and then decide if the function should be on or off.

If the controller requires you to punch a lot of buttons per point, then you probably don't want/need DCC control. It comes into its own if you a have diagram you can click with a finger or stylus, or have a control system which allows you to set up routes.

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OK thanks for the replies I have read things several times to let it sink in, in truth I have always been this way so I can't blame old age. As I said previously I am not sure about the PowerCab so my choices are go with it for now with a separate bus connection to the PowerCab Changing points individually seems long winded route setting sounds more like what I'd like. Or go with my original plan and power separately and use buttons or levers and indication lights on a panel route setting old style.
What ever I decide I need to be sure what I buy is what I need . This morning I was looking for some dropper wire I thought had. I had some boxes in the spare bedroom where all my railway stuff is stored which will be moved into the shed eventually . I didn't find the wire but I found point motors, various switches, levers and a Gaugemaster model 3 single output transformer for CDU 24v AC at 1 amp max. Also a Colbalt PSU 2 + dual 9v,2.5A regulated 18v DC at 5A. I don't know if these would be any good they sound to powerful ? Many thanks again for all the inputs. Jim
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If you are unsure about which dcc control system you will end up using then it's worth keeping your options open with how you control points. For example . . .

If you were to use Cobalt IP Digital point motors then you can either control them using dcc commands or you can wire separate manual pushbuttons to control them but with power still coming from the dcc bus. With this option you won't need separate dcc decoders, CDUs or frog juicers. It's an all in one option. Also, you can run them from your track bus because they use very little current (5mA in idle mode and just 40mA during activation). You can then simply power your frog directly from the S1 Frog terminal which leaves the S2L/S2R/S2C chageover switch terminals available for automatically powering and switching signals (or other uses). You can still power the motors from a separate accessory bus if you want to but then you need to use the S2 relay outputs for powering your frogs.

If you decide later to change your control system over to something which is more user friendly to controlling points and accesssories then all you need do is plug it in and away you go. For example, I use a Z21 control system and all my points and accessories are controlled from a 10" tablet with touch screen operation on a schematic plan. With the Z21 you never need to remember any dcc addesses for locos, points or other accessories.

Of course there are plenty of different ways to do everything. This is just another suggestion for you to consider.
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Another suggestion, would be to add the DCC Alpha Encoder, activated by switches and sends digital commands to the Bus. It runs in sequence, so you just need to connect the correct switch to the right number on the board. That will give you control from the NCE and a control switch-board.

Far cheaper than DCC-Concepts Alpha thingie, is the NCE MiniPanel. That takes either 15 change-over switches, or 30 push buttons, and will output accessory commands (and other things if you wish, such as routes, or even run little locomotive automated sequences). Its possible to attach a few MiniPanel's to a single PowerCab system, or rather more of them to a PowerPro system.
If using push buttons, then the MiniPanel works in addition to controlling turnouts on the handset. (If using change-over switches it is "instead of handset" because the handset can't move the change-over switch !).

Or, there's computer connection to NCE.
Either the NCE USB connector, to a computer, and run software of choice to control trains and turnouts, some of which will allow a phone or iPad to then set turnouts as well as driving locos.
Or there's the WiFiTrax device which provides a "WiThrottle" server within the unit (so no need for computer, and can directly use phone or iPad to control locos and turnouts).

- Nigel
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Thank you for our replies NCE Mini Panel sounds interesting and the Z21 but I think I will leave it for the moment until I am more acquainted with the PowerCab. I already have a lot of points so I will use these for now. Jim
Hi The wire I ordered has now arrived . But while I was waiting for it I thought I might have a practice on some of the wire I already had . Soldering the dropper wires to the rails seemed ok . How ever trying to solder the droppers to the bus just it would not solder. Am I not using the correct solder is my soldering iron knackered? The bus wire is some that I had for my previous layout I snipped the end off so that I had a clean piece to work with I also used my new strippers to expose the wire in the centre neither seemed to work. I am using some DCC Concepts Sapphire 179 universal I also tried some solder core wire Alloy 1mm neither that didn't work either my soldering iron is an Antex 50w it is a few years old where am I going wrong? Any help much appreciated . Jim
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