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Discussion Starter · #1 ·
hello all,
I am about to start with dcc for the 1st time.Every thing i have read says to use larger gauge wire than for dc,especially the bus.
Can anyone tell me which gauge to use?
I have been to Alan Gartners site but he gives all sizes in Awg(well he would he is American). the only site i have found in the UK gives a size of 32/02 but this is presumeably pre-decimal as all cable now seems to be in mm.
thanks for any help any-one can offer.
MickD.
 

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MickD

Hope this helps, i have been using 1mm cable for my track supply with no problems what so ever, 1mm cable is capable of carrying 5amps without over heating or even getting warm.
 

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I spent some time trawling through online Lenz manuals where I eventually found a recommendation to use 18AWG. Like you I then had to translate this into something a bit more understandable. During a visit to the RS website I found that they do UL Listed cable in AWG sizes, so I bought a 305M reel of black 18AWG. It's quite chunky stuff but I have now completed wiring a bus around the layout. It works fine with my existing H&M Duette but I haven't actually bought any DCC kit yet.. I'm still saving up for that.
 

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What I use - and it may be overkill, but I'm happy with it and it works well - is the same wire that you use to wire up a household oven for the DCC BUS.

For an oven they say that for lengths up to 12 metres, 4mm² cable can be used otherwise 6mm² cable should be used for lengths up to 20 metres. The same could be said for DCC.

This big wire is nothing really to do with amps. The DCC system is only about 5 amps, but it is more to do with good signal quality.

I then use 1.5mm² droppers (the same wire for household lighting circuits) every metre or so, to link to the track.

I do this basically because I had a bunch of it left over from some renovating.
 

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>Droppers
I've found that with the 18AWG I can solder it "end on" ie at 90 degrees to the underside of a Peco fishplate. It seems sturdy enough if the joint is made properly - not one of my strong points.
 

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Discussion Starter · #6 ·
Thanks for the replies.As an afterthought do i need stranded or single strand wire?and is nit safe to solder this thick wire to the rail without melting sleepers &chairs.
thanks for any help much appreciated.
MickD
 

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MickD,
As you can see people use quite a lot of different sized wire for thier main bus. I don't know the exact thickness of mine, but it is about the same thickness as the three wire (Brown, Blue, earth) stuff you find in the cable of most house-hold appliances.

One suggestion. make sure you buy two colours, and from then on, colour code all your power bus activities. Might I suggest Red and Black. As for droppers/ feeders I use the thickness you buy for wiring Peco/Hornby points. The Signel Box in Rochester does nice large rolls. Again If you are colour coding buy plenty of red and Black and a bit less of the green!

So here you have the answer to your last question. Solder the thin stuff to your track, easier to master, and then its a very easy solder to the thicker bus wire.(Some people, I hear, dont even bother soldering the droper wire to the bus wires, they just twist it on).

Just one method among many

TVBG
 

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Re Bus Cable size: I've used 32/0.2 (mm) wire from All Components - this is rated at about 10 amps - I was setting up a bus for a Hornby Live steamer which takes 6 to 7 amps. But I have run the two wires as complete loops round the layout (which is an oval-shaped continuous run) to minimise voltage drop, rather like a household 'ring main'.

I used 1 sq mm single strand wire as the droppers - ex mains lighting cable - soldered to the outside of the rail. Bend over the end for 3mm at right-angles, then solder to the side or possibly underside of the track. Connections are made between the droppers and the bus cables using 10A PVC terminal blocks. Pairs of these are slide onto the two droppers and the bus cables put in at the other end and all screwed up tightly. Seems to work OK. Reduces heavy-duty soldering and is easy to undo if the track has to be moved for any reason.

Heavy-duty (ie fires, washing machines and like appliances) use 1.25 sq mm flexible cable, but buying and stripping this down is rather more expensive than buying 10m lengths of individual cables.

Good running,
John Webb
 

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My own experience of bus wires on a large layout (by UK standards) was to use bare copper earth wire. This being approx 7mm Dia. and being the cheapest and most available in South Africa. The bus wires were seperated for obvious reasons at 70mm apart. The bus wires were tensioned before fixing. On one layout we used shackles to increase tension. Multi stranded copper droppers were used, and these were simply stripped and wapped around the bus without any soldering. You will note that the droppers do not become loose and suffucent contact is made for full conductivity so why bother to solder ?. None of the three DCC layouts wired in this manner had any problems, I feel this is a simple method of laying a bus and it's highly effective. For those of you who don't like bare wire, there's no difference between this and copper tape.
--------------------------------------------------------------------------------------------------
For those of you who dont like my method the text below is from Richard johnson of DCC Concepts. i've had quite a lot of correspondence with him in the past. This was posted on DCCUK sometime ago:

First, define: "long" as any bus longer than 30 feet - below this the
twisting benefit is minimal. The twisting has NO effect on Radio
interference at all - it is to prevent power drop and improve the quality of
the DCC signal.

You can keep power bus lengths short by placing the booster in the middle.
Do NOT make a full loop of the bus.

(1) The benefit comes from twisting the main part of the bus. You should
NOT twist the droppers between the bus and the rails, as apart from making
it very difficult from no benefit it will possibly make any "inductive"
detectors less effective if you choose to use them.
The benefit of twisting the bus is to prevent an increase in the impedance
of the wiring by cancelling any inductance created by the square wave AC of
the power bus signal.
The terminator at the ned of the bus is an effective easy to keep the signal
clean and should be made from a 120 to 150 ohm resistor (3w) and a 0.1Mfd
Ceramic capacitor in series with each other - these two components simply
added across the end of the bus.

(2) All long DCC bus wires benefit from being twisted - and if the
control bus is long this is best done with computer network cable, as this
is twisted inside the sleeve for the same reasons.

(3) No need to keep an accessory power bus and a main track power bus
apart. They carry the same sort of signal and don't interfere with each
other.

(4) DO definitely keep the track power bus and the control bus apart.
Its best to cross them at right angles. I'd define more than 150mm as an OK
separation, but farther away is better.

(5) No need to twist ANY other wiring other than to keep it tidy. Never
a need to twist DC wiring - it does not have the same problems as the DCC
square wave signals on the power bus.

Kind regards

Richard Johnson
DCCconcepts
 

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Hi all,
Some good, some confusing and perhaps some silly information appearing here!
While I'm a complete newcomer to DCC, I do understand electrical / eletronic theory and have been around model railways for far to long a time to state here!

I have read above about 4mm2 or 6mm2 cable being used. While this will work it's a huge cable size - 6mm is approx ¼ inch dia. and quite hard to flex.
Remember, all were trying to do is improve the electrical (data) path rather than rely on the rails and the rail joiners (Fishplates) to every part of the layout.

I cannot see anything wrong with using either 1.5mm2 or 2.5mm2 wire as the main bus.. Easiest of all is to buy some cable - Two core and Earth (T & E) and strip completely off the outer sheath and discard the bare earth wire. The two insulated cores Red & Black (or Brown & Blue depending if the new 'Harmonised' cable is used) remaining are then fed all around the layout. Leave the insulation on as this helps identify which conductor is which when connecting local feed wires from the bus to the rails.
At each location where a feed is required to rails/static modules etc simply strip back the cables insulation with the aid of a craft knife for approx 25mm and solder the flexible dropper wire or feed wire onto the bus. If you don't like soldering, then simply cut the bus cables at the location needed and insert a choc block connector strip (screw terminal block) in line and take the local wires out of one side of the connector strip then continue on to the next location and repeat etc.

Twisting cores isn't in my opinion really necessary for most layouts (unless your layout is over 30 feet in any one length!). While twisting cable cores can, and does in long runs of wire, help reduce cross talk, if we were to use the rails as the bus we wouldn't be twisting these! The main thing to do is try and keep the bus cables away from anything that could induce interference into them i.e. don't run them to close to any mains electric cable or sockets or near any mains operated electric motors - washing machines, Tumble driers etc. (Perhaps these two examples are unlikely but worth a mention!)
 

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Brian,

I agree with all of that.

Very good point about why we in fact have the bus in the first place. e.g. so we do not rely on fish plates. Also the power bus makes life much easier if we use electro frog points, (some)stationary decoders and the fancy stopping signal units later, as we progress from the basic train set.

TVBG
 

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Been reading this thread since yesterday and i have decided to wire my layout ready for the change to DCC towards the end of the year,so i was wondering can i use 2-Core 6A Mains Cable for the track power found hereTrack power wire and would that be ok as electrics isn't my strongest area as i only found out how to wire my seep point motors up for point indication last week.

As doing it now while track laying will save me time when i change over towards the end of this year,as if i can use that wire i can get some this weekend as i will be laying track on the lower level this weekend.
 

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I could use 1.5 or 2.5mm T & E cable for the bus wire and use 2-Core 6A Mains Cable from the rails to the T & E wire bus wire.

Soldering isn't a problem as i am pretty good also i will be soldering the wire to the underside of peco rail joiners as it's easier for me to do than trying to solder to the rails, and the wire will go into a wire block then to the bus wire.
I find the wire quite easy to strip as i got some 2 core 3A for my point motor wiring.
 

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Hi Dynamite26
Nothing wrong with what you're suggesting!

Consider perhaps using the bare earth wire removed from the 1.5mm T & E cable as "droppers" then solder your flex wire onto these and then onto to the main BUS cable wire?

Have a look at what I mean on my site about a 1/3 of the way down the page http://www.brian-lambert.co.uk/Electrical.htm
 

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Discussion Starter · #17 ·
Thanks to everyone who sent suggestions.
there doesnt seem to be a definitive answer?.
I seems as if anything above 2mm rated at 6amps or more is as good as anything?.
Good idea with the chockblocks & soldering to the rail joiner!
Again thanks for the feedback.
MickD
 

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When i soldered wires to railjoiner on my old layout i soldered them off the track then fitted them to the track as it was easier doing it that way as i didn't want to melt the sleepers trying solder the wires while on the track.
 

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All
A word of caution on soldering droppers (feeds) to rail joiners (Fishplates).

It is this very fishplate that cause us so much concern, strange problems and head scratching due to the poor connection they make onto each section of rail fitting into them! What often happens is the fishplate and / or the rail end isn't 100% clean when the initial track is laid and a high resistance (HR) joint ensues. This joint may work ok for a few months or even a year or so, then slowly it will become worse until finally you lose power to a section of track or the locos on that section suddenly slows for no apparent reason.

I believe it's much better to solder the dropper or feed wire directly onto the rail itself. Either, as I do, and solder it onto the rails outer side or if you prefer underneath. The underneath method can only really be carried out when the track is being laid, as a hole for the wire or dropper to pass through is needed directly under the rail and also its very difficult to solder onto the underside of already laid track! What ever method of electrical connection chosen, don't solder the fishplate to the rail ends or eventually you will see your track buckle in the warmer days of summer!
 

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I must agree on the inadvisability of trying to solder to fishplates and the reason why not. Apart from not helping at all with electrical contact, it's easier to make a decent solder joint to the rail anyway.

It would be interesting to try to estimate a 'safe' maximum length of continuous track that would not be affected unduly by expansion/contraction. Once this was established, then perhaps it would be beneficial to solder rail joints up to that maximum length and just bridge the odd remaining fishplate joint with an inconspicuous wire loop. That seems like a problem free compromise.
 
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