Model Railway Forum

Hi All,

I'm looking to start wiring my layout for DCC and am confused a bit by various articles concerning the size of wires to use. One post I read says to use 24G on track droppers with 32G on the BUS lines another says 16G and 24G respectively. Also solid wire verses stranded wire.

Firstly I would have thought that the BUS wire would be thicker than dropper wires. Secondly, would solid as opposed to stranded make any real difference.

My layout is basically 'U' shaped, total length of 14m

Any advice would be appreciated.

Best Rgds,
Dave R.
Australia

MOD NOTE: Topic moved to the Forums DCC area as it may attract more views and replies.

Have you seen this
http://www.members.optusnet.com.au/nswm ... ticles.htm

or
http://www.members.optusnet.com.au/nswmn2/DCC.htm

Marcuss is a Sydney based NCE modeller

Hi Ron,

No, I haven't seen any of this. This looks like these two links will be able to answer more of my questions. Long nights ahead reading all of this.

I get so frustrated when what appears to be simple questions get really complicated and confusing answers that make one wonder if it's all worth the effort.

Thanks for the links.

Best Rgds,
Dave R.
Australia

You need to ask yourself some questions..
1) What is the total power output of my DCC system in Amperes?
2) What is the overall size of my layout?
3) Is the layout portable or permanently fixed and never to be moved?
4) Will I run a DCC bus pair around under the layout?
5) Do I want to feed every piece of track with power (and data for DCC)?
6) Do I want power zones sometimes called districts where sections of track are feed from a Booster?

So IMO the answers to...
1) Will determine the minimum wire size to be used. But always try and future proof when possible, as you never know what you may purchase in the coming years!
2) See 6 below.
3) If portable then use a flexible wire. For a fixed layout a mixture of both can be used or just use flexible wire.
4) If a DCC bus pair is run in (Highly recommended) then refer to 3) As a portable layout will need the bus pair to always be of a flexible wire. Solid wire used on a portable layout will soon result in one or more wires fracturing due to movement. If it is a fixed layout the bus pair can be solid wires, but the smaller sized droppers should ideally be a flexible wire.
What size should the Bus pair be? This will depend on the current output of the DCC system and the bus wires length. But a simple rule is... 'You can't have too larger bus wire size, but too small and it can lead to a lot of problems'! In the UK 1.5mm² solid or 2.5mm² solid is used a lot on fixed layouts and in flexible wire this would be 30/0.25mm or 50/0.2mm (15 and 13 AWG respectively).
5) Feeding every piece of track is the very optimum of performance enhancements and will ensure 100% power and data transfer into the rails. The metal rail joiners (Fishplates) then acting only to align the two rails each side. Where every piece of track is feed by droppers and so long as the droppers do not exceed 300mm (12 inches) in length rail to bus wire connection then smaller 7/0.2mm (24AWG) flexible wire can be used. If every section of track is not connected directly to the DCC Bus pair or their overall length is greater than 300mm then use a larger wire such as 16/0.2mm (20AWG) flexible wire. But remember metal rail joiners (Fishplates) are the weakest link in passing power and data rail to rail!
6) If your layout is to be large (roughly over 24ft x 10ft and these sizes are not set in stone) then consider splitting the layout up into separate power zones or districts. This is done by using a DCC Booster and its output feeds a totally isolated section of track from that feed by the main DCC console. All rails leading into and out of the Booster feed zone have to have Insulated Rail Joiners (IRJs) fitted and frequently a totally separate DCC Booster Bus pair of wires are used to feed droppers that connect to the zones rails. Note the two Bus pairs must not inter connect. The Booster bus wires size will again be dependent on the amperage output of the Booster and the overall length of the zone it feeds. But even a 10Amp Booster will work correct with 2.5mm² (13AWG) bus wires.

Please note the conversion mm² to AWG is to the nearest AWG size. These AWG wire sizes may not be readily available in insulated wire? So use the nearest AWG size sold.

The main factors are ensuring adequate power and data transfer DCC Console to rails and ensuring the DCC system or Booster trips immediately a short circuit is placed across the running rails. Any failure to trip or a delay in tripping means there is a serious problem with the DCC bus / dropper wiring!

Hi Brian,

There's certainly a lot to DCC setups than is generally known by a novice like myself. With what Ron has put me on to and your information there's certainly a lot of reading and research that I need to do before embarking on this venture. I did read that every piece of track really needs to be attached to the bus lines and I thought that it was a bit excessive, I planed to put connecting wires at each end of each base board, 1200 x 900mm and thought that was adequate.

anyway, thanks for your thoughts on the matter, greatly appreciated.

Best Rgds,
Dave R.
Australia

Hi
You don't have to put droppers onto every piece of track. But if you do, you gain optimum power and data transfer. You can have, on a smaller layout, just one feed connection and if OO use Hornby Electro point clips (2 per point) or better wire across the point on both sides like this link to item and rely on the metal rail joiners to pass power and data rail to rail. But joiners are the weak link in the connections.

Those point clips Brian spoke about are really only meant to pass power across a point to a siding or two, not to power an extensive range of tracks say as they are after all only bits of bent springy wire and not ideal for passing large currents. There have been reports on other forums about them getting hot and melting points, so use them with consideration and if using a bus system then they may not even be necessary.

Hello PomDave. I’m still at the learning stage myself and I use dcc. Lots of good advice from Brian which has helped me on many occasions along with his excellent publication. I have droppers to every piece of track including entry to points. I use insulfrog (often frowned upon) and my locos run beautifully including an 040 Peckett. Hope this helps you.