Accessory bus wire

[Darren-373700]

2 x  0.75   ..  Would this wire be suitable for an accessory bus .. be used mainly for LED lighting and a few other bits and bobs. Can't really tell from the description, I need a piece in my hand to judge it!!

 

[What About The Bee]

2×0.75mm² should carry about 10 amps, if I read the charts properly.  That's a lot of LEDs and accessories.  

For a bus, it will be fine, if a triffle over kill.   Its okay to be too big, a problem only when undersized.

Bee

[Darren-373700]

  Maybe i could come down to the 2x 0.50 then .. and still be in spec? But use the 2x0.75 for the rails bus?

     The lay - out is roughly 25ft long and 8ft wide, single track apart from a passing loop at the station.  Was thinking of having several distribution boards along the way to sort of create hidden power sub stations for different areas, lighting houses and street lights etc.

Edited April 9 by Darren-373700

[What About The Bee]

Hi Darren

I've noticed you asking a large number of wiring questions.  That's good.  

I'm going to recommend you create a schematic of your layout.  Know all the wires and signals.  Show every connection.  Once all are known (or reasonably guessed at) then you can pick out wire to match your requirements.

Just as your idea of power districts is good, make sure all your point motors are on a separate bus.  You want to be sure that the points can operate, even if rail power is temporarily shorted.  

Now in terms of wire sizes, I'm in the US, so I think in terms of AWG.  The smaller the number, the bigger the wire in AWG. I've translated these for you to mm².   

Bus Wires
12-14 AWG 
     3.31 mm² to 2.08 mm²
     Stranded

Feeder Wires
18-22 AWG
      0.823 mm² to 0.326 mm²
      Solid wire

Others will have different recommendations, I'm sure.

Here is the theory I operate under.  Bigger wires aren't terribly more expensive than smaller wires, within reason.  You have no need for 0000 AWG¹.   But the price for 14 AWG isn't much less than the price for 12 AWG.  So install 12 AWG.  If you are feeling frisky, go for 10 AWG bus wires, its just another increment.  It does not hurt to install heavier wire, except in the up front cost.  Once installed, it will support your needs forever.  

Alternatively, you can size those wires to within an inch of their lives.  Careful engineering can save you money on the cables.  I think this errand a waste of time.  You aren't making 10,000 widgets, you are making 1 layout, a one time cash outlay.  Not a 10,000 time cash outlay.  

So slow down.  No need to rush off to buy wire.  Draw your schematic.  Understand how much of each type of wire you need.  Determine color of insulation.  You want to know what signal you are looking at by wire color, this reduces mistakes.  Once your needs are known, then you can buy the right amount of wire in the proper colors.

Hopefully this makes some sense.

Bee

¹ 200 Amp service, typically at 480 volts.

 

[96RAF]

I use mains cable (twin and earth with just the insulated wires used) for the bus wires and twin core main flex for the droppers. Cheaper by the 50m roll from Screwfix or Toolstation. 'Model Railway' wire by the metre is terrifically over-priced.

[ntpntpntp]

Being primarily a DC user rather than DCC I usually have many more separate circuits under the layout and back to the control panel, hence I use equipment wire rather than mains wire as the former is available in a whole range of colours and thus much easier to trace when fault finding. 

Main bus wiring is use 24/.02 equipment wire (for my modular layouts I run track and accessory bus right through in case they're needed by other modules either side). 
General AC and DC circuits use 16/.02 equipment wire
Low power lighting feed circuits use 7/.02 wire  

Here you can see the main loom with the bus wiring and circuits being installed under a modular system board. Still requiring final tidying up, plus those 3 brown tag boards will be wired to 37 way D-Sub sockets ready for 36 core flying leads back to the control panel. 

 It's all documented in spreadsheets in my layout "bible" 🙂 

As Bee says, plan your wiring, create a schematic or at least a connection list, and work from that.  Here's just a part of the connection list for one of my boards (the one in the photo above).   I'm detailing the track circuits, AC accessory power, points left and right, and signal aspects all going between the control panel and the board.   Of course if you decide to go fully DCC with accessory decoders for points and signals etc. as well as a track bus then the wiring between panel and board reduces significantly and you end up with a whole load more bits of electronics under the board.   I actually enjoy wiring up so I don't mind the traditional approach 🙂 

[What About The Bee]

9 hours ago, 96RAF said:

I use mains cable (twin and earth with just the insulated wires used) for the bus wires and twin core main flex for the droppers. Cheaper by the 50m roll from Screwfix or Toolstation. 'Model Railway' wire by the metre is terrifically over-priced.

Spot on!

In the US, 12 AWG is used typically in the kitchen and bathroom, wherein we can expect household appliances.  10 AWG is for clothes dryers, well water pumps and water heaters, due to the heavier current draw.  14 AWG elsewhere, like illumination circuits.

Household wire is commonly available and far cheaper than any specialty wire.  The individual conductors are color coded, to boot.  

Now there must be an equivalent to "12-4 + ground" wire in the UK.  4 color coded conductors plus the ground.  Two color coded busses in one cable.  Hoping that someone will chime in with the right UK nomenclature.  When I go to buy cable, it is all AWG, so my apologies for not knowing. 

Bee

[96RAF]

1 hour ago, What About The Bee said:

Now there must be an equivalent to "12-4 + ground" wire in the UK.  4 color coded conductors plus the ground.  Two color coded busses in one cable.  Hoping that someone will chime in with the right UK nomenclature. 

In UK we refer to 3-wire mains cable as twin and earth. The live and neutral are insulated and colour coded, the earth wire is bare, but latest standards are using a green/yellow sleeving.

Ring main (power circuits) wire is 2.5mm cross section area and fixed lighting circuits are 1.5mm cross section area. Flexible mains cable is usually referred to by the amperage it carries - e.g lighting will be 5 amp, 15 amp or larger for power appliances.

We also have triple and earth cables which are used for two-way or multi-way lighting circuits - e.g. top, middle and bottom of a stair well.