DC bus wire.

[OOLee]

Afternoon all,

Hopefully after Xmas I'll be extending the layout to run around the perimeter of the attic room ( at present the main layout board is at one end of the room) I know a lot of folks say that there is no need to run a bus wire with droppers for DC but as the layout is in the loft and although it's insulated and boarded ( used to be a bedroom ) the temperature still fluctuates during the different seasons so for this reason I don't really want to be soldering the fishplates.
I was thinking of running the bus wire around the extended loop and adding droppers to ensure a good power coverage, I know this is most probably overkill but as the loop will only be around an extra 40ft the cable is fairly inexpensive and I don't mind doing a couple of hours work if it benefits the layout.
I've attached a picture of the cable and the specifications that I was thinking of using and would appreciate any information if this is suitable and or any other information or tips that may be useful to me doing this

Cheers, Lee.

[Steve M]

Many use wire stripped from domestic twin and earth cable - compare prices as this may be a cheaper option.
Bit worried that you were considering soldering the fishplates - that's not recommended in any environment. A bus wire, even for DC, is always the best option.

[Brian]

Hi Lee.
DC unlike DCC (Digital) provides far less current to track. Typically an average DC train controller such as a Gaugemaster can output around 1.0 to 1.25 Amps maximum before the overload trip cuts off power.
Even with volt drop your wire from a standard DC train controller need not be larger than 16/0.2mm, which is equal to 0.5mm² or around 20AWG. If you intend to use Common return wiring, where all the controllers are each feed from totally separate power source and have one single (common) return wire, then consider increasing that return wire size to 32/0.2mm or 1.0mm² or 17AWG.

The use of 2.5mm² or similar 50/0.2mm or anything larger is just over kill and is not needed for a DC layout.

Never solder rail joiners (Fishplates). Just use them to align the two abutting rails and where air temperature is likely to swing widely (as in a loft or garage etc) then lay the track when the air temp. is around 20C and the track has been at room temperature for a day or so. I always allow a small gap in abutting rails. The thickness of a business card is about right. The rails can then slide inside the metal joiner depending on ambient temperature. Droppers on each rail section will always provide the very best power to the rails.

[OOLee]

Thank you for the input gentlemen, as I've usually had temporary layouts I've never soldered or permanently fixed track but I've read about people soldering track together and having problems with it lifting in heat etc that's why I really didn't want to do it that way preferring to use a bus wire as I mentioned in my first post

Cheers, Lee.

[Tricky Dicky]

One issue you will have with a bus is with switched sections as it will not be as simple as to provide a break in the rail and simply wire a switch across. It is not impossible the switch will have to be wired into the dropper of the relevant section but if you are having a central control panel you may not actually save much in wiring. Having said that a bus wire will ensure you do not have to rely on the fish plates for current continuity and if you decide to go DCC at some point in the future you at least will have the ideal setup already.

Richard

[OOLee]

Thanks for the advice Richard, still plenty for me to learn that was my thinking with adding the bus wire so that the track would have better connectivity plus it's nice and peaceful up the loft so I don't mind a little bit of extra work doing the wiring

Cheers, Lee.

Ps. my brother in law is an electrician so I'll get him to run is eyes over everything just in case

[OOLee]

Just wondering if the cable pictured would be a more suitable size for dc bus wire

Cheers, Lee.

[Brian]

IMO its too large a conductor size, but it would work OK.
I guess its really the cost of the twin wire v cost of a few metres of 16/0.2mm equipment wire.

[OOLee]

Thank you for the reply Brian, I can get 50m of the above cable for about £16 so if it will do the job I think I'll use it for the main bus wires and use smaller wire for the droppers

Cheers, Lee.

[bulleidboy]

Hi Lee - I expect you already have a pair, but a decent pair of wire strippers is essential when adding droppers to your bus wires. They will allow you to pull the outer covering of the bus wire apart, so that the dropper from the track can be soldered/connected to the bus wires. Ideally use the same colour wires for your bus and droppers. I used blue and brown, and as the layout is "U" shaped, the nearest rail to me when standing in the U got one colour, and obviously the outer rail got the other colour.
This picture below is purely to show the style you need - they are available from various sources.
https://www.toolstation.com/minotaur-au ... n0QAvD_BwE