BUS wire connection

[Exec]

For a DCC layout, what is the best way to connect the BUS wires to the track

[96RAF]

My longish reply fell foul of the profanity filter for the commonly used ‘,,,,,,,’ word meaning threaded connection method. It was immediately deleted before being offered the chance to amend the ‘error’. The Bug has been reported.

I will reply more fully when the filter is amended.

In the meantime solder is the best way of connecting droppers to the rails, and for connecting dropper wires to the main bus wires. Pre-wired fishplates are convenient but not recommended by me as they are exactly the worst place to put dropper wires for reliability.

Various mechanical methods can be used to connect the droppers to the bus.

[morairamike]

Hi.

On each piece of track, no matter how short, solder one wire on the underside of each of the tracks. I use black on the left and red on the right. The wire is 7/0.2 it passes thru the base board and is soldered to buss wires. These are 1.5mm mains flat twin and earth. They are removed from the outer casing but still in their own insulation. They start from mid point of my layout and radiate to the left and right. They terminate at the access flap. A snubber is fitted to each at the ends. The wires are twist once every 0.5 metres. The insulation is removed where the droppers wires attach. The dropper wires are wrapped around the buss wires before being soldered. No matter how many tracks I have in a section all are fed from the one pair of buss wires. The maximum I have is 5 tracks in a section. Max number of locos I have run at one time is 7. No problems encountered. But number is limited by brains ability to control number of locos. Picture is the underside of the access flap showing wires, flexible inter connect to next board and the snubber.

[Flashbang]

Hi

A DCC Bus pair needs to be able to return a fault current within a millisecond to the base or booster unit. Normally 32/0.2mm or 1.5mm2 solid wire is about the minimum to be used. They of course also need to be able to supply full current to the rails as provided by the base/booster unit. Only use Solid wire on permanent layouts and on any portable layout always use flexible wire.

Droppers (Bus to rail) wire size then 16/0.2mm is the recommended dropper wire size, but 7/0.2mm can also be used, but only if every section of track has a dropper and the droppers overall length is kept to a maximum of around 500mm.

Always try and use the same colour insulation for both bus wires and droppers, as then there is far less chance of a cross connection.

All outside rails need to have the same coloured dropper connecting rails to bus wire and the other chosen colour dropper and bus wire connections for all the inner rails.

The very best connection is a twisted and soldered one. But there are other methods including Screw Terminal blocks, Scotchlock connectors of the correct size for the wires. Warning... using the wrong size Scotchlock connector can result in a High Resistance connection or worse a broken (Cut through) wire. Even Wago style 221 blocks are useful.

[AceinOz]

What is a ‘snubber’ (as per the photo above)? Also, does the bus wire come straight out of the A/B connection at the back of the select?

[96RAF]

Yes the power bus wires connect to the controller A-B track terminals.

A snubber is a pair of electronic components (resistor and capacitor) tuned to damp out spikes in the power bus. These spikes can be caused by many things and may damage your loco decoders or other electronic kit wired to the track.

They are simple to make. Component values as shown.

[Rog RJ]

A snubber is used to eliminate voltage spikes which may occur under certain fault conditions, such as a momentary short circuit which can sometimes happen as locos and other rolling stock pass over a point or if there is derailment. It consists of a capacitor and resistor, normally connected to the furthest endpoints of the track.

Yes, bus wire connects to the output of the controller, possibly via other, flexible, wires if the bus wire is too stiff.

Edit. Rob posted while i was typing.