wiring for dcc
The first point to stress about wiring for DCC is that, in many respects, it is no different to wiring for DC. Connectivity is still king, live frogs still have to be isolated, a short is still a short and dirt stops everything working.
We promote the idea of 3 basic rules for DCC wiring:
1. Connect everything; the power and signal should be everywhere the track goes.
2. Do not cause a short; common sense and reversing loop modules fix most things.
3. Use conductors, wire or tape, capable of carrying the current load.
Providing you stick within these rules there are no right or wrong ways to do things; if it works it may not be best practice but it isn't wrong so you don't have to mend it.
Fishplates (rail joiners) and nickel silver rail are not the best conductors in the world so for anything but a very small train set we advocate the installation of a track bus; a 'power main' for your railway from which you use spurs to connect to the track and accessories. We have seen stripped copper wire, copper track and many types of cable used, above and below the baseboard, with equal success; just remember rule 3 above.
We are often asked at what frequency track feeds should be installed and as a general rule would advise:
- Ensure every siding or loop has at least one feed.
- Between every other set of rail joiners especially on long runs; if using short lengths of modular track let commonsense prevail.
- Do not rely on switch rail contact to feed beyond turnouts.
Although not essential, on larger layouts the use of circuit breakers to form Power Districts minimises the disruption caused by a short. Break the layout down into sensible areas, each fed by it's own track bus, so that a short in one place doesn't stop the whole railway. If you are controlling your turnouts through the DCC system the use of a seperate Accessory Bus has great merit; when a loco reaches a live frog turnout set against it the track power will be cut off but you can still change it to fix the problem.
There is a great deal of misinformation around about what must or should be done to convert turnouts for DCC use; in reality no changes are essential at all. If you can we strongly recommend the use of live frogs because pick up is better; it is not essential with DCC. You can install your turnouts the way you allways have but there are a few points worth making:
- If you are using insulated frog turnouts (includes Hornby and Bachmann points) you can connect your entire layout using Hornby 'Electro Point Clips' or similar but it is much better practise to give all sidings, loops etc their own feed.
- There is a risk with some insulfrog points that, because you are feeding beyond the point, wider loco wheels can cause short circuits at the frog. If this affects you the best solution is to isolate as if it is a live frog point. This will not work if Hornby 'Electro Point Clips' are used.
- Although you must isolate the frog you do not have to switch the feed to the frogs of live frog points seperately; you can rely on the switch blade contact. It is recommended that you do use seperate switching to feed the frogs on normal turnouts and, as with analogue operation, it is essential for crossovers and slips: A reverse loop module is the perfect way to feed the frogs on a crossover.