The power bus is not overkill. For rule of thumb attach a feeder between the bus and each piece of track, dont depend on the track connector to carry the current between each piece of track. This also allows you to leave the track connectors unsoldered and allow for expansion / contraction movement.
Having said that, not everyone agrees and some have other schools of thought.
You won't go wrong with using 14 ga. for the bus and 20 ga. or so for the feeders, and keep the feeders short (12" or so). Make the bus insufficient and you will only have grief.
selector The idea is, if the quarter does not result in the system detecting the short, it has too much signal-to-noise, or rather noise-to-signal, and can't see the problem. This is almost always caused by poor voltage where the fault is. The convention is to simply alter, or improve, the voltage there, and that is often as simple as providing another pair of feeder wires.
The idea is, if the quarter does not result in the system detecting the short, it has too much signal-to-noise, or rather noise-to-signal, and can't see the problem. This is almost always caused by poor voltage where the fault is. The convention is to simply alter, or improve, the voltage there, and that is often as simple as providing another pair of feeder wires.
No. Signal to noise has nothing to do with it. As the signal is pure digital, it is either +14 or zero volts, (H0) so it cannot get lost in the noise.
Circuit protection works on rate of change. Too much impedance, and the time constant created by the inductance and resistance will interfere by impeding that change. So the booster will not see a sudden rush of current and shut down.
It doesn't care about the amount of current, it cares about a sudden change. Which sure beats a 3A current flowing through a short melting something because it needed to see 5A to trip.
This is why the 'quarter test' is a good gauge of the robustness of the power distribution for a DCC-operated layout. Placing a quarter or screw driver blade across both rails shorts the path of the electricity and should cause the system to detect the fault and to cut power to the rails in order to prevent damage to expensive things...................like decoders.
But, all of this is near moot if the power has so long to go, or if the resistance is high further upstream. A larger wire bus helps to keep the 'pressure' of voltage high further down the rail system, and from there you can simply add feeders up to the rails with minimal voltage loss. This logic works until even the bus can't cope with the distance due to internal resistance, and at that point one must consider what is called a 'booster'. From there, if the rail system is so vast, you would run yet another bus, and from that bus more feeders.
Not bus bars, but the power bus.
Yes, there are good reasons. See https://dccwiki.com/Power_Bus for more information.
As nickel silver has a lot more resistance than copper, the purpose is to reduce the impedance in the circuit as much as possible, to minimize voltage losses over distance. Inadequate wiring causes problems, notably it can interfere with the short circuit protection.
For example, C100 rail can have 10 times the impedance of an equal length of 14AWG copper wire.
https://dccwiki.com/Rail_Size has impedance values for various rail profiles.
There is nothing about bus bars in your question.
One rule of thumb is a piece of wire or a soldered connection to every piece of rail. Because of expansion and contraction of the bench work, soldering every joiner is a bad idea. The other rule of thumb is a feeder every 6 feet. I would also suggest not soldering turnouts. It makes them easier to salvage if you start over.
When you ask about numbers of trains, lighted cars, multiple engine consisits and sound, you are really asking about how many amps do I need to run trains and how many boosters, not the quality/quantity of wiring. The introductory books seem to think that boosters are practically free and you should use as many as possible.
Eventually you are going to get sucked into the "power frogs or not" question.
A good site is http://wiringfordcc.com/ He gets too wound up about using auto bulbs for circuit protection. They do not provide adequate protection to prevent a decoder from burning up, so skip over that part.
Henry
COB Potomac & Northern
Shenandoah Valley
There are good reasons, mainly to keep from having voltage drops across a layout, especially as layouts get bigger.
If you have a 4x8, the sure, a bus is probably overkill. Just like anything, it depends on size and scope of a layout.
Here is the big picture. DCC powers all the track all the time. As layouts get bigger, to provide sufficient power for all engines that may need to run and to make trouble shooting easier if there is a short, you divide the layout into power districts and have more than one DCC power booster. All track still gets a signal but boosters make sure that there is enough amperage to power all engines on a layout.
A single power booster may typically be 5 amps for systems like Digitrax or NCE. Depending on how much load an engine puts on the system, you can only run so many engines before overloading that 5 amp booster. So by breaking the layout into power districts, any district would hopefully have sufficient power for what ever engines are in it. Obvously it takes some planning on that front.
As for the bus, each district would have it's own bus and you provide feeders to the rail frequently from the bus. That ensures no dead zones and even power to the track. Otherwise you would be relying on the rail joiners to reliabley feed power to the rails from track section to track section.
I am not sure if there is a rule of thumb, but I would think for flex track, having a feeder to every other joint would be a good minimum. Every other joint would mean every piece of flex will have it's own feeder going to it.
Rather than solder rail joiners, I leave them unsoldered to allow the rail to breath, or expand and contract. I solder the feeder to the rail joiner instead.
Rio Grande. The Action Road - Focus 1977-1983
Is there some sort of rule of thumb for how many times to attach power to the tracks? Length, number of trains, lights on caboose, etc.? These bus lines seem overkill, but I assume there are good reasons.