A beginner, I am about to wire my new HO layout, but have a question about using drop feeders to a bus line. My layout is small (sectional code 80 track) but has several sidings etc. that I would like to ensure get power by placing feeders on each. I would be using feeders on the main line for every straight section and major curve. Therefore I have calculated that I could use 15 drop feeders easily. Does this sound about right for a 4x8 oval with lots of sidings? I have been doing some reading and found that some people have no problem with atlas snap switches and DCC without modification. I also want to use all the drop feeders to eliminate the need for me to solder the entire track. On the other hand, I am not sure if I am being too cautious and overdoing the feeders. Perhaps all I have been reading applies more to large, heavily used layouts.
Or is it simpler to solder the entire track? Somehow I doubt that.
Basically you trust wires to carry your current not track. Your week links are your rail joiners.
To answer your question, it depends on your track. If you are using flex, you might put down one feeder per section. In the case of sectional. You might do one every 3-4 feet and solder the joints.
I like to have solid power to every part of the track without relying on joiners.
How permanent is your layout going to be? If you intend to do lots of scenery and make it a permanent layout that will work well for years, the consensus seems to be to solder each piece of track to something - either a feeder or the next section of track. Over time, the railjoiners will lose conductivity. If you figure this layout will soon be replaced by something more sophisticated, don’t kill yourself putting in feeders - one set of feeders every 6 or 10 feet should be ok.
How many engines do you intend to run at once? If it’s only 2 or 3, the entire system current is not very high, and it’s less critical to use giant feeders on every section.
I am just finishing laying track on a layout that I hope will be somewhat permanent. I did solder to almost every piece of track (one exception was a crossing that just didn’t seem to have a good spot to solder feeders, but it does have 4 rail joiners on each polarity). At the moment, however, I am running a 2 amp DCC system on it through basically one set of feeders and relying on unsoldered joiners to pass current to the entire layout. I do intend to go back and wire up the rest of the feeders shortly.
A few feeders here and there will help, but dont go too small in gauge, I dont know what the maximum is but Im sticking with 14 AWG for both bus and feeder because of my high amp system.
There is absolutely no need for 14 gauge feeders. Just keep them short and use something much lighter. The feeders don’t carry anywhere near the full amperage of the system, only what’s going to engines in their area. Giver youself a chance with something easier to work with for the feeders. Fourteen gauge for the bus is fine.
For a steady draw of 3 amps, I would not go higher than 18 gauge. If a single set of feeders is among seven or eight that feed an entire 70’ of track cut into districts, or simply gapped, then no one district is likely (at all) to have a draw of more than about 2 amps at any one time. Even a substantial and busy yard on most layouts is inlikely to want more than about 3 amps, maybe a bit more with stationary decoders…but wouldn’t they have their own power distribution? Not sure about that.
Generally, the idea is to go lighter on the feeders, but to keep them under 18", about half of what a counter-top appliance would have. Since the bus is meant to extend for much longer distances, it is the one wire that should be robust in cross-section to keep reductions in voltage due to resistance to a minimum. Short feeders in the 18-22 gauge range will have minimal resistance for the draw they are meant to handle.
It is when there is a short in the district serviced by the feeders that the amperage can jump to the max, and that is where you will find longer and thinner feeders getting hot, possibly melting insulation and starting fires.
I used 12 gauge outdoor low voltage wire for the bus. It’s cheap and can carry a lot.
I used 22 gauge telephone wire for the feeders. I had a bunch of it and it was virtually free. Make the feeders short - 12" or less.
Since I soldered the joiners, the current path at any one point was the feeder, the track and feeder up hill, and the feeder and track downhill. Each feeder carries a small portion of the current. It’s the parallel paths created by the track, bus, and feeders that makes a stable and “stiff” track voltage. My trains pull up to 2.5 amps on +200 feet of track. My measured voltage droop is less than 0.3 volts under full-load conditions on the worst section of the track.
I’m useing 12 gauge for the buss. total of 40’. 20 gauge for the feeders soldered every 6’ with no feeder being longer than 18". And a feeder to each siding.
I solder telephone wire 12 inches long to all my track joiners before installing them on the layout. I also make them in two different colors so I know which rail is which and install them on every piece of track I use. Maybe a little overkill, but I sure have the power everywhere. So how many is to many? Only you will figure that one out over time.
My son’s 4x8 has 24 drop feeders - not counting the round house tracks, but that is WAY over kill. I would never do it like that if I was going to re-do it today. It was originally wired for block control and I just added a second drop for each original block. I think 4 would have worked just fine. One set on the main, and another set for the yard. Well, I take that back, it has a reversing loop so add another set for that.