How many ground wires to run?

Weather it’s correct or not our club has done that on our most recent modular layout. No obvious issues, of course all the transformers MUST be phased. We run everything off one AC ground. 3 mains and 2 accessory buses

I run a hot and ground wire to my track about every 6 feet. I use tubular track on a large home layout. I also solder the wires to the track, using 14 GA, stranded wire - Red and Black, separate cables.

Hope this helps: Gary 🚂

Thanks for your response. I understand the idea of dropping feeders ever so often Gary, I was asking how many ground runs I need to run.

@zhubl posted:

...of course all the transformers MUST be phased...

Not always. There are situations in very large layouts where having transformers out of phase can substantially reduce the size of the conductor needed for the common ground.

The answer to your question is that, yes, you can just run one common ground wire and connect all your feeds to it. I would also recommend using 14 gauge for this "bus" wire and 16 gauge feeders. If you happen to be using Fastrack, there are tabs under the track to which you can make your connections.

You did not indicate whether you will be using a command control system. For what it's worth, the MTH DCS command system doesn't seem to like that "common buss" wiring system, but for Lionel Legacy/TMCC the "common buss" works OK.

@Sid's Trains posted:

I am in the process of building two layouts. These layouts are the first two that I have built and have been so called permanent layouts. Something I was curious about what was the wiring. Of course I have a Hot wire for each line of track (center rail), but what about the ground. Can I just run one common ground wire underneath the layout and connect all the outside rails to it? Or, do I need to run a ground for each line?

Either way will work fine if properly laid out. On my most recent layout, which is not huge (11 x 15), I don't use a common return for anything! All circuits are two wires back to the control panel. Actually, all circuits are separate blocks, even though I don't really need blocks with Legacy it is awful handy. My longest feeder is about 15 feet.

Accessories too, all are individual two wire circuits, excepting stuff like street lamps which are daisy-chained.

What this all means is that I very rarely need to monkey around with electrical connections under the layout, because there aren't any! Now obviously on a very large layout a bus with feeders might be preferable, but for my current setup I really enjoy having all the connections accessible without crawling under the layout. Your mileage may vary.

I will be using DCS, TMCC, and Legacy. I have bought 14 or 12 gauge wire, can't remember, for my bus wires.

@ADCX Rob posted:

Not always. There are situations in very large layouts where having transformers out of phase can substantially reduce the size of the conductor needed for the common ground.

I would be interested to learn more on how that would work. 

@ADCX Rob posted:

Not always. There are situations in very large layouts where having transformers out of phase can substantially reduce the size of the conductor needed for the common ground.

@zhubl posted:

I would be interested to learn more on how that would work. 

 This method is referred as an "Edison Circuit" or shared neutral / common neutral.  If the current on both circuits, out of phase, is equal, the current carried by the shared neutral cancels out and becomes zero, reducing the wire size needed, and obviously the entire second neutral wire as well.

If you run DCS, use a discrete ground with every power feed.