I recently isolated a new section of track which will be powered by another booster. It is my understanding that you isolate the positive (B) leads from each other across circuits, but not the common ground (O) leads. Is that correct?

Before powering this new section I tested the isolation with a meter out of an abundance of caution. The powered sections showed about 17.5 volts AC as I expected but the unpowered track still showed about 1.2 volts. Is that normal? Is some power transferred back through the ground somehow? Did I do something wrong?

I am a software guy and I admit that the EE parts of the systems I work on are sometimes hard for me to fully understand, so I am hoping that a hardware person on the forum can help me understand it this is normal or not.

Thanks!

It is all C track.

The C track is a piece of 24071 which will ultimately connect a 24711 to a 24712 - each of which will be in separate circuits. Right now it is just a single piece of 24071 connected to the turnout. That is where I placed the small red isolators from Märklin (74030) which I have always used for this purpose. The one B connector on the turnout and the B connector on the 24071 have them over the inner (male) contacts, which fit inside the female contacts on their mating pieces. I will post a picture in the next few days, since none of this is secured yet.

I have other circuits which I have isolated in this way and which seem to work fine, but I have never put a meter on the unpowered track section before. I did not isolate the ground (O) connectors, which is what I believe Märklin recommends. The isolators are old and have been used before, so maybe I will replace them with new ones and recheck it. I have always just assumed that there would be no voltage in the isolate track until it was connected to the output of a booster. This time I decided to check and I was surprised at what I found.

Jim-

I'm at a point where I'd like to add a booster. Did you set up a ring circuit for track power and ground? If so, am I correct that there would be one ground ring (brown) that both the Central Station and Booster would connect too and two seperate power circuits (red) that you can use to feed your track?

Thanks.

Thanks Jim.

Just so I'm clear, I would have one ground ring (one brown wire for the entire layout) and two separate power (red wires). One connected to CS3 and the other to the booster. So two separate red rings of wire? And I would of course isolate the track so the booster and cs3 are separate.

Sorry, just want to make sure I won't blow up my house....lol

Yes Jim is right on the money! But I actually use two ground circuits to keep everything separate and in correct order for trouble shooting if that is ever needed.


Just to help out and explain I use a separate “BUS” for each booster and yes the O (neutral/-/common) is connected to both boosters. My “BUS” on my layout is 14AWG and feeder wire size is 18AWG.

My layout has a double track mainline oval ( best way to describe it) and that is how I separated the boosters.

One booster for all the track work on the inside track of the double track mainline and one booster for the outside track. All of the track that leads off is being feed power from that booster.

See below for an explanation

..................................======
Booster. ======
===========================
===========================
Booster. ======
................................ ======

Please note the emojis are for directions of track not thumb up or down!

All the rails “O” are connected together but the “B” or pukos are separate to each booster. To get into this deeper please note that I'm using the ESU's Detectors.

I have not had any issues and my layout was built 2013.