LION recommends a HARD GROUND.
LION has several different power supplies. A floating common has its problems since stray voltages will make their home there and make trouble shooting almost impossible.
Thus the common is a HARD GROUND, all stray voltages will go away.
OK, LION has not DCC, obviously the DCC is not participating in a common return, but the system should be plugged into the wall with a three prong plug and trust the manufacturer to do whatever it is he needs to do inside of the box.
LION has a 10.2 volt regulated power supply putting out 12 amps to the tracks.
The LION attached the negative post to GROUND, and the Positive to the railroad. On the Railroad, the LEFT rail is grounded and power is applied to the right rail. Obviously for YOUR application you will need to do things differently, but since subway trains do NOT run backwards, it is not necessary to worry about reverse operations. LION has plans for that eventuality.
The Tortoise power system consists of two DC supplies, the + of 1 is connected to the - of 2, and this is GROUNDED. This leaves the LION with +12; -12 and 24v dc outputs. Tortoise machines are connected to GROUND and to the "Stinger" that is the circuit that drives the turnout, - = normal; + = reverse.
The SIGNAL / Track Detection system has a 16v dc transformer, neg=ground, pos to the system.
The AUX system is 12v dc, neg=ground; pos lighing circuits.
With all of this you can see why the common must be GROUNDED.
OK, YOUR railroad is not this complicated, but good practice suggests that your common must be Grounded.
ROAR
