wiring

[aleopardstail]

Think I have this right, least I hope so as this is whats on order.

32/02 wire for the DCC bus (12'x7' layout, will be a 5A capable system eventually though), the same for the 15V feed to the DCC unit
24/02 wire for the DC bus, 5V and 12V (controls and lighting mostly), note the DC ground to the DCC unit will be 32/02
16/02 wire for track droppers & frog wires, basically anything feeding a single length of track.
then I have individual feeds to various control modules etc as single core hookup depending on current requirements.

its probably overkill, but better than underkill for reliability

[Flashbang]

Hi
I have commented next to your post in blue - it was easier!

Think I have this right, least I hope so as this is whats on order.

32/02 wire for the DCC bus (12'x7' layout, will be a 5A capable system eventually though), the same for the 15V feed to the DCC unit Good choice, but Bus wire can go larger. 32/0.2mm is good for 6.0Amps
24/02 wire for the DC bus, 5V and 12V (controls and lighting mostly), note the DC ground to the DCC unit will be 32/02 You should not connect DCC to DC keep them totally separate. But I guess you're talking about a separate power source that feeds the DCC command console? Do not use the same insulation wire colour for each function. Using different insulation colours really helps with wiring and later fault finding!
16/02 wire for track droppers & frog wires, basically anything feeding a single length of track. IMO 16/0,2 is a bit on the large side. 7/.0.2mm would be ample for frog wires and dropper wires if kept to a maximum of around 300mm rail to bus wire. Again use the same two insulation colours for droppers as the DCC bus pair.
then I have individual feeds to various control modules etc as single core hookup depending on current requirements.

its probably overkill, but better than underkill for reliability Highly agree

[aleopardstail]

idea is there is a power board, this has 15v (which gets white), 12V (orange) and 5v (red) with a common ground (black) - that is the larger cable to the DCC base station (15v & ground). then there is a 5v and 12v bus with 24/02 ground around for stuff like lighting point servos etc

the DCC bus is blue & brown in 32/02 out of the base and then 16/02 for all droppers to that bus, aware this could be slightly large in some cases but to be honest its not physically too large and easier to have all feeds the same size. also avoids splitting shorter/longer blocks

totally agree the DC/DCC kept apart in terms of wire colours, have a scheme I've used for a while, the above are power. yellow is "signal" wire from sensors, often single core hookup, sometimes 3.3v. indeed may pick another colour to have 5v signal and 3.3v signal individual

[Flashbang]

What DCC system is to be used?

[aleopardstail]

What DCC system is to be used?

will be DCC-EX, initially a 1.5A shield, but later the 5A system they are promoting. supply is rated for more slightly as that was the AC-DC converter I could get easily. have used this system before, the 1.5A is fine to shift a pair of locos to test, swapping later as doubt more than four will ever move at once

[Suzie]

Think I have this right, least I hope so as this is whats on order.

32/02 wire for the DCC bus (12'x7' layout, will be a 5A capable system eventually though), the same for the 15V feed to the DCC unit
24/02 wire for the DC bus, 5V and 12V (controls and lighting mostly), note the DC ground to the DCC unit will be 32/02
16/02 wire for track droppers & frog wires, basically anything feeding a single length of track.
then I have individual feeds to various control modules etc as single core hookup depending on current requirements.

its probably overkill, but better than underkill for reliability

That is spot on. Exactly how I would do it.