More info

jtw,

There is a wealth of knowledge out here among the forum members, but accurate answers require more information.

How many operators?  You alone, or more.  How many trains will be running at once.

How big is the layout?  Is it a simple switching module?"  Around the wall switching?  Lots of mainline?  How many feet of mainline.  Single track mains? Double track?

Sound-equipped locos?  Passenger trains with lighted cars?

What accessories?  Powered switches?  Lighted buildings?  Signals?

DC may be OK.  My guess is that sooner or later, as your layout develops and as you operate the layout, you will find that what you want to accomplish can be best handled with DCC.  (That's what happened to me:  I built (or partially built) 6 layouts with DC, but after looking into what DCC allows me to do, I jumped in, am not looking back.)  With DCC, you're controlling the locomotive, instead of DC, where you're controlling the track and whatever happens to be on it.

Tell us what you have decided on, or what your plans are, and we can narrow down the options, and of course suggest some budget-conscious choices.

Default Answer

In the absence of specifics use 12 ga. for track power, 14 ga. for accessories buss. Enough to power any size layout and unlimited accessories.

Budget

In cost  and time alone, wiring the DC layout is more expensive than wiring the DCC layout.  In DC each block needs its own feeder and control switch.  A control panel and associated wiring is also needed. 

That being said, the DC layout does not need to be rewired to run DCC--just connect the DCC system to one cab and turn on all of the blocks so one can switch to DCC in the future.

To amplify a little on Alan's statement,  The wire sizes he suggests minimize the voltage drops caused by the wire resistance, when running a lot of locomotives on a larger layout--they also work on smaller layouts.  For appearance, use smaller wire (I use awg 20, others use other sizes) to connect to the actual rail.  Keep this short as less than 6 inches.

More detail on the layout is definitely needed, including size, operation plans, era, etc.

There is no one way to wire a layout "correctly."  Just a group of items that need to be considered and handled properly.  Pick the ones that fit your skill set and budget.

Terry

Here more info.

My layout is going to be on a 4 x 8 sheet of plywood with a 2 x 3 extension for a switching yard.  I plan on run maybe 2 locos at once. I will have a town with lighted building and street light and signal lights.

There will be some switches and other accessories no quite sure of it all yet.  I do have some passenger cars that are lighted cars.

I would like this to be expandable in the future.

Thanks again for all the information.

One advantage with dcc that you may not have considered.

If you stick with dc, you will be forced to run locomotives at what ever speed they do from the factory.  If you are never going to run multiple unit lash ups, that is not a problem, but with dcc you can speed match locomotives so that you can mu any combination of locos and get them to run together.

Right now sound is probably not an issue.  I don't know of any sound system that is small enough to mount inside any N-scale locomotive.  They may eventually miniaturize the decoders enough to fit, but how long before a speaker is made small enough to fit?  Right now the "state of the art" for N-scale sound is multiple external speakers mounted around the layout with electronics that allow the sound to go from speaker to speaker "following" the train around the layout.

Russ, I must be missing

Russ, I must be missing something here. There are N scale decoders with sound that drop into N scale locos. The quality of the sound may be suspect but they are out there. 

john

N scale sound

Here is an example of using a Tsunami TSU-750 in a Kato E8 N scale loco that I did a couple years ago...

https://forum.mrhmag.com/post/adding-sound-to-an-n-scale-loco-12186489

Loksound also has a small sound decoder I plan to try out in another loco at some point.

Thanks for the info on sound.

I model in ho, and this is the first I've heard of sound installed in locos in N-scale.  How does it fit in more modern units with narrow hoods?  It would be relatively easy to put sound in an E-9 or F-7, but how about an Sd40 or Gp50?

Tight, to be sure

Don't want to hijack the thread, but I'm working on an install in an SD40-2.  I'm going easy by removing the motor to fit everything in (which it then fits easily), but I do want to see if I can do an install and keep the motor.  

My 2 Cents

I am on my fifth N scale layout since 1984.

My current and new layout I have wired for both DC and DCC.  Of course my cost for the DC angle is greatly reduced in that parts migrated from an old layout. 

Wire sizes I run are 12 ga for main buss wires, 14 ga accessories and 18 - 20 for rail feeders.

My layout is 'round the room but divided into 10 separate modules that can be separated and moved if need be.  Each module has DC blocks for three mains running across the module shelf, feeder terminal blocks and disconnects at both ends to the right and left.  I have three power buss wires like double cab DC, with double throw center-off switches.  This allows one for DC running right now during build and test and one for Digitrax DCC.

As for choice:  DC is cheaper.  I have never spent as much $$$ as I have on DCC, and I still need more decoders.  But I think it is DEFINITELY worth it!!  You can run multiple trains on the same rail without flipping toggle-switches constantly from block to block, and lash-ups, helper engines for steep grades...on and on.  DCC.

that's my 2 cents

fritz

For the layout size

For the 4x8 size in N scale, you can use 14 gauge buss and 24 gauge for feeders, will save you some cash and for no longer than the runs will be youll never see the difference. Lowes and Home Depot have wire by the foot, no need to buy a 250 ft roll here. Use different colors for blocks, make a color code and stick to it. Keep it neat and do it right the first time.

One point I think is very important is to have a feeder to ever section of track, rail joiners should NOT be depended upon for power, only rail alignment. If you are using sectional track then consider soldering every other rail joint. 

DC or DCC is your choice but good wiring will make the layout fun either way. 

Rail joiners

If you have soldering skills from industry training, then rail joiners can easily be soldered and used for power connections.  If you don't then you are probably better off not to depend on them for track power.  Good solder joints are harder to make with rail joiners.

Soldering rail joiners on curves keep the rails in alignment and prevent derailments by eliminating kinks between pieces of rail.

There is not just one right way.

Terry