I was at the store today pricing out wire for my HO scale power bus
and my forth coming NCE DCC system.
Is there a consensus on the guage for the bus wire and its track
I have often read 14-guage for the bus wire and 18-guage for the
Is 12-giage too heavy for the bus?
As always, thank you in advance for your help!!!
I use 12-guage for my NCE system, one for each rail (that is, one for
all of the "north" rails, a different one for all of the "south" rails).
I connect between terminal strips (one set for each, "north" or
"south"), drop 20-guage feeder wires to the terminal strips from the
track. I found a two-color 500' roll of speaker wire at Home Depot for
the feeder wires; red always goes to my "north" rail, white always to
the "south". Feeder wires every 3 feet - you can do with less, but
trust me, the difference is noticeable.
A few follow-ups.
 Regarding the 20-guage speaker wire. Do you maintain a strict max
length for each feeder wire?
 Did you terminate your bus wires? *** I was just reading the lengthy piece on terminating your bus. It
seemed to indicate that anything under 30' in length from the
booster / power source kept things simple and did not require
 Did you twist your bus wires together?
 Do you have an NCE booster as well as the power supply on your
 Do you run your LED lighting and switches off of your bus or do
you have a separate power supply for them? *** There was also information about twisting your bus to reduce
inductance issues. It didn't specify if 30' was the boundary length
for this concern as well.
Here's the link:
1. Length of feeder wires. No strict max, but then I put in a lot of
terminal strips, such that no section of track is too far away from one.
Longest feeder wires are probably no more than 3 feet or so. Note
that the feeder wire is solid wire, not stranded.
2. I run my bus wire between terminal strips. As it happens, my
"control center" is about in the middle of the layout, so I have bus
wires heading out in two directions from there, and they terminate when
they get to the last terminal strip, a distance of less than 30 feet in
either direction (layout is 12 x 18 around the walls with duckunder.
Duckunder is fed from both sides, but is electrically separated
approximately in the middle - single track only at that point. Each
half is in a different power district).
3. No. The bus wires are physically separated by about 15 inches or so.
The layout is basically a shelf layout, 27" deep, and the "north" bus
wire runs along the back of the shelf, the "south" wire runs a few
inches back from the from of the shelf.
4. I have the NCE SB3a Smart Booster (5 amp setup). The layout is also
divided into 4 power districts (basically, one on each wall). I also
have a wye, with it's own circuit board (think reversing loop).
5. All lighting and switch machines are run off separate power packs -
you can pick up used ones at swap meets for pennies on the dollar.
Friend of mine does the same thing. If you're going to use stationary
decoders for your switch machines, they will have to be tied into the
DCC system - afraid I don't have any experience with that, though.
Very Much appreciated!!!
You have given me a wealth of information that has cleared up these
lingering questions that I have had. I plan to follow your approach: a
12-guage bus, solid feeder wires, separate power for LED's and track
switches, and isolated power districts.
1) I can remember reading, a long time ago, a table for maximum feeder
length based on the gauge (the higher the gauge, the shorter the
feeder can be). And yup, it's on the same site I pointed you at
Note the link about
"track and wire resistance" on the same page, for more theory than
you probably need to know. As a rule of thumb - keep feeders at
3 feet or shorter, but you'd be surprised what you can get away with.
2) Never even thought about it. I don't think it's something to consider
unless you have very long runs (like 50 feet from the booster). Not
likely in all but the largest layouts. Frankly, I never even HEARD of
terminating a DCC track bus until I read your link.
Nope. I run them under the track side-by-side, and cut off a little patch
of insulation as needed when I need to stick in a feeder. Twist the feeder
around the bus, test, and if everything works OK, solder.
The power supply feeds the booster. The booster is the device that
modulates your DCC commands onto the track wires. You're always going to
have at least one of both.
These days, my switches are all driven from the rather wonderful team
digital SMD82 machines, which hang on the track wire. Don't know if they
work on NCE though, I'm a digitrax guy.
Lighting is on a seperate power supply in most cases, simply so that it can
be turned on and off seperate from the layout.
I wouldn't bother unless you have a long run to a spot in your layout, and
by long, I mean multiple tens of feet. Twisted bus wire is a pain to deal
with if you're going to be attaching feeders to it in the twisted section. *
I am pleased to read about your approach to attaching feeders to the
bus wire. I had seen that imaged and described in an article, and it
seemed like the ideal method. Your success using this approach has
confirmed my choice to go this same route. Ditto on running the bus
wires parallel but apart from one another like Matt stated earlier on
in describing his approach. I was hoping that the "twisting" method
was unnecessary - and it will be for me.
Space and budget will require me to build a small module extracted
from a larger layout drawing that I am presently working on. I am
going to complete every aspect of this module (no more than 36" x 8'),
get it to run perfectly, it will be a walk-around module design, and
see what happens from there. If space and budget allows for the next
module to be built and attached to the first one, I'll tackle all of
those connection issues when the time comes. I guess I will end the
bus wires with screw caps and leave a foot for each bus wire coiled
and hidden underneath the module. That will allow me to consider all
of my options going forward ... if going forward happens. The start-up
cost to dive into NCE is a bit pricey for me. However, there are two
local guys who operate their layouts on a weekly basis with a small
group of enthusiastic modelers, both use NCE, and, therefore, I
decided to buy into the same DCC system so I can operate at their
weekly sessions with confidence.
My sincere thanks to all of you for your replies and assistance!!!
I am a true hands-on learner which makes this early stage of
discussion (Q&A) a bit more challenging. But, I have taken down many
notes from these threads, I have a new DCC book on order, and I feel
confident that all of this will come together once I can make the NCE
purchase and get some hands-on experience. Plus, these local fellows
are very nice so I anticipate that they will be very helpful as well.
Don't really mean to play Devil's Advocate here, but I'd think 2-3 times
about the whole process before attaching feeders to the bus wire. A lot
of people do it, but to me it makes a lot more sense to put a spade
terminal on the end of a wire and attach it to a terminal strip with a
screw than to mess around soldering wires directly to your bus line... a
lot neater, and a lot easier to make changes as required. DAMHIKT.
The other Matt
H'm. Good advice, works well for small layouts, but for a room-sized or
larger layout you'll need several terminal strips. How do you attach one
of these to the bus? By soldering feeds to the bus. Each with a spade
terminal at the end.... ;-)
Actually, I daisy-chain the terminal strips via the bus wire (in effect,
making them part of the bus line). I've got a 12 x 18 layout, and yes,
I have a lot of terminal strips - one 6-8 post terminal strip for each
bus approximately every 3 feet. Gives me a lot of flexibility for
connecting feeder wires.
The other Matt
And I should have commented that I found your suggestion of only
connecting the terminal strips to the bus via soldering a feed and using
spade terminals to be preferable to the idea of directly connecting
every feeder wire straight to the bus. On my last layout, which was
larger than the current one, I connected most everything directly to the
bus, and it did get messy after a while. Too, it seemed like every time
I dropped a feeder wire from the rail and started looking for a good
place to connect to the bus, there were already half a dozen or more
connections nearby that I had to work around. On this layout, I tried
to bring a bit more order to things, mainly because the layout framework
is built on top of home built storage shelves, so I can't crawl
underneath it to do any wiring. The one mistake I did make: I put the
terminal strips on cross braces perpendicular to the front edge of the
layout rather than on braces parallel to the front edge. Thus, my
"north" bus line is harder to get to whenever I add new feeder wires.
Fortunately, I shouldn't have to add too many more feeder wires now,
though there are a couple of tracks that would probably benefit from
The other Matt
You will probably get slightly different answers from everyone, but here
is what I do...
The main buses on my system are 14 ga. The room is divided into two halves,
each being powered by a separate power booster, so a bus on each side has
a maximum length of 30-40 feet.
I use occupancy detector cards with up to four detectors on a card. From
the 14 ga. bus, I will use an 18 ga. feeder to the card.
Track feeders are 22 ga, but I limit their length to about a foot. If the
occupancy card is within that foot, the 22 ga. feeder connects the card
to the track on its own. If longer (though cards are almost always within
four feet of the track they power), I will use an 18 ga. wire to connect
the card to the 22 ga. feeder.
I prefer to have a feeder for each section of flex track, even though
the track has soldered joints. When a detection output feeds more than
one section of flex track, which is usually the case, I will use an
18 ga. wire ("sub-bus", if you will) from the card that runs to each
22 ga. feeder for the track.
To eliminate the "which Matt" confusion, I'll be MC ;-)
I do like the sound of this terminal strip approach a lot.
Let me be sure I have this correct. You cut the black bus. That, of
course, creates two separate ends to the black bus. You crimp a spade
onto these two newly created ends. You attach each of these spades to
each end of the terminal strip. You repeat the same process for the
red bus using its own terminal strip. And, you do this every 3 feet.
______black bus______[---------terminal strip---------]____black
_______red bus_______[---------terminal strip---------]____red
Do you lose some measurable voltage across each terminal strip???
All of these suggestions and "proven approaches" have given me
extraordinary clarity as well as wonderful options to follow once I
I would like to end each bus wire with a crimped spade so the next
module (assuming one can be added) is an easy attachment: spade to
spade with a simple nut and bolt assembly, perhaps.
How is the bus attached to the booster??? a spade? a bare wire insert?
The booster has a 4-hole plug. The two holes on the left are for power
in, the two holes on the right are for track power/dcc packets out. All
are bare wire inserted into the holes. Since I take off in two
directions from my center location, I take the two output track wires to
a terminal strip with spades. I use the two terminal posts on one end
for my "red" wire (the back rail in all cases), and the two terminal
posts on the other end for my "white" wire (front rail in all cases).
Note that these two posts on each end must be jumped together, since I
have the one input from the booster and two outputs to the bus (in each
case). The terminal posts in between *cannot* be jumped together (I
hope this is making sense!).
No need to try to get fancy when connecting modules. If your bus ends
in a terminal strip on each module, simply connect the terminal strips
between modules with a wire that has a spade on each end. On our
portable club layout this is basically what we do; we just make the
connecting wires permanent, with a male/female connector to snap
together when setting the layout up.
I've not noticed any appreciable voltage drop, but then I've never
measured it either. And yes, you have it correct.
Note that the terminal strips I'm familiar with
have two rows of "posts" - connect all of the posts on the top row
together with wire, connect the bus line segments to each end of this
top row. The bottom row, then, is where you connect the track feeders.
Such terminal strips are available at Radio Shack, or most any
electronic supply store. If you have an electronic surplus store in
your area, you'll certainly find them there cheap.
Perfect. The link/image helped a lot. I get it.
I thought these terminal strips ran horizontally. Now, with the image,
I see why you connect all of the top screws with wire to create a
horizontal strip. I like it. This is a winner for me. As you pointed
out, this will make the underneath quite clean and manageable. And,
with little to no voltage drop off from these periodic interruptions
in the bus wire, there seems to be no downside. Very nice!
Thanks So Much for sharing!!!
And, thank you for describing the hook-up process to a booster. I was
interested because I have sketched three separate modules that I would
like to consider for assembly (one at a time). I'm thinking an 8'
maximum length for each (with a 30" depth). The three modules together
would create the letter "L" (that is the only way this small house
could ever accomodate 24' of mainline track). The first one (which
would be the middle module) would place the power at one end and the
bus ends at the other end. The second module built (if it is actually
built) would be attached at the appropriate end depending on which
module was built second. That would either place the power between the
two modules or at the far end of the two module design. It would be
one or the other, of course. I think I would prefer to have it between
the two modules. Therefore, I like your approach of running a short
wire from the power to a spade to a terminal strip. That makes it
simple to relocate the power after each module is completed.
This is all very interesting. As much as I enjoy the trains and
scratch building bridges and structures from found materials and etc.,
I must admit that the wiring and the LED lighting are equally
fascinating for me - there's something fun about figuring out a
creative wiring scheme, having it look very clean (even though it is
hidden from sight), and then having it work properly.
All of this feedback is helping me a lot and giving me many ideas to
o output track wires to
I believe I get it. You start with a single pair of wires (a red and a
white - you bus pair). However, since you are centered on the layout,
you require two pairs to run in opposite directions. So, you split
your red and your white with the use of a terminal strip which then
allows you to send a red and a white pair in opposite directions to
power the rails, etc.
I am guessing this simple terminal strip would do the trick. The top
and bottom middle screws would NOT be used. The end pairs would create
two reds and two whites to travel in opposite directions for your bus
You're quite welcome. I'm far from being a wiring expert, but thanks to
a good friend of mine, I can at least understand this process, and
troubleshoot (to a degree) if something goes wrong. Too, with the
terminal strips (and I had a bunch of them left over from a previous
layout), it does make it easy and simple to add track feeder wires as
needed. Just last week I dropped additional feeder wires on three
adjoining sections of track; underneath it only took a few minutes to
connect all of them to the appropriate terminal strips, and I was
confident that all would work correctly.
Incidentally, note that you can combine two feeder wires into one spade
terminal (I always solder and crimp on spade terminals, just as a matter
of course) before attaching to a terminal strip. This allows you to use
shorter terminal strips, and if you happen to have a lot of drops in one
area, you don't have to join two or more strips just to accommodate all
of the feeder wires.