<<It is NEVER MIX
120VAC or House Hold AC power with LAYOUT WIRING of any kind. Layout
wiring is all LOW VOLTAGE. AC House Power is HIGH VOLTAGE.
The former is safe to touch. The latter is not.>>
I concur with
Mark on most of this, with one exception: DCC track power carries a signal and
therefore should be separate from other wiring.
1) As Mark says, always separate your high voltage
(110/220) voltage from everything else,
2) Separate track buses from all other wiring, A good
location for track buses (everything from the booster out to the track) is at
the back of the layout (thinking walk around here). While either twisting
wires, keeping them together by some other means, or keeping them far enough apart
to cause problems are all acceptable, keeping them together is neater and frees
up space under the layout.
3) Separate cab bus from all other. Jacks for cabs are
typically on the fascia, putting the cab bus near the fascia keeps it close to
where it is used.
4) All other – typically your AC and DC supplies
for building lighting, etc.
5) Wire routing:
a. Avoid spaghetti wiring – wiring bundles
should always follow the structural members of your layout – an example:
along L-girder, then up to a joist and along that joist to a riser, up the
riser to the roadbed, then along the roadbed to the point where the feeders
drop down through the roadbed. If you run a local track bus, the feeders from
your local distribution point to the track block should follow a similar route
to the local track bus and then feeders dropped down to the that local track
bus from the rail above.
b. Always anchor wiring bundles where they turn
(say from a joist to a riser).
c. Wiring should also have anchor points before
they are attached to a device (signal, switch machine, stationary decoder,
terminal strip, etc.) These anchors prevent a any tug on the wire somewhere out
on the layout from causing a break of some type (broken sold joint, wire pulled
from screw terminal, damage to device).
d. There is strength in numbers: always bundle wires of
a like type. I do a lot of electrical work on a DCC layout that was
originally wired by folks without a lot of knowledge. Retrofitting the
layout has been a bit of a challenge. In order to get the layout up the a
desired level of DCC performance we’ve had to do a lot of rework, and
sometimes one has to implement a temporary solution on the way to a permanent
one. In this case, we have often used scrap ends from surplus telephone
cables to provide temporary cabling. Once the layout has fully
transitioned, the wire scraps will be replaced by more permanent cabling
6) Except for modules, I would discourage the practice
of drill holes through joists or other framing materials (with the exception of
holes through the road bed for track feeders and other equipment located on the
surface of the layout). Drill such holes is extra work. Routing wires
through those holes results in the inability to easily re-route wires when
needed – particularly if the wire in question is a track bus and has
feeders soldered or otherwise connected to it – all those feeder joints
need to be undone in order to move the bus.
Some one also
mentioned the need to trace wires. One should never have to trace wires more
than once. If you have wired correctly, you have documented your connections as
you go. If you didn’t, the first time you have to trace a wire you should
document it and never have to trace it again.
As a hobby, we
seem to have lost sight of good wiring procedures over the years. If you want
some good resources for “wiring right”, I recommend the following:
1) Bill McClanahan’s “Wiring for Model
2) Any/All of Linn Westcott’s wiring articles in
the 60’s and 70’s, and
3) Both Volumes of Paul Mallory’s “Electrical
Handbook for Model Railroads”.
While I suspect
these are all out of print, they can be found occasionally on the used book
markets, and they provide vital insight into how to do it, and more
importantly, _Why_ you should do
In closing, I’ll
say that the smaller the layout, the less one needs to pay attention to this. However,
as soon as one gets beyond a simple module or the classic 4 x 8, one
needs to design, install and document.
It is also
interesting that if one does it right to begin with, one rarely has to maintain
things – the more you plan for the ease of maintenance down the road, the
less you actually have to maintain things.
Food for thought.