A different buss wiring inquiry for a O gauge layout

The electrons won't know the difference.

The job will be neater than individual wires.

I can't think of any situations where a hobbyist would need to trouble-shoot a bus wire, anywhere along its run, but that fear (or concern) gets articulated here often.  Faults occur at ends of wires, where they are terminated inefficiently, or get compromised by the action of humans.  I suppose on a very large layout, if a mouse were to chew through a wire, it might take 10 minutes to find and fix the fault.

There seems to be an obsession here that results in occasional questions about wires, colored wires, gauges, topology, etc. My advice is just use what's available, keep it relatively neat, use whatever color you can find, use adhesive number labels at accessible terminals and joints, and use the heaviest wire you can afford.

Document everything. It doesn't need to be NASA-quality, just readable by yourself after a rough day at work and a pair of adult beverages.

Is multi-conductor wire in a jacket more expensive than the same lengths of individual wires?

Guessing you mean a cable with 5 wires in it, and not 5 single wires you put in a plastic tube?  Plus I am not sure what 'multi-wrapped' means unless again,  it is a 5 conductor cable.  If you use a continuous cable, at every breakout you have to get the wire you need out of the cable, and then that remaining length in the cable is unused unless it is going to another spot carrying the same control voltage.  You would have to cut the cable open at the spot you need that particular wire, and open it enough to get a serviceable loop of wire to reach to your connection, or open it up and terminate  all 5 wires on barrier strips, then start again with prepping the wire to continue on.  If you want neatness without a lot of work, I would suggest running single wires along a path as you need them, and then going back when done with the plastic wire wrap tube you can get at auto supply stores and stuff them all in there and just have that one or two wires poking out where they are needed.  I have used multi-conductor wire to go to a yard, where you have several blocks and the one cable only goes from your block switches to the yard area, terminate in a barrier strip if you are fancy, or just strip enough back to reach every point in the yard.  If not familiar, a barrier strip usually consists of a insulative base with metal bond points with a screw on each side, 5 terminals and 10 screws for a 5 wire cable.  You would cut open the cable, be neat and use a crimp on lug on each wire, or just put the wire under the screw, if the cable had to continue on, you would dress the end and put it on the barrier strip, and go to the next one.  You can also just cut the cable open and use the wire or tap into a wire that continues on.  You can also use wire nuts, but it sounds like you want to be really neat.  Crude drawing attached, hope this might help.

I have heard about self induction between two ac wires close to each other such as twin ac lamp type wires interfering with solenoids like those in a track switch.

Just in case it is possible I separated all my wires to my switch solenoids.  This was easy as all switches had a common wire that runs around the layout to all switches and all rail outside rails.  The wire for transformer voltage for each track switch comes from the push button switch on the control panel that has a 14 vac source.  This wiring method also was easier and used a lot less wire.

I do not know if the voltage from two separate ac track voltages will have self induction interference or not.

Charlie

I've have star wiring supporting my DCS and Legacy track power, 14 gauge color coded  to barrier strips.  I used individual stranded wire to avoid cross coupling issues.   I have 14 VAC for accessories and 12 VDC for LEDs/electronics.  I used 14 gauge Feeder wires to barrier strips and 18 gauge from the strips to accessories, signals and lighting.  Frankly I didn't worry too much about color coding expect for power feeders.    My experience is, except for power, the rest is mostly once and done.  I label the power barrier strips.  As you expand the layout, it's handy to know where the power is.

Also, when the layout turns-on some 14 VAC and 12 VDC feeds are immediately powering switches, ,signals, etc.   I also have main power toggle switches: one for 14 VAC and another for 12 VDC which bring lighting and accessories to life.  I also have under table lighting.  I use long power strips fed by 12 VDC to illuminate Department 56 houses, etc.  I used the D56 cords with LED bulbs and just plug them in under the table.

Tommy,

You stated feeding  4 Loops with a 5 conductor cable. Is the 5th conductor for a future loop or is it going to be used as the return for the feeders. If it is the return feeder it will be carrying (in amperage) the sum of all the 4 loops. So for example if each loop is using 2 amps the total thru the 5 wire will be 8 amps

……….john

Hi guys, thanks for your inputs both pro and cons.  I'm really mulling over the 5 conductor cable. Don't know what to do yet.  John, I envisioned 5 conductor cable to be used as 1 cables per loop and a common ground.  Tks.  Tommy     All comments are welcome.

Wire gauge ampacity charts are typically for wires in free air space.  Recommendations are based on voltage drop and heat generation.  A specific wire's temperature rating is based on how much heat the insulation can safely tolerate before melting.

When multiple wires are bundled together in a cable jacket, conduit or enclosed raceway:

• heat generated by each wire dissipates more slowly and
• heat from each conductor is additive.

Maximum safe current ratings are decreased when wires are not in free air.