Free-mo Wiring

[macjet]

My current project is a three section 18' Free-mo module. I have the first six foot section built and on legs and I'm now working on the wiring.

Following the Free-mo standard I have terminal bars at both ends of the module to accommodate both the track bus and the accessory bus. Both buses are 12 AWG stranded wire. The Free-mo standard suggests (as any DCC project I suspect) that the feeder wires from the bus to the track be no longer then 6". With a 24" wide module and 2" foam with a centered bus I'm looking at a 10" feeder (no track center closer then 4" from the edge).

Can I run dual track buses off the same terminal bar parallel to each other to reduce the feeder wire length? Would there be a voltage drop?

Thanks.

 

[hotwinger]

That's kinda what I'm doing on mine now. I'm creating sub main buses all with 12 AWG wire so I get no power loss. And to keep my feeders under 6" since i'm using 22 AWG feeders.

 

[kjd]

My track buses go end to end as you can imagine. I have feeders to every piece of rail (even switch points) that go from the rail to the bus. Feeders don't go to the end terminal strip. I strip a little insulation off the bus wire and wrap the feeder wire around the bus wire and solder. I can't remember but I don't think I put any insulation over the joints but made sure they were not next to each other. I think the terminal strips are there because it is much easier to fix polarity issues (which have caused problems at every Freemo meet I have participated in.)

 

[UP2CSX]

Mac, four more inches of 12 gauge wire will make no difference. You'll have plenty of capacity and no voltage drop. Free-mo wiring standards have always seemed a bit excessive to me but I guess that's to cater for a situation where you might have 20 or 25 modules connected together.

Anything you can do to reduce the total bus length will reduce the possibility of voltage drop. Running two buses off the same terminal strip, as long as the total length of wire would be less than as single bus, will be a positive step.

 

[kenw]

quite honestly, you'll have a bajillion times more voltage drop at rail joints unless you solder them. Likewise at any wiring joint/connection. as Jim said, the voltage drop delta of 12" vs 16" of 12 g wire is darn near unmeasureable.

don't forget, the rail itself is a farily large effective diameter conductor as long as it is soldered at the joints.

and there is no real reason that the bus has to remain centered, is there? In my book, it can move closer to the rails (towards front or back of module) where the feeders attach if you are really wanting to keep each feeder under 6". Sure the bus gets a smidge longer, but at 12awg, that's really not an issue.