Unitrack rewire

ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Whether you're a master model railroader or just getting started, you'll find something of interest here.


ITS_MFRR est. 2010
Good afternoon all. I model HO scale and my layout is entirely Unitrack. Power is fed using 10 total feeder tracks evenly spaced throughout the layout. As you may or may not know, Kato feeder tracks are supplied with 24 AWG wire. Having recently added another loco to my fleet, I am now experiencing unexplained shorts. It has been suggested that I am seeing the effects of voltage drop due to insufficient wire gauge. I have a spool of 22 AWG and a spool of 18 AWG in the garage. I know opinions on this are widely varied, but any thoughts on using the 18 as a bus and the 22 as feeders? I run NCE PowerCab with no booster (as yet). Thanks as always!

Jason, northern Colorado


It may be simply that the additional loco has now overloaded your NCE powercab.

Try removing one or two of your other locos from the track. If the 'short' goes away then you need a booster.

Voltage drop on the wiring would not look like a short to the NCE, just the loco not running as fast.


ITS_MFRR est. 2010
After much discussion on this in the NCE-DCC yahoo group, it was determined I am likely seeing one of two things... insufficient wire gauge, insufficient power. Purchasing a booster is much more expensive than swapping out some wire... which I already have. I guess the thrust of my question is whether an 18 AWG bus and 22 AWG feeders will be adequate, regardless of power supply. If I have to get a booster, that's fine. It will just have to wait while I refill the piggy bank. PowerCab gives up to 2 amps. An SB3a booster would provide 5 amps. I'd hate to take the time to rewire with what I have on hand, only to find that I should have gone bigger.


Master Mechanic
If the layout is DCC, the largest gauge wire is always recommended for the bus. I personally use 14Ga wire for mine. I know several folks who have layouts even larger than mine using 12. I use feeders of 22Ga. 24Ga will be adequate as long as there isn't a long, (more than 3-4') to the track.

Voltage drop can cause many problems but, I would also make sure that you didn't get a wire crossed on one of the feeders.


ITS_MFRR est. 2010

I have a total of 6 locomotives. All are DCC. All have sound. All are parked in a roundhouse. All of the roundhouse stalls are live. At any given time, I only run two locomotives at a time. After some experimentation, I determined that each loco draws between 0.08 and 0.10 amps just sitting in the roundhouse... NOT having been started/activated. The only exception is the Bachmann. It does not have a start up/shut down feature like the MTH and Athearn locos. This weekend, I replaced all of my Kato wiring. I have 22 AWG feeders every five to six feet. The feeders are 8 inches long. The buss wire is 18 AWG. With no locos or rolling stock on the track, I show a reading of 0.0 amps. I put all the locos in their respective roundhouse stalls and then applied track power. Power Cab shut down. The rewire did not seem to do the trick. Is my next step a booster?

Thanks. Jason.


Loveably weird
Is my next step a booster?

Thanks. Jason.
I would add a booster. I would also rewire the roundhouse leads to some SPST switches to shut off power to all the leads except the one for which power is needed for a given loco at a given time. Having all those locos just sitting there is a waste of power.

BRS Hobbies

I would do as flyboy2610 suggested, using the switches to turn off the power to the unused locomotives in the roundhouse before adding a booster. You should be able to run 2 DCC w/ sound locomotives without tripping the NCE power cab short circuit protection so the problems that you are having is most likely due to the extra power being used by the parked DCC locomotives.

Best regards,

Affiliate Disclosure: We may receive a commision from some of the links and ads shown on this website (Learn More Here)

ModelRailroadForums.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com

RailroadBookstore.com - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section.

ModelRailroadBookstore.com - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.