Monday, June 27, 2022

SP Jawbone Branch (Part 31) - Wiring Owenyo Modules

Moving on from the last post (SP Jawbone - Part 30), it's time to start fabricating and installing the electrical wiring and cabling to power the modules.


Electrical plan for Owenyo

I started by disassembling the Owenyo #1 and #2 modules and one at a time moving them over to the support 'saw horses', which are boxes with a pair of 2x4s where I built the modules originally last year.

Drilling the Feeders

The feeders need ~0.075" holes for the ~1/16" 22 AWG wires with insulation. Holes were drilled outside of each rail section along the module. Marks with a black Sharpie for "North" and "South" rails with a simple "N" or "S". The north rails are to be wired with black insulation and south rails with red insulation. Marking the feeder holes makes it much simpler to prevent any cross wiring.

Feeders on the SG pit going down into the engine-transfer pit at East Owenyo.

Once the module is flipped over, the holes are marked on the bottom as well. Currently, as the modules are simple track-wise, I don't plan to run separate bus wires for each track (Main, Siding, House Track, etc) and simply connect the feeder 'drops' to the same bus wire pair.

Installing the Feeders

Road crossing between loading platforms at Owenyo with feeder holes marked and wires installed.

The feeders are made from 22 AWG.  At LMRC normally we cut the feeders between 12" and 18" long, stripping one end about 1/4" to solder to the rail and the other end about 1" to wrap around the bus wire and solder. On the Jawbone, I've decided to conserve a bit more length, as I don't want huge amounts of wire that I'll have to snug up to the bottom of the Owenyo modules. I made sure to leave an inch or two more length than I roughly figured would get the feeder to the back edge of the module, where the bus cable will be run.

Omega Feeder Wires (a.k.a. Cross Feeders for Closure Rails)

Omega wires with both ends threaded up through the feeder holes.

Omega wires are called because of their shape, that of the Greek omega character.  The purpose of these wires is to supply power from the stock rails to the inner closure rails of the turnouts.

I also marked these feeder holes on the bottom of the layout so when I was doing the underside work, there was no confusion as to what they were for.

Bus Wiring

The bus cable is made from 18 AWG and both ends are stripped and fitted with Molex pins crimped in place. The connector housings on the modules' west ends are fitted with male housings and female pins, while the east ends are fitted with female housings and male pins. The pins can be mounted either way in the housings. I decided to standardize the pins and housings in this configuration because after some testing, I found it was easier to remove the pins from the housings in this configuration.

Soldering It Up

With the modules inverted on the 'bench', I worked out the routing of the feeder wires. I drilled ~1/4" holes in the MDF cross bracing to keep the wiring up 'inside' the module as much as possible, keeping it from hanging down getting caught while working on it, moving the modules, or later over the staging yard below and catching on equipment.

Generally, I try to keep the feeders separated where they connect to the bus wires. This is to keep anything from rubbing or shorting when I'm working on it. Eventually I'll cover the exposed joints with liquid electrical tape ("Goo", no - not the Walthers kind!) or shrink tubing. However, the "Goo" is much easier to apply after all is said and done, and you can't thread new shrink tubing down to the joint.

The bus wires are de-insulated for short lengths between 1/4" and up to about 1" by cutting around the insulation with my No.11 Xacto blade and then either peeling the wire off by laying the No.11 down a slicing a strip of the insulation off, before unwrapping the rest off for the exposed section. The other option is to make the two radial cuts around the wire, and then use the point of the No.11 to slice a cut down to the conductor and again peel off the whole insulator section in one piece.

Either way, the main bus is exposed and I wrap the 22AWG feeder wire tail around the exposed bus. Once a section of the modules' bus is wrapped and ready, I solder the joint. Usually at LMRC we'd use larger Wattage soldering irons for this, but at my home shop where I'm working on the Jawbone, I don't have one of those, so I'm using the American Beauty Resistance Soldering Iron station to good effect.

Applying the 'Goo'

At this point, I'm not applying the 'Goo' because I want to test everything and insure that I don't want to change any of the wiring, add any blocks, etc.

I can see that I pre-wired the Water Tank leg of the wye too soon, and if I want that to have a cut-out switch, then I'll need to splice in some more feeder wires and do so.

Feeders on the SG pit going down into the engine-transfer pit at East Owenyo.

 Also I noticed that I wired the North rail of the transfer ramp pit track (east end of Owenyo, not the trestle) to the frog of the House Track switch, so technically the North rail on the spur is actually the frog of the switch. I need to decide if I'm going to cut the heel rail of the frog and make it separate again, or change the rail to be wired to the frog. All other switches on the layout at the moment are dead-frog until I build the mechanism for throwing the turnouts.

Once all the above issues are sorted out, I'll go back through under the modules and apply the 'Goo' to the soldered joints and finish tidying up any loose wires.

Extra Bus Cable to the DCC/Throttle

I fabricated about 6ft of paired 18AWG black/red wires with a Molex connector on one end and spade crimp connections on the other end to fit to my old MRC 1370 DC throttle for early testing of the layout. This is wired to the same standard as the rest of the 6-pin connectors, Pin 1 and 2 are North (black) and South (red) respectively, so this cable can be attached to any module. I plan to just use 6-Pin connectors around the whole layout for track power, and add the actual connector pins and wiring as needed to get 12V DC+, lighting, 12V DC- (common), etc. if I want to light future buildings at Little Lake or Bartlett.

The NCE DCC PowerCab base plug will be initially placed roughly at the center of Owenyo/Mojave yards.  I may eventually get an additional small cab that could migrate around the completed layout.  I'll probably add a couple more cab plugs at the ends of Owenyo/Mojave and one each at Little Lake and Bartlett.

Adjustments to Track

After a year, the benchwork has some slight bowing or hogging, I think from the cross framing actually being tight and slightly pushing the ends up. I think much of this is actually the wood ties are slightly thicker and I didn't carve out enough for the rail joiners, resulting in a small 'ski ramp' at center joint at Owenyo (between modules #1 and #2). So I will be making some adjustments to the end of module ties and possibly adding shims if the top skin sheet itself isn't flat.

Interlocking Wye "Safety" Blocks

Because the wye tail is removable, I want the curved approaches to have block switches to turn them off or on easily. Normally if the tail is removed, I'll just have the approaches with the water tank and fuel tank/engine spot turned off, which will keep anything from making a dive to the floor.

Curved 'Engine Spot' track, easy wye leg. with notes on N & S feeder drop under the 'metal' firebox drip pan.

While photos show that a number of places the track has settled pretty deeply into the alleged "ballast", which is more dirt than ballast, but generally I'm trying to hide where the feeders connect to the rails.  Many places I've been able to hide it at road crossings, or in the case above, where the SP had put metal drip-pans to catch any fuel or fire dropping out of the engine when starting up after being left overnight at Owenyo.

SP 2758 "on-spot" at the engine servicing track at Owenyo.

The SP Trainline had a great story of a new fireman that had to take over warming up two 2900-class in Oregon for the days work.  The watchmen had left and both engines let their boiler pressures bleed down far enough that he had 'trouble' relighting them and getting enough draft.  The new fire wasn't burning all the fuel oil that he was putting into the firebox, and the burning oil dropped onto the ties and the story went south from there... it's a good read!

So it's pretty obvious why they put these metal pans under the where they spotted the engines firebox, and I'll be running my wires up to hide under the plates too!

Electrical plan for Owenyo

The wiring of the wye is going to break my regular wiring convention inherited from LMRC's training, which is to have the north rail always be the one that splits blocks off.  However, on the wye legs, the outer rail of the curve (towards the center of wye) already is gapped at the frog heels, so I won't have to cut more gaps.  

The electrical to the wye will obviously have a Molex connector which will keep the approach tracks powered. When the wye tail is removed, I will swap to another connector which is a set of jumpers which engages a switch to run the water tank track section.

Finishing West Owenyo

I still need to lay the west siding switch, which lands very close to the western edge of the Owenyo #2 module, so I'll be coming back to lay that switch and wire it once I get Owenyo #3 module built.  One advantage of this style of construction is that I can move ahead with other sections without building the next module.

One problem with this aspect of the wiring is that I do have to come back and do at least one more round of lifting the modules out to do electrical work after it "could have been done".  However, with the path that I currently need to get the lighting up and working and for that I might as well do the track wiring for what I have, I think it's still a positive outcome.  It keeps me wanting to build the next step and get progress.  Building the Owenyo #3 module, which will hold the NG transfer trestle would allow me to run a wire bundle from the door over to the existing layout.

In Closing

The layout has been dark most of the last year because the 'cheap' 12VDC power supply died shortly after I installed it to test the lighting.  Without the good lighting I'd come to expect during the testing, it really hurt the desire to go back and do all the wiring and lighting again.  Especially because the overhead work with the lighting is most of what injured my shoulder and stopped the work.  So rather developed into a double-whammy of sorts.

The way the lighting's been without the new main LED lighting.  Hoping to get the good lighting up again soon!

Wiring is sometimes some of the more tedious and classically 'thankless work' that must be done on any layout.  It's also being combined with the technical part of properly lighting the layout as well, so lots of work that doesn't really show when the layout is finished.  That said, it's good to be back to doing some construction and work on the layout and after testing the lights in Part 29, I can once again see the layout light up properly. 

I look forward to getting the wiring and dimmer panel set up properly to run the lights and enjoy the layout space again.

Jason Hill

Related Articles:

Jawbone Branch Index Page - All Jawbone Branch related articles

Jawbone Branch (Part 30) - Electrical Supplies

Jawbone Branch (Part 29) - New Lighting Power

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