Sunday, February 12, 2017

Cab Bus - Final Touches & Tips

After installing (what I hope is) the last of the cab bus, it was nice to have my buddy Mike come down to help me set up JMRI, LokProgrammer software, and WiFi throttle on a couple of old laptops I had lying around. Now that I have my cool PowerCab box, and access to the LokProgrammer hardware, it's nice to have a dedicated laptop to use with them at the bench. Unfortunately, the plan to use an old Macbook as a dedicated WiFi throttle server was a #Fail, but we got Wifi Throttle set up on the Missus' computer - figuring we'd need to borrow it "only once a month at most". Now I can't wait to get to some fun decoder programming - thanks Mike!

Before he left though, Mike brought up a good point about the cab bus - "Why not install a simple switch so you won't have to keep going under the layout to plug and unplug the bus power supply?"

Why indeed.

I thought I was done with the cab bus, but in addition to a handy switch (which I'll get into below), I discovered a couple of helpful hints:

  • You cannot power the cab bus from a panel that is at the end of a branch.
Apparently it doesn't back feed or something, I dunno, but all I can say is that when I tried to connect the power supply to the panel at the end of the west end staging yard (to be able to plug it into an existing power strip - and switch), I got no power to the panel at the east end yard.
  • If you don't have enough power for the bus, the throttles won't work.
You'll know you need to add power to your cab bus if you wired everything right and your panel still doesn't work. It'd be a good idea to plan the location of at least one of your panels near an outlet.

Or, do what I did and use an extension cord(!).

But Mike was right - it didn't take but a few times to realize that I really needed an on/off switch. I decided to cut it in near the front of the layout (might as well make it as accessible as possible), right near where the cord bends up to route underneath the layout toward the panel:

At first, I was going to put the switch on the fascia but 1) I didn't want a toggle/switch sticking out into the aisle unnecessarily (especially right near the entry door), and 2) I couldn't fit an electrical box between the fascia and the benchwork anyway. But there was a very handy 2x4 already there, soooo....

I decided to just nail the box right to that. You can see the location above. Also note that I've cut the extension cord.

Note: I am not an electrician, but I've done some minor electrical work in my time - and I don't mind looking up stuff and asking for help. That said, do not consider this electrical advice nor rely on it. I'm just relaying what I did (and hope folks will chime in if they have a better way of doing it).

I've wired wall switches before, but this cord was different - there's no black (hot) or white (neutral) wire - and the color of the wire is all copper (rather than a dark brassy or silver). Of course, I figured this out after I cut the cord. And I needed know which wire to put the switch on. So, I learned a couple of things about a typical, polarized extension/lamp cord:

There  are two ways to keep track of the wire in a polarized cord: 1) the wide spade of the plug is the neutral side (corresponds to the white wire in typical house wiring), and 2) the grooved side of the cord (see those ridges on the left side of the cord above my thumb) is also the neutral side.

Ergo, the small spade and smooth side of the cord are the "hot" side (corresponding to the black wire). You put the switch on the "hot"/black/smooth wire on the cord.

Once I figured that out, the rest was easy straightforward: knock out the knock-outs on the back of the box, thread the wires through, wire nut the "neutral"/ribbed/grooved (aka white) wires together, and connect the "hot"/smooth (aka black) wires to the switch.

Pack it all in the box, add your faceplate, screw everything in and you'll have something like what you see above. I positioned the toggle so it points away from the aisle when off. All I have to do now to turn on the cab bus is reach under and throw the switch!

Of course, I discovered later that this is all a bit of overkill. I could have just followed these instructions and been done in about 5 minutes . . .

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