By Sparky, the Division Chief Electrician
(Reprinted from The Relay, 2014, Vol 6 Issue 3A)

When doing any large wiring project, remember to test your work frequently. Everyone of us will have some story to tell about the importance of testing our work as we go. Simply said, I’ve had to redo about 2 hours of work on two different evenings recently because I failed to do that.

The background story goes like this. One of our division friends had decided to rewire his home layout to make it more reliable. He had used the old adage that to convert a layout from DC two-rail to DCC was simply a matter of ensuring you had no reverse loops and you connect two wires from the command station to your existing two wire power bus. That served our friend well until he decided he wanted to make his layout more operationally oriented.

He asked me to help him with the rewiring. I agreed and crawled under the layout. After we had decided how to break the layout into five more manageable (and isolatable) sections, I got busy cutting and gutting the single main power bus. (You know a bare ground wire might be a good idea unless the worker ends up with a static charge on him. On several occasions, I drew enough static charge to shock myself.) The bare ground wire was the first to be cut and removed.

Since the power bus was feeding most of the layout, there were plenty of previously installed drops. Multiple drops within the power district are a good thing. Too many isn’t a problem; too few can cause operational issues.

Since I was rewiring an existing layout, I was going to reuse the existing drops. Here’s where we divert from best wiring practices as preached by the Electrical Committee. You should always follow a defined color coding scheme when wiring. Once under the layout, I assumed (and we all know what that leads to) that the red drops were all the same and the white drops were the same so I could wire the red drops to the red sub-bus and then to the red main power bus for that section and the same for the white drops to the black sub-bus and main bus. (Yes, I was change colors but I wasn’t going to go back and put in new black drop wires for perfectly usable white power drops.)

After spending two evenings wiring the sub-bus and the drop feeders in the Western Maryland and the B&O mainline sections of the layout, we decided to test those sections. Using the continuity tester (CT) showed we had a short. When using the CT with a lead connected to both rails, the buzzer should have been silent. It wasn’t.

So back under the layout I went and started clipping drops from the newly wired bus. After each clip, we tested (should have been testing after making each connection, not now). The buzzer sounded and I got more frustrated with each piece I was undoing, knowing after we found the problem I’d be spending another hour reconnecting these same drops. Finally, at the last pair of drops on the Western Maryland, the buzzer remained quiet. So I started back down the line, reconnecting pairs of feeders as my friend used the CT after each operation. What did we find, but a pair of feeders had
been made on top of the layout with the color drops reversed. After that issue was found, the re-connection process moved quickly and correctly.

The CT we were using was one my friend had made a couple years ago. The wiring on the piezoelectric buzzer pulled free and could not be repaired (it had been repaired several times during the past weeks).

A week or so later, I was on a roll and pressed on with more wiring of drops to the bus. As I got ahead and overconfident, Murphy stuck his ugly nose into my business again. Murphy came calling because I elected not to work with another person to check each new connection I made with the CT. I again ran into the same issue as before after I had done about twenty connections. We finally got the CT repaired and tested the C&O staging connections. BUZZ!!!!!!!

(And a blue cloud of words escaped my lips and rose from under the layout……..again.)

Clip, clip, clip……clip (you get the picture). Yes, another pair of miscolored drops had been crossed up by me. The wiring issue was resolved and the C&O staging power district was operational.

With those failures fresh in my mind, I arrived to help wire the B&O staging yard and yard throat. The yard throat was made up of five hand laid switches with dead frogs. We were going to power the frogs using the internal contacts on each Tortoise. Using the CT allowed us to determine which set of contacts to use and which input was for which polarity.

That was much more successful until we found we had one lead from the power bus to the internal contacts on the Tortoise not tightly connected. Using the CT, we were quickly able to diagnose the issue and resolve it.

The moral of this story is: do as is recommended and test often. Otherwise, you’ll need to allow time to redo your work.

I’ll be back with more electrical tales soon.

Sparky, your Division electrician