DCS Wiring Question

Joe,

Figure 12 seems to imply that there should be an insulator on all three rails between the blocks.  

No, it does not. It simply shows 3 separate blocks. You're reading too much into the picture.

Figure 13, however, seems to imply that only the center rail needs to be insulated from block to block even though a common is run to the rail opposite the hot wire

Figure 13 clearly shows that only the center rail is insulated.

Further, the last paragraph on page 58 correctly states:

Track Blocks

A track block is a section of track that is electrically isolated from other sections of track by insulating the center rail of the track section from the center rails on either side of it. There are good reasons for wiring layouts using track blocks.

Barry is so correct about blocks. At first my layout was one giant block. It does work.

Following Barry and others advice I added blocks. It really is something you should strongly consider. It offers many advantages. 

Pete,

Am I correct that I should only connect one "hot" wire from the terminal block to that loop (and not the feeder wire "drops" every few track sections)?

That's correct. You should use Hot and Common pairs of wires, one per block, in the middle of each block.

If this is the case, what methods can I use to promote power continuity throughout the large loop?

As long as your blocks do not exceed the recommended 11 track sections,you should have no cause for concern as regards voltage drops.

Robert,

if using Gargraves track, 11 sections is 33' of track.

If track joins are tight, that's not a problem at all.

The track is typically as good a conductor of electricity as is wire. The care for voltage drops is in the joins. There's only a minuscule real-world difference between 11, 10" track sections and 11, 37" track sections, as long as the joins are tight.

Jim Barrett, not I, is the author of the "11 joins per track block" guideline, however, I (obviously) concur with his thought process.

I am finding noticeable voltage drop along lengths of Gargraves, but using an AC voltmeter can't isolate points where it is occurring.  Since most of my blocks are very short, only in one space has this been a problem.

Barry and All Others,  Thank you for responding to my question.  I really appreciate the help.

Joe

RJR;

Couple things; First, is there a load on the track while you measure? If not it is near impossible to find the problem. Voltage drops at resistance points, but only as much voltage drops as is needed to flow current to the consuming item. Meters consume VERY little power.  Power up an engine or lighted Passenger car a few feet in front of your measuring location as you go along.

Next; Have you tried cleaning the track?

I have found my power problems always go away after a good cleaning.

In a pinch I've just rubbed paper towels on the track, You will be amazed at what comes off the track even if it looks clean.

I usually use a scotchbrite pad and scrub lightly with a dry pad. no cleaning fluid needed. I have 2 gondolas modified to drag a scotchbrite pad underneath one and a paper towel under the second. With  a good weight in the car it cleans the track in a few laps with no missed spots. I change the paper towel every lap, the first lap it comes back filthy every time.

Definitely tested under load2-motored loco & a string of lighted passenger cars.  Voltage reading on track at loco (end-of-block) is less than voltage at location of power leads.  Track clean.  Problem was "solved" a few years ago by adding a 2nd drop to the center rail of the block.  Definitely contrary to DCS practice, but it must be in phase with other drop because I get no ill effects and signal is strong.  So as long as that works I just run trains and focus on other things.

Theoretically, if a track joint or wire lead is bad, I should get at least a few millivolts across it, but do not.