I have my medium sized layout divided into 2 blocks with each one assigned to the TIU Variable channels on my TIU unit. Do I need to isolate the outside rails along with the center rail where the 2 blocks meet? I did this on the previous layout and it seemed to improve operation, but is kind of a pain since I am using Fastrack. Just wondering if it is necessary. Thanks!
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No need to isolate the outside rails.
Thanks-that was just the answer I was hoping to hear!
It was tailored to your query. 
John has it. Never isolate outside rails.
shackdaddybass,
This is the 2nd or 3rd time I have run across different people wanting information on whether to isolate the outside rails, where are you guys getting this misinformation from. Never isolate the outside rails, Marty & Guns are absolutely correct, can't understand where this outside rail misinfo is generated from, no place in Barry's book or on the OGR Video guide to DCS, does this kind of outside rail education appear.
Seems some of the guys are wanting to make this set up harder than it actually is.
PCRR/Dave
Dave,
no place in Barry's book or on the OGR Video guide to DCS, does this kind of outside rail education appear.
Not exactly... 
Page 58:
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.
Page 62:
Isolate all track blocks from all other track blocks by ensuring that the center rails of each block are isolated from adjacent blocks. It's NOT necessary to isolate the outside rails from block to block.
Page 148:
Continue checking the voltage at the entry to the terminal block and at the exit point where the terminal block is connected to the tracks. Then check to see if voltage, and the DCS signal, is leaking between blocks that should have their center rails isolated.
This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!
I have to wonder is it's bleed over from Using Isolated outer rails to trigger accessories?
People do mix things together in the mind over time.
I read Barry's book before I implemented DCS the first time and understood I only needed to isolate the center rail. However, whenever my locomotives moved from one loop to the next via a pair of Fastrack turnouts, my locomotives would go haywire-uncontrolable speeds, bells and whistles on constantly, and sometimes just shut down. Using a Dremel I isolated both outside rails. From that point on, everything worked great. I did have a jumper between the grounds at the terminal strip for each TIU channel. Never could figure out why this happened!
Barry,
Your book indicates that is it not necessary, to me in NASA engineering terminology
that means don't do it. You wrote it so you know better than anyone else what the intended meaning really is however. Russell's idea might just be right on the money however! Shackdaddy it sounds like you got a couple of the FT switches that were wired incorrectly, some of those switches were sold a while back.
PCRR/Dave
Dave,
Your book indicates that is it not necessary
While your statement is true enough, it doesn't say "don't do it" for a reason. That's because it's not a "rule" one way or the other. It's an option that can be used or not.
The only plus to connecting Common to both outside rails is the assurance that the engine will always have a connection with track Common. This is for power m,ore than for DCS signaling. However, the converse is not true, i.e., it's false that not connecting to both rails will cause a loss of the DCS return path.
The only minus is that there is nothing left for an outside rail-activated signal or trackside accessory.
On my own layout, I compromised by using one outside rail for the DCS signal return and joined both rails only where needed to ensure availability of a Common return around switch tracks.
From an electrical distribution standpoint, having the outer rails connected reduces voltage loss between ground drops. Under DCS, there are some locos that have lousy grounding, so having both rails connected might be of some help.
I used fastrack and I have two blocks. One Outside Loop connected to the left side of the Z4000 and the inside loop connected to the right side. There is a gap between the center rail where the turn outs connect. I just removed the jumper wire. Everywhere I put a power drop from the center rail I also put a ground. I ran these drops to a terminal block. One for the center rail wires and one for the outside ground. I connected each terminal block in series and connectd them to the TIU. I ended up with three sets of terminal blocks for each loop. Maybe I over killed the number of drops, I put a drop on every third section of track. I got 10"s all the way around my layout that measures one scale mile per loop.
Dave,
"The only plus to connecting Common to both outside rails is the assurance that the engine will always have a connection with track Common."
Have had to do that in many locations Barry, rubber tires just kill us at switches!
That does happen, but it's more than traction tires. If at each end of a section, switches can leave a section dead. A long train's cars bridges the gap, but run a 0-4-0 deadhead, and they show up.
Traction tires on certain loco configurations and uneven track can cause brief dead spots, that only show up when running dead slow.
Robert,
From an electrical distribution standpoint, having the outer rails connected reduces voltage loss between ground drops.
Really? I don't think so.
I do.
Robert,
Ok, however, you're mistaken.
No.
Robert,
Fine, have it your (wrong) way.
Barry,
I get what you are saying about being an option for power, I never really considered that before. I was thinking more along the signal strength line and could not see any reason for doing it at all.
PCRR/Dave
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