Is there a Rule of Thumb for Block wiring when using multiple TIUs?

 A lot depends on how long your blocks are. How many trains are you running on one loop. Passenger trains will draw a little more current especially ones without LED lighting. Just turning on your smoke units you will need more power. There really is no answer. Every layout is different.

One channel can handle multiple electrical blocks. Unless you have a very large layout with very long runs. One TIU should be sufficient. Is all your trackage just the 2 connected loops ?  Are there multiple sidings or a yard ?

Can you elaborate a little more on the size of the layout and what you plan on running as far as an operating scheme.

Hello Dave!

Sorry for being so late with my response.

Below is an overview of my layout. The Red dots are the points where the track is insulated (center rail only). If you ignore the sidings, the layout (12 x 18 feet) is two simple loops, each divided into 4 blocks.....

I will have ZW's powering the loops through two TIUs with appropriate protection (TVS diodes,circuit breakers, etc.).

I want to run either Conventional or Command engines on either loop. I will not run Command and Conventional engines on the same loop at the same time.

Each of the blocks are wired through a relay (that is controlled by a toggle switch at a control panel), then directly to one of 4 distribution points. Each distribution point is (planned to be) connected to a Variable TIU output.

I LOVE running fairly long passenger trains (6 - 7 cars) and multi-engine freight trains.

I hope this helps.....please let me know of there's more info you need.

 I think you can get by just running 1 TIU.  Four channels should be sufficient for a layout this size. 

 Unless you prefer using the DCS remote running conventionally. You can leave all the channels set to Fixed and just use the handle of your ZW to run your train. Whatever voltage goes into the input of your TIU is all that will come out the other side.

Looks like a nice design. Using 2 TIU's  I'm guessing you are going to run in Super mode. The biggest obstacle in running DCS is getting a good track signal. On a layout this size I still think One is enough and perhaps just 1 ZW. The red mainline and green mainline should only take up 2 channels. The purple line ties into the green and looks like it gives you a reversing loop. If you plan to use this for conventional running. You could use one throttle of the ZW to power both channels. I  hate to see someone spend money on way more than what they may need. Again. Only you know what you plan to run and how. Don't know if while a couple of trains are running the main will you be manuerving cars around the yard at the same time ?

Hi Dave;

I agree with your recommendations. My only fear is this...when I used to set up temporary Christmas Village layouts (check out https://www.youtube.com/watch?v=xJdQB9fBzrA if you get a chance for one my Christmas layouts) I ran 2 trains per ZW. After about 2 hours of running trains the ZWs would get pretty warm. That's why my goal was to try to distribute power for single loop across multiple ZWs if possible and add DCS control.

And yes.....I was hoping to control everything from the DCS remote.....even the Conventional engines. I didn't have plans to run any trains in the sidings. They would mostly be used as staging areas for other trains parked and ready to replace those running.

 I'm thinking you have one of the new ZW's. The older postwar ones do run a little warm. A lot to depends on what you are running. The post war trains as well can draw a lot more current. Smoke units on the newer stuff draw a bit more if you use them but still probably well under 4 amps when running per engine.The fact that you were running DCS I was guessing you were talking newer trains that draw far less. If you never plan on touching the handles to run your trains. You might be better off just using 180 Lionel bricks when they become available. I have a rather large layout but not a huge amount of trackage. I run 2 TIU's in Super mode. No signal issues. 4 mainline blocks. 1 block is probably the eqivilent of your entire loop. I only use 2 channels of 1 TIU for this. The rest are for the different yards and service facilities.  I have only one power supply. Very heavy duty. Built in the mid 90's. Called the Max. Features 2 12 amp throttles. Once I figured out how to distribute the power to the layout. I've never run out of power. I do run only modern trains. The layout takes up a space of 22ft x 48ft.

Hey Dave......I really want to thank you for all your help! Using a simplified diagram, I think I'm going to do is this.....
1. I have 4 PW ZWs,
2. I have 2 TIUs and 1 remote
I'm going to connect these components like this....

This way I'm thinking......
1. The outer loop should have approx. 30 amps available and the train can be controlled from TIU1 via the remote. And if I want, I can run more than 1 train on the outer loop.
2. Same with the inner loop.
3. And I should have the option to run in Super TIU mode to allow trains access to any loop.

Whadaya think??

 Using postwar ZW's is not a problem seeing you already have them. I would use a 10 amp fast blow fuse or a PSX AC breaker available from Charles Ro and a few others just to be safe. The TIU channels are rated at a max of 12 amps.

Thanks for the heads up on that....last thing I want to do is blow out my TIUs!