Switching Between Blocks which use Different Transformers

Joe,

Phase is important.  Make sure that:

1.  All transformers are plugged into the same house circuit, i.e., they share the same circuit breaker.  Power to a modern house usually consists of two hots and a neutral.  The two hots are out of phase.  Adjacent breakers in the box alternate which hot they are on.

2.  Use insulated pins/connectors on the center rail between different transformer power blocks.  Use regular pins/connectors on at least one of the outside rails.  This connects all the common posts from the transformers.  If you have any polarity issues you will see a short.

3.  Plug your transformers in one at a time.  The transformer plugs are polarized so plugging them in should not be an issue.  If you have a plug where there is not a ground pin and the two prongs are the same then you need to be careful.  You have a 50% chance of getting it right when you plug it in.  If you get a short just flip the plug over AND mark it so you can insert it properly the next time.  Not all transformers are wired the same so you may have to switch hot and common wires at the posts.  Correct the fault and continue plugging in transformers.

4.  When running trains you may see sparks as the power pickups cross over the junction of two power districts when there is a difference in voltages.  I have not had any problems with conventional locomotives nor command control (TMCC).

Jan

Thanks Jan,

One question. Why would you want to connect all the common posts from the transformers?

The usual way to do what you are describing is to just insulate the center rail. When you connect the common post to the outside rail, all the common post will be tied together. If you insulate all three rails, there will be no way to phase the transformers. When a train is crossing the insulated joints the common posts will be tied togheher through the train and there could be a lot of arcing because the transformers were not phased. 

When connection multiple transformers together as you a are planing to do there an extra safety precaushion that you need to follow. With one transformer plugged in and one unplugged, when the center rails are connected together by the roller assembly crossing over the insulated joint, the prongs of unplugged transformer may become energized.  Maybe at a voltage higher than the house power. I recommend the use of a power strip with a switch on it. Plug all the transformers the in and then turn the power strip on. If a plug needs to be reversed durning phasing, turn the power strip off, reverse the plug and then turn the power strip back on. I would never leave one transformer unplugged with others plugged in. 

OK, so all the blocks that have the crossings should NOT have the outside rails insulated. I do understand that the center rail should be insulated.  This will also be the case between blocks using the same transformer output. Can you still insulate the outside rails between blocks using the same transformer output?

I think all the transformers have ground pins.

Yes, the only time that would cause you trouble is you had a loco which could end up trying to draw outside rail power from one side of the insulation and center rail power from the other side of the insulation. Then it will just not run. Hard to think of a loco that would put in that situation.  Maybe something with traction tires. If you are running DCS this would also stop the DCS signal. Should be okay with TMCC. 

Lionel's phasing video is a very good one (as pleasurable as instructional can be really) . I did this in 3rd grade over the phone .

https://www.youtube.com/watch?v=iASQfnE6pCk

   All power should be phased, age has nothing to do with it except the modern pug's flair for polarizing, and you should to check anyhow. Using many muli-taps of different transformers together can have some combos to be avoided, or used to be "tricked out", but you've got to learn the basics first, #1 is phasing.

   Call one your "master transformer" and phase all others to it. Run commons together nearby at a bus if you can.

   Any unplugged transformers plug end, still wired to your setup, will be "live" if another is plugged in.