Combining my MTH 4000 with my Lionel ZWL transformer on my layout

What are you trying to accomplish by combining the transformers?  I think there are some issues with using the ZW-L with DCS.   I don't know the answers, but I think this info would be useful for those who might be able to help.

I don't think you can do that as the ZW-L is not a pure sine wave transformer, The Z4000 is but I'll let the experts provide the final  and correct answer to this.

The major issues are that the transformers need to be in phase, and do not under any circumstances connect both of them to the same section of track at the same time. Not a good idea to have two transformers in series or parallel with each other.  As long as they are connected to sections of track or loops that are electrically insulated from each other, you should be OK.

@Landsteiner posted:

The major issues are that the transformers need to be in phase, and do not under any circumstances connect both of them to the same section of track at the same time. Not a good idea to have two transformers in series or parallel with each other.  As long as they are connected to sections of track or loops that are electrically insulated from each other, you should be OK.

In addition, be sure there's no place where an engine could cross electrical districts and get power from both transformers at the same time. 

We run both on our layout, but have both ground and hot completely isolated with 4 double pole double throw switches. We have two major sections of track that are electrically isolated but physically connected, so we are vulnerable (ie not TOTALLY idiot proof) to possibly crossing electrical districts. The rule is to never have both transformers turned on  at the same time.

We have found some interesting quirks between MTH and others, depending on which transformer we are running, but remiain very careful about max voltage on the MTH 4000 which exceeds the Lionel by 3-5 volts.

It seems the MTH stuff is much happier with the full sine wave.

Ben