Wiring a 2020 Lionel PowerHouse 180 to a TIU.

Center wire of the PH180 is hot, the outside wire is common.

Both outside wires? There's two.

There are only two wires from the PH180, the 3rd position is empty.  No connection at the pointy end of the connector.

This is true for the adapter plug, but not for the cord feeding into the plug (at least on the newer models). I had cut off the adapter plug thinking there were only two wires feeding into it, one for hot and one for ground, that I could simply connect to the respective TIU terminals but after doing so I found there were three wires, despite the third position of the plug being empty. I guess my question is where to terminate that third wire outer wire, my instinct is that its redundant and should be connected to ground but I wanted to get a second opinion. I've attached a photo for reference:

I'd obviously use the two that are active in the adapter plug and ignore the 3rd one.  I have no idea what it's connected to.

I know for sure the older PH180 units have two wires to the plug as it's obvious from the wire and I've also see several with the plugs cut off and there were two wires.

I have not seen any of the new ones, don't know what the extra wire is for.

Thanks! I might actually bust open the adapter plug to see if/where the third wire terminates, just to satisfy my own curiosity.

So based on my investigations/tests, it seems that the extra outside wire is a "sensor" that double checks to make sure that the circuit is grounded (the small board inside the plug labels it as such). If this wire goes "hot", it trips and cuts power until the issue is fixed. Additionally, if not connected it trips after being turned on for a moment.  Seems one of my bricks must have come with the polarity of flipped or something, cause when I connect to the supposedly grounded wire to the sensor port, the transformer made a weird buzzing noise that sounded like the breaker was being flipped off and on rapidly; connecting to the "hot" inner wire (in reality the ground) fixed this issue (Additionally the LED does not light up in this unit, which could be related to the polarity being flipped). I've heard that these units have been known for sometimes shipping with the polarity flipped, guess I got one of those.

I'm pretty shocked that you'd have a mis-wired one from the factory after all the flap over previous mis-wired transformers.

Actually nevermind, just tested the other unit, seems this third sensor wire is supposed to connected to hot after all (no buzzing when connected to hot). Must be a check to ensure that track power is being delivered.

Given that there's no on-line manuals that I can find, I can't say what the other wire is for.  Since I don't own any of the new production, it's also not really a major issue for me.

I have a single TIU and just one Lionel Powerhouse 180.  The PH outputs alternating current, so it doesn't matter which lead goes to RED , isn't that correct?

If you never add another transformer to the mix, that would be correct.  However, if there's another transformer introduced in the future, than you have to be mindful of phasing the transformer so that the common is the same phase on all the transformers.

Thank you John