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Here’s something I’m sure will make you scratch your head for a while.

After running my trains for a bit I noticed I had a power drop in a certain area, so naturally I found a good spot to drop some feeders and got them hooked up to my terminal block. I went to go flip on the power switch and instantly my power supply breakers tripped, so I assumed I hooked up my hot and common backwards. I traced my new wires and everything ran red/red and black/black and after confirming that everything was correct I flipped the power back on and boom, breakers tripped again.

At this point I’m getting frustrated and have no idea why my power supplies keep tripping so I take a breather and come back and look at my main terminal block and what I noticed blew my socks off. Everything I had wired up prior to today was all backwards! All of my hot leads from the track ran to black on the terminal block and all the common ran to red. I have now fixed my mistake and everything runs red/red and black/black as it should.

Here’s the head scratcher… how was my layout running perfectly fine with everything wired backwards? I’m no electrician by any means so if someone with my electrical knowledge than me could explain this I would love to know exactly how this was possible.

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If you are using Alternating Current for your power source(s), and if more than one source with a common connection among them, as long as these sources are phased with each other, then the electricity doesn't care what color your wires are as long as they are consistently connected the same throughout the layout.

Remember that AC travels in both directions and changes direction 60 times per second.

If you're using Direct Current, polarity matters more for some loads.

Last edited by SteveH

Sadly, I knew a person who I help with a layout who has since passed. It was all tubular, 2 ping-pong tables, 4 ZW transformers. The tracks were in theory split into 1/4 blocks. It would take near full throttle all the handles to get the trains to move. You could cook eggs on the top of the ZWs. There were tons of lockons, maybe every 3 feet. Only when I was ripping this out and replacing with fastrack did I discover, more or less at least half the lockons where wired reverse polarity. I found blueing, yes blueing of the rails and track pins in a few sections from getting so hot. How this did not melt and in some cases did but did not start a fire on the outdoor carpet the track was on, or the wiring burning up under the table is just insane. I saw a 4 foot piece of wire spliced 3 times- so that also contributed.

So, I know for a fact what you say is 100% possible and there are likely people out in this very forum who have at least one reversed. I know that the resistance of track pins and connections, can be such that it's high enough to heat, but not enough to stop a train.

Last edited by Vernon Barry

Actually three-rail engines run fine with the transformer connections reversed.

For conventional running, the whistle and horn controls on the transformer would have reverse function.

For TMCC/Legacy command, most engines wouldn't notice at all, one or two might have signal strength issues.

For PS/2 DCS, they would exhibit issues as you have to have the wiring from the TIU correct for them to run.

You are correct that Center rail hot is the convention, but AC motors and other electrical devices will work with either scheme (center rail hot and outside rails common or vice versa).  "Power" is running through both wires and all 3 rails.  It's not like DC where you have a ground even though some call it that, in AC its called Common and is electrically isolated from ground by the transformer.  With AC there are hot and common, but the power and current flows in both directions between these two conductors.

Last edited by SteveH

It’s true what they say, you learn something every day and I would have believed it without seeing it with my own eyes. I didn’t know the engines would know the difference either. I run Lionel Legacy and I thought everything had to be inside hot and outside common but apparently you can do the opposite like I did and everything still runs perfectly fine.

I’m still surprised that there was never an issue, mind blowing!

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