Atlas O track - ground wires ???

Personally, I'm not a big fan of joiners with wires, I prefer the track power and ground to go directly to a track segment.  One less joint in the picture, and my experience with Atlas rail joiners isn't the best.

Back before I had a decent soldering iron almost all of my Atlas track wire connects were by soldering to rail joiners. However I made sure to use only the joiners with dimples and used needle nose pliers to collapse the joiner a little. The fit was tight enough to have to use gloves to press the joiner into place.

I have worked on five rather large layouts using Alas track using their rail jointers with wires solder on the joiner and have never had an issue.  Just make sure the solder joint is solid (I have not discovered a new one from Atlas that was not solid) and the joiner itself fits tight on the rails.

Also, the outside rails were not connected together on any of them.  Having insulated outer rails makes using insulated rail to trigger signals a breeze.  And all layouts use command control without issues.

Good luck with your build,

Don

Thanks for the question Ive been debating the same!