This came up in another thread. Here are the diagrams I was seeking that show how to wire a programming track directly into the layout safely. Wiring a programming track into the layout is very convenient. You'd simply take a piece of track isolated with gaps/insulating joiners, and connect it through a toggle. Toggle one way, programming, toggle the other, regular running. The idea is you run a loco onto the track "regular", then flip the switch to "program" do your programming, switch the track back to "regular" and drive the loco off. All very convenient. Problem: If you inadvertently leave the track set to "program" and try to drive a logo on to it, when the loco bridges the gap between the "regular" layout and the "program" track, all sorts of bad things can happen - decoders get reset, wiped out, even your system itself could get fried... So how to have our cake and eat it too? The trick is to use a 4PDT switch to create a 'bridge' section between the two. When set to regular, all three tracks (main layout, bridge track, 'program' track) are set to regular DCC operation. When set to 'program', the program track is set to program, the regular layout remains set to regular operations, and the 'bridge' track is completely dead - no power. This prevents the "oops" bridging of the gap. The original explanation is at http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=36389&REPLY_ID=372838#372838 (None of this is my idea, it's all user "jfugate" over at the forum linked here, credit to him.) There are two diagrams in that posting which are VERY helpful. I won't repost them here because they're nearly double the Gauge size limit... I think it worth going and looking at them "big size." Each shows a variant of how to do this. The latter including an LED to light up and indicate the state of the "programming" track. I myself will be doing this in my staging yard, where one of the tracks will become "programming". Personally, I'm using the first variation - I'm content to note state of the track by toggle position and don't need the extra LED... YMMV of course.