When Do I use these again before and after switch peices??? Joseph
They are only used to isolate rails electrically. In DC, you would isolate blocks. In DCC, you would isolate power districts. Both use them to isolate reverse loops, or to provide tracks where you can shut off all power for engines/cars that are not in use.
If you can give us a bit more info about your track plan, someone can make suggestions about where to place insulating rail joiners.
Place them where you want to isolate the power from (end of a yard track or end of a siding ect.) but if you have a double-ended track they you’ll need to put a them at each end of the section you want to isolate. Then if you want to have power to it use terminal rail joiners somewhere in the isolated track and use someting like the Atlas 205 connecter to turn them on/off. I use this method and it’s great for turning off power to a track and parking locomotives there.