Layout shorting out

[nachoman]

Fred's post was excellent. One other thing to check - are your real gaps filled with something, or are they just gaps? And I assume you are using pc ties for the turnouts? all it takes some microscopic bit of conductive material in that gap and you have a short. I built a turnout, had a short, and it turned out that I hadn't sliced through the copper cladding quite all the way. I needed magnification to see it. If your rail gaps have nothing to hold them open, perhaps one rail got bumped and a gap was closed? I always put thin strips of styrene in my gaps.