Short cercuit

[santafewillie]

I only am familiar with DC and you didn't mention what you use. First, shorts in wiring just don't happen overnight without some outside force. If you haven't already done so, I would first start by removing all motive power and see if it still exists. If it's corrected, add them back one at a time until you identify the offender. I would also look at every inch of track to see if a stray screwdriver, paperclip, coin, or other metal object might have fallen across the rails. Next look for any rolling stock with metal wheels that might be derailed over a turnout. If you did any recent work under the layout ( I assume that's where your wiring is), look in the area you worked on to see if you might have accidentally bumped or otherwise dislodged some wires. Good luck.
willie