I have a sprinkler customer who asked me to look at his lighting. He said he has certain areas not coming on. He has a 1200W CAST transformer. After throwing breakers and checking, I figured out that the two legs going into the #4 common port were the ones not working. After I put those two legs into another common port, the lights worked. I noticed that the #1 common terminal burnt and charred and pushed off to the side and that the common field wires were spliced directly into the transformer wire. I am assuming that the original installer did this. So, I now decided to get the #4 common terminal out of there and this is what I found (pic). The wire was totally burned up. I pulled enough of the #4 wire down from the transformer to cut off the burnt wire and splice into the two field commons - all lights now work. However, I do not feel comfortable leaving it this way and the homeowner agrees. Entire system is incandescent but it doesn't appear that the legs are overloaded - a couple of 35w mr16's and path lights per leg - no more than 5 fixtures per leg. System is less than 5 years old. I am going to give him an estimate on replacing the transformer (I use Kichler), and I will also suggest LED drop ins for his incandescent fixtures. The design is good and I have always been a fan of the CAST fixtures. I am just trying to figure out what the hell is causing all of these common ports to burn up? Never encountered this before.