I have a problem with my lighting system on my back patio. I have three ckts fed by two source leads that are attached to my Txfmr. The txfmr is an "I-Force" multi-tap 12-20V from Unique Light. One ckt has 17 10W lamps and two 30W spots (approx 50 ft wire run)connected to the 13V lug. The second ckt has 14 10W lamps and 2 30W spots (approx 70 ft wire run)connected to the 14V lug. The Txfmr says that there should be no more than 360W max per voltage source so I'm good there.

When this problem started was when it was raining quit a bit and the underground connector towers filled with water. The gnd lugs and wire were fried on the txfmr.

I moved the boxes above ground, filled the wire nuts with no-ox, and taped up tightly. I repaired the txfmr using new lug strip and replacing the 10 gauge wire gnds that were burned leading to the tx itself. All connections were soldered, crimped and sleeved with shrink wrap.
It is controlled by a light sensor and I have the source power going through a GFI outlet and timer in a separate Nema 12 box.

I tried it last night and this morning it show signs of excessive heat. Wire coating burned back about a 1/4 inch and charred on both ckts.

There was no problem with the system and worked fine with no problems for the first 7 months, then we had a really wet fall and it hasn't been right since. It took a while to find the flooded boxes as they only flooded when it was raining long and hard. I was sure that this was the problem.