My 120 panels are 12 ga and the PO used 12ga extensions for a few feet to the j box on the roof and then 6ga down to the controller. I redid everything on the roof before I recoated it last year and I pulled on one of the the ext. connectors a little bit and out came the wire. I check all of them and another one came apart. The wires weren't pushed into the pins all the way before they were crimped. I cut out all the connectors and extensions and used 10ga thhn in hard pipe all the way to the j box and soldered everything. I won't have to worry about any of that again! Craig