had a GFCI recepticle installed with a plastic cover. Transformer is 150 watt, bought a 6-light landscape combo, totalling 112 watts total. Added another 11 watt fixture. Has been fine for about a month but the lights stopped coming on at dusk so I checked the transformer and the plastic where one of the prongs is inserted has melted. I can still unscrew the screw but does anyone know why this would happen?
You may have overloaded the transformer. You have accounted for the total watts from the lamps but not for the voltage drop in the wires and connections and transformer efficiency. Buy a larger transformer.