Hi, Have I got one for you, this is a long standing problem, I have a workshop with 3 phase supply, the compressor is 3 phase, now this is the problem and I have had two sparks in to get it to work on the pressure switch, the main problem is no one seems to know where the two black wires that come from the pressure switch go to in the star-delter switch, the three main live feeds go to the right side and the feed to the compressor on the left, it works fine if you press the start button and it runs to the set pressure on the pressure switch and you see and here it click as if it was trying to turn off, but with the two wires from it going nowhere then it will not, if anybody knows please let me know, as I have someone watching the pressure and turning it off when it get close to the required pressure, thanking you before hand. Cheers Ernie.