Hi, I just bought a 50 amp Cutler Hammer GFCI for my new Keys hot tub. There is a screw in the GFCI box for bonding the case to neutral. Would I use this neutral screw or use a ground wire to ground the box? Also my main service is a Murry. It has a neutral bar and a ground bar. There is a pigtail to hook them together. Should I hook them together in the Murry main box? Up to now, I have hooked all the ground and neutral wires to neutral. I have wired two new houses myself but this hot tub with neutral ground, is way out of my class. Any help will be appreciated.