Ok so first off we had to tie into three different generators today all of them in different places and none of them easy to get to. Ok punching bag time over. A little information about the hook up. All three generators work well, are CAT generators, outputing 210ish volts, 3 phase, first genny rated for 700A, other two are 1000A gennies. They are all well grounded to the same grounding rod (not all at the same time but one cable moved to the gennerator being used at the time). I have two runs of feeder cable going into the venue down the stairs and into my power distro which has metering readouts (did meter with a multi meter before hooking it up though) So here's were things get fun. Hook up the first generator tie the ground and neutral together do the run things work great, but that's not our generator so we need to move to another one. Same cables, same tails, same generator tech, etc... go into the new generator, the legs meter out fine, the phase ok light is on at the distro, but the internal meters are so confused they aren't even giving a readout. Split the ground and neutral and things work like a champ. Move to the last generator for rediculous reasons that are irrelivant and this generator is already hooked up to a set of tails but has no neutral tail so we hook up with the neutral and the ground all going into the grounded tail. Same no readout nonsense. Split the ground and neutral, tie in a neutral leg and lifes great. So what caused this? I could see something not working because there was no return line along the neutral leg, but then why did it work in the first place with the first generator. Anyone have any ideas?