250.92 issues

[Bjenks]

I got called in to an HOA because many of the tenants were switching to 10.8kW on demand water heaters and the electric utility was concerned that the service was going to get over loaded. I did a optional dwelling & multi-family NEC load cal and found that the 125A panels which is fed by a 100A breaker and #1 75deg Al cable was able to handle the load with the on demand heater.

When I did the muli-family NEC load and assumed all 8 units had on demand the load calcs came to 470A, but if you look at the service coming in you might be able to see that it is only a #4/0 Al 75 deg rated at 180A wire. The meter pak is an old ITE 600A fused disconnect with a bus going to 2 800A 4 meter buses with the 100A breakers. I would have to take all the ranges, dishwashers, water heaters, and refrigerators out of the load cals to get the service down to 170A! I was hired to determine how many of the on demands that can be put in per building, which is obviously 0. There first thought was I am crazy as they never had a problem in the 30 years they have been there. So I am a little stumped on how to move forward.

Second problem: Since there is a 600A fuse at the disconnect and I am not sure if the N is bonded to the ground (I have to assume it is without opening up the rest of the disconnect), I also have to assume they didn't bond the N-G on the 100A breakers after the meter. It is metal conduit up to each panel and each circuit is using conduit as EG circuit. If you look at the picture you will see they ran a neutral and ground conductor up to the tenant MLO panel. If you look closely you will see that both of those buses are tied together and isolated from the panel. Which leads me to believe they are using the ground wire as a path for the neutral currents. I measured the ground wire with a current clamp and had .5A, but then turned on the microwave and it want to 3A. I got to believe this is a big violation that needs to be fixed, but again they say after 30 years nobody has been hurt and no fires. Should I just write a letter and move on or push it or maybe it is OK and I am missing something. Any advice?