So we have a 50 amp breaker feeding a subpanel with a 50amp and a 30amp breaker the 50 amp is picking up the original feeders to the apartment the 30 amp is for are inverter. The city says we need to change the wire from are 50 amp breaker in the main to are subpanel to #2 because there is potential for 80amps. Has anyone ever heard of this?
If I understand this correctly, one 50 amp breaker in the main panel is feeding an MLO sub panel which contains exactly two breakers, a 30 from the GTI and a 50 which serves the original loads?
In that case the subpanel bus is required to be able to handle a total current of 50 amps from the main and 30 amps from the GTI, even though the only possible load is the 50 amp feed out to the original loads. (The 120% rule.)
But in the situation you describe there is no way that the wiring from main panel to subpanel can ever be subjected to more than 50 amps of current, since the main panel and the GTI are feeding current through it in opposite directions. If this is required to upsized, it is an anomaly in the code which needs to be corrected, but I do not interpret the code that way.
IF any additional load might hypothetically be connected to the wire between the main and sub panel, it would be possible for that load to draw more than 80 amps and not trigger either breaker. But at no point along the wire, except at the idealized attachment point of the load, would there be more than 50 amps flowing.
This particular situation is one which has been discussed heatedly on this and other forums.
So, yes I have heard of that. And if the inspector cannot be persuaded by the above analysis, you do not have much of a recourse, IMHO.
