Em. Generator Breaker off that feeding service rated Firepump controller/Transfer Switch..
Service from Transformer feeding service rated fire pump controller/transfer switch (same).
From Generator Since breakers on Gen. Set its a Feeder.
From Transformer to to Service rated control/Transfer switch its Service conductors.
Generator side its 3 hots & Ground.
Transformer side its 3 hots & Neutal.(250.24C)
Neural & Ground terminate together at this point ????
Any one else run into this???
If it's a delta generator, I hope it's a delta pump. If it's a delta pump, you don't need a neutral. 250.24(C) doesn't apply to delta panels, as the AC system is not grounded at any point.
Easy answer: don't run the neutral.