So if my genset is 45KVA and I'll just use one phase, what's the equivalent capacity that I can utilize from the genset?

Right now, my genset supplies the following:
1 phase to my office
1 phase to our dirty kitchen/dining/maid's quarters/workers' quarters
1 phase to the house.

Lilipat ko na kasi office ko so mawawalan\ ng load sa office. Mababawasan din yung load sa isa kasi lilipat din workers' quarters.