If a 230 volts load is connected to 240 volts power source, what is the minimum voltage that can be supplied to load as recommended by NEC?

NEC recommends the maximum voltage drop should be less than 5% for both branch circuit and feeder.
5% drop = 240 x 0.05 = 12 volts
The minimum voltage that can be supplied to load is 240 – 12 = 228 volts