1. Calculate the load current on the 208V side

The load current on the 208V side will be less than the 1200A load current on the 120V side, due to the higher voltage. The ratio of currents is:

I208 = I120  (V120 / V208)

Where: I208 is the load current on the 208V side I120 is the load current on the 120V side V120 is the voltage on the 120V side V208 is the voltage on the 208V sideSubstituting the given values:

I208 = 1200A  (120V / 208V) = 720A

2. Calculate the number of sets of #600 AL MC Cable required on the 208V side

The current-carrying capacity of #600 AL MC Cable is 600A at 90°C. Therefore, the number of sets required is:

Number of sets = I208 / 600A = 720A / 600A = 1.2

Since we cannot have a fractional set, we will need two sets of #600 AL MC Cable on the 208V side.3. Calculate the transformer size

The transformer size is determined by the load power and voltage. The load power is:

P = VI = 720A * 208V = 151,200W

The transformer size should be at least 151,200VA. The actual transformer size selected will depend on factors such as efficiency and load factor.4. Step-up transformer

The step-up transformer will increase the voltage from 120V to 208V. The transformer ratio is:

Turns ratio = V208 / V120 = 208V / 120V = 1.73

The step-up transformer should have a turns ratio of 1.73 and a power rating of at least 151,200VA.5. Step-down transformer

The step-down transformer will decrease the voltage from 208V to 120V. The transformer ratio is:

Turns ratio = V120 / V208 = 120V / 208V = 0.58

The step-down transformer should have a turns ratio of 0.58 and a power rating of at least 151,200VA. Flag for review