How do you get 208 voltage?

Answer 1

208 volts is the phase to phase voltage on a three phase low voltage system. In a split single phase service, the voltage is 120/240. In a three phase service, the voltage is 120/208. This is due to using a different transformer configuration. In the above, the first number is the phase to neutral reading, and the second is the phase to phase reading. For example, 120/240 and 120/208 both provide 120v on standard receptacles, but when using a dryer, or hot water heater, for example, that appliance would be using 240v or 208v, respectively.

Answer 2

The key to understanding this is "Phases" and supply configuration.

there r 2 types of supply Transformers, "Y" and "delta" /_\ = triangle

Each one produces 240V single phase across each coil.

In a Y config connecting to 2 legs of the Y produces output from 2 coils that r 120° out of phase. The resulting voltage is 208 volts instead of 240V.

If u connect to a leg and the center u get output from 1 coil only = 120V.

This is why 208 labeling is seen as 208Y/120

Normally, all 3 legs r used and the result is 208V 3 phase.

For a Delta configuration connecting to any 2 end points yields output from only one coil which is 240V single phase. 120v is obtained by center tapping that coil and connecting center to end.