I am doing an appliance repair course and they made a point in the material that appliances that use 240 volts, lower the overall amount of current they draw from the service lines. I do not get the concept why this would be so, will you explain How?
06smith

There may be better ways of explaining this, but this is how I think about this situation.

A 1 HP motor uses about 750 watts, and since electrical power is measured in WATTS and mechanical power is measured in horse-POWER you could say that 1 HP is the same as 750 watts.

If you use Ohm's Law, you know that Watts = Volts x Amps, so with algebra, Amps = Watts / Volts.

Thus, if you run a 1 HP motor at 120 volts, it would draw 750/120 or 6.25 amps.
However, if you run the 1 HP motor at 240 volts, it would draw 750/240 or 3.125 amps.

So if you double the voltage, you halve the amperage for a given load. This also works for resistive loads such as heating elements.

I hope this helps,
WallyH