# P

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#### Electronman

##### New Member
Hi,

I have heard that the formula which states the reason of using high voltage in mains instead of using high current is P = I^2 x R.
Can you tell me why and how that formula states so?
Is this formula states that too: P = V^2/R?

#### crutschow

##### Well-Known Member
Power transfered through a wire is P= I x V, thus the higher the line voltage the lower the line current for a given power transfer. Since the I²R loss in the line resistance is proportional to line current, then the line loss decreases with increasing voltage for a given power through the line.

#### Bob Scott

##### New Member
In North America, we have to use wire that has twice the amount of copper for the same length of circuit for our 120V house wiring as 240V European receptacles using the same amount of power.

But our incandescent light bulbs last longer. They have thicker filaments of tungsten.

Bob

Last edited:

#### RODALCO

##### Well-Known Member
True. I second that Nigel.

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