# Formula to Calculate Current in 3 Phase circuits when watts or HP is known [With Examples]

In this post, you’ll learn the basic formula to calculate current in 3 phase circuits when either of the watts, kilowatts, or horsepower is known. Let’s first check the formulas:

Let’s solve some examples to better understand them.

### Formula to calculate current in 3 phase circuit from watts

Find the current which will flow through the circuit which has a 1000 watt load at the power factor of 90%. The operating source is 3 phase at 400 V.
From: I = P / (E * PF * 1.73) = 1000 watt / (400 * 1.73 * 0.9) = 1.60 A

### Formula to calculate current in 3 phase circuit from kilowatts

Here is formula is similar as we did it previously, just the factor 1000 is multiplied in this case.

### When HP is known

Determine the amperage loads of a 2 HP, 3 phase motor at the power factor of 85% whose rated efficiency is 90%. The voltages are 230.
From: I = (HP * 746) / (E * PF * Efficiency * 1.73) = 0.483 A

So that was all about 3 phase current calculations.

You can learn the calculation for single phase here.

### One thought on “Formula to Calculate Current in 3 Phase circuits when watts or HP is known [With Examples]”

• March 20, 2018 at 7:49 pm