Electrical Formulas

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To Find  Direct Current  Alternating Current
Single Phase Two-Phase* Four-Wire Three Phase
Amperes when Horsepower is known HP x 746 HP x 746 HP x 746 HP x 746
E x EFF E x EFF x PF x 2 2 x E x EFF x PF E x EFF x PF x 1.73
Amperes when Kilowatts are known KW x 1000 KW x 1000 KW x 1000 KW x 1000
E E x PF 2 x E x PF E x PF x 1.73
Amperes when "KVA" is known   KVA x 1000 KVA x 1000 KVA x 1000
  E E x 1.73
Kilowatts E x I E x I x PF I x E x 2 x PF E x I x 1.73 x PF
 1000 1000  1000  1000 
Kilovolt-Amperes "KVA"   I x E I x E x 2 E x I x 1.73
  1000 1000 1000
Horsepower (Output) E x I x EFF E x I x EFF x PF I x E x 2 x EFF x PF E x I x EFF x PF x 1.73
746 746 746 746
E = Voltage
I = Amps
PF = Power Factor
EFF = Efficiency
HP = Horsepower

Note: Direct current formulas do not use (PF, 2, or 1.73)

Single phase formulas do not use (2 or 1.73)
Two phase-four wire formulas do not use (1.73)
Three phase formulas do not use (2)
* For three-wire, two phase circuits the current in the common conductor is 1.41 times that in either of the other two conductors.