Calculation

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LANDON1

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What is the formula to find out what the amperage of a 30kw heater, 3 phase at 120/208 volts would be
 

augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I= P/E x 1.732

If applicable, don't forget 422.10 & 424.3 when selecting a conductor
 

skeshesh

Senior Member
Location
Los Angeles, Ca
Augie is correct - I'd just add that technically you do also need to account for the power factor (i.e. go from KW to KVA): I = ( P(KW)/P.F. ) / E * sq. root(3). Assuming a PF of 0.8 or so should be a safe bet since I'm guessing that you don't know the power factor. But the best way, and one I use everytime possible, is give the mfg. a call and ask the nameplate rating!
 

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
The power factor of an electric heater should be very close to unity. The major portion of the load is resistive.
 
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