Sizing circuit breaker for a non-simultaneous water heater 4.5kw, 3 phase

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Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
Hello all,

I'm confused regarding sizing circuit breaker for a non-simultaneous water heater rated for 3 phase,208V, 4.5kw. The exact model is den-40 by AO-smith. I was not able to find FLA of this water heater in their specs.
Since it is non-Simultaneous, doesn't it act as single phase? so 4.5kw/208 = 21.6 x 1.25 = 30 Amp breaker, 3 pole
If we completely size it as a 3 phase, wouldn't that be only done for a simultaneous ones only = 4.5/(1.73*208) = 12.5 * 1.25 = 20amp breaker, 3 pole

Because i looked at FLA amperage by different manufacturer. and the non-simulatinoes 3 phase water heater were being calculated as single phase, since not all heaters are turning on at same time.
Any info on this would be greatly apprecitated. Thank you!
 
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