Calculate 3phase current for breaker

[webharvest]

I have a situation with a 3phase (208V) system. The panel is total power is 41k and the panel has a 200A main breaker. To calculate the current for the breaker and make sure it meets the 80% rule is the following correct?

I(breaker) = 41k/(208*sqrt(3))= 114A

I was thinking about just using I(breaker)=41k/208 but I think the sqrt(3) comes into play because of the 3phase.

Can you confirm this and maybe give an explanation of the sqrt(3)?

 

[charlie b]

The 114 amp value is correct. In 3-phase systems, the value of the square root of three is always going to creep into the party somewhere.

Why, you ask? There is no easy answer to that question. If you took trigonometry in high school, and actually liked it, I could send you a Word file that derives three phase power using trig identities. The bottom line has the square root of three in the equation. If you want to see it, send me a Private Message with an email address.

Welcome to the forum.