Alwayslearningelec
Senior Member
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Because you forgot the factor of sqrt(3) which comes with 3 phase power. Of course, nothing in the image says the supply is 208Y/120V 4-wire rather than 208V 2-wire, but since the result is 123A, it must be.Why am I not coming up with 123A.
You're probably correct. Even though it's not mentioned in the truncated version of the panel schedule no one is going to install a 1 phase, 208 volt panel.Because you forgot the factor of sqrt(3) which comes with 3 phase power. Of course, nothing in the image says the supply is 208Y/120V 4-wire rather than 208V 2-wire, but since the result is 123A, it must be.
Cheers, Wayne
Ah, yes, that pesky sqrt(3).What formula are you using?
44000/208/1.73=122.27 amps
With the exception of multi family dewelings feed from 120/208 three phase.You're probably correct. Even though it's not mentioned in the truncated version of the panel schedule no one is going to install a 1 phase, 208 volt panel.
Yes that is one example of where you may see a 1Ø, 208 volt panel.With the exception of multi family dewelings feed from 120/208 three phase.
Not applicable in this case.
Yep, but you are most likely to see a 120/240V 1PH3W panel fed by a 120/208V 1PH3Wfeeder.Yes that is one example of where you may see a 1Ø, 208 volt panel.
What is the 1.73 for?Because you forgot the factor of sqrt(3) which comes with 3 phase power. Of course, nothing in the image says the supply is 208Y/120V 4-wire rather than 208V 2-wire, but since the result is 123A, it must be.
Cheers, Wayne
It's because the three phases are offset by 120 instead of 180 degrees.What is the 1.73 for?
In short, anytime you use voltage in the formula you multiply the voltage by the square root of 3 or 1.73. ggunn gave you the reason.What is the 1.73 for?
There are a number of ways to think about it, but the one I like is:What is the 1.73 for?
Three phase power was pretty weird for me at first; I transitioned from semiconductors where everything is DC and data to PV where AC is a major player fifteen years ago, and commercial PV is nearly always three phase on the AC side. Here is a pretty good read to get started: https://en.wikipedia.org/wiki/Three-phase_electric_powerWhat is the 1.73 for?
You think correctly.i think three phases are offset by 120 instead of 180 degrees
I was sure but iamYou think correctly.![]()