3 phase Delta Souce with Single Phase Load

[Dodgeviper1017]

On complex imaginaries video on sqrt of 3. They solver for power with a delta source and a single phase load. Valies given Iphase = 25 A and V line to line = 480 V what is the Power? So I though of 2 ways to do this 1 is to convert phase current to line current and multiply. The seconf is to just multiply phase current by phase voltage because phase voltage = linr to line voltage. They converted to line current to solve it which is fine I get it but why not the other way. To my point in another video with 3 phase delta source and 3 phase Y load. They give Vphase = 2.77 kV and I line = 45 A. These are both load values and we need to find power at load. I assumed that Iline = Iphase and Vphase = 2.77/sqrt (3) then to get power P = 3VI or V line to line×I line x sqrt (3) which gave me the same answer. What im confused on is how come it was ok to assume I line = I phase and not convert to line here but not  other way around before?

 

[Dodgeviper1017]

For now im just gonna assume if I am given Delta and phase current and Line voltage to convert phase current. However if it is wye I can assume I phase = I line and V line is fine to use.

 

[Dodgeviper1017]

I guess I should convert V line to phase actually to ensure they are the same type of value.