Temp Load Calc

[mstrlucky74]

Came across this load calc sheet for temp. Why would you calculate everything off Kva? How would you arrive at Kva only knowing the voltage and amps of a particular load? Thanks.

 

[david luchini]

How would you arrive at Kva only knowing the voltage and amps of a particular load?

Volts * Amps / 1000 = kVA (single phase.)

Volts * Amps * 1.732 / 1000 = kVA (three phase.)

 

[iwire]

Why would you calculate everything off Kva?

It is the only practical way to total up your loads of various voltages and phases.

 

[mstrlucky74]

Thanks.

 

[mstrlucky74]

So one last think if you had a 120/208v panel what voltage would you use to calculate and why? Thanks.

 

[iwire]

So one last think if you had a 120/208v panel what voltage would you use to calculate and why? Thanks.

208, as that is the line to line voltage.

 

[mstrlucky74]

I know this is design/engineering but I’s like to know. Whatwould be the ideal way( on feed to 2 floors, etc.) and what size( MC Cable 250 or 300 I know you have VD) would you figure forthe following:


120/208V 300A bottom trough temporary panels laid out asfollows:

Floors 1-12 one on each floor

Floors 13-33 one every other floor

23-37 one every third floor

All feed from 120/208v 6000a service on ground flooralthough I think maybe using step/down xfrmr and feeding an intermediate distboard to feed the upper floor panels might be best.
Thanks

 

[Smart $]

So one last think if you had a 120/208v panel what voltage would you use to calculate and why? Thanks.

120V for 120V loads and 208V for 208V loads.

Result is sum of all loads kVA values, then divide by [208V × sqrt(3)], or [120×3], to get supply-line amperes (assumes balanced loading).