Panel scheduling and sizing

[NekoNeko]

I have 3 3 phase panels I need to set up for a project, reaching out for help is allowed, and using calculators is allowed.
I somewhat understand that on all 3 phases, I want to balance the loads across them and don't think I need too much help.

When it comes to grounding, bonding, and sizing wire sizing. I am not completely uneducated but don't know where to begin.
I have a 3-phase main panel 480Y/277V, and 2 208/120 sub-panels.


Let's say my total load across one sub-panel is 15000kVA and my total load across the main panel is 60,000kVA in a commercial setting what are some good resources to reference? Are there any Calculators that may help?

 

[Mr. Serious]

KVA to amps:

Single phase, divide by the voltage. Use the full line-to-line voltage (usually 240 volts) if loads are equally balanced on the two legs.

3-phase, assuming no imbalance, divide by the line-to-neutral voltage, then divide again by the square root of 3. You can easily remember that last one is division, not multiplication, because you know that the amps on 3-phase will be less than the equivalent amps on only a single phase of that 3-phase service, for the same number of kVA.

 

[Dennis Alwon]

3 phase use 480* 1.73 = 831 V
3 phase use 208* 1.73= 360 V

Amperage= Watts/Voltage

For bonding you eed table 250.102(C)(1)

For grounding electrode conductor use T 250.66

For equipment grounding conductor use table 250.122

 

[Mr. Serious]

I think my earlier reply has a mistake. I'm going to think about it again in the morning after I've slept.

 

[JoeStillman]

To figure out your load amps, remember 3Ø apparent power (VA) = V x A x 1.732, so A = VA / (V x 1.732). Remember to keep track of the decimal point. In your original post, you mentioned you were given a load of 60,000 kVA. I hope what you meant was 60,000 VA or 60 kVA. 60,000 kVA at 480V, 3Ø = 72,000A. If you meant 60 kVA, it's more manageable at 72 A.

 

[NekoNeko]

To figure out your load amps, remember 3Ø apparent power (VA) = V x A x 1.732, so A = VA / (V x 1.732). Remember to keep track of the decimal point. In your original post, you mentioned you were given a load of 60,000 kVA. I hope what you meant was 60,000 VA or 60 kVA. 60,000 kVA at 480V, 3Ø = 72,000A. If you meant 60 kVA, it's more manageable at 72 A.

3 phase use 480* 1.73 = 831 V
3 phase use 208* 1.73= 360 V

Amperage= Watts/Voltage

For bonding you eed table 250.102(C)(1)

For grounding electrode conductor use T 250.66

For equipment grounding conductor use table 250.122

Thanks!!