Load Calc for 208V Multifamily unit?

[jahilliard]

I am required to provide a Load Calculation for a remodel. The service for the unit is 208V(Phase to Phase) "single phase" that originates from a 120/208V Y System. Would I calculate the total Amperage by simply using I = P/E or do I need to include figure 1.73 into the equation to get an accurate number?

 

[charlie b]

1. Multiply the current associated with 120 volt, single phase loads by 120.
2. Multiply the current associated with 208 volt, single phase loads by 208.
   
3. Add the two results.
4. Divide by 208.
5. ​That is the total current on the service.

The value of the square root of 3 (i.e., 1.732, or thereabouts) only comes into play when you deal with all three phases.

 

[Jim_SWFL]

Yep - sum up your 120v and 208v loads in VA, divide this by 208 to get amperage.

Beyond summing your loads, there are demand factors that can be applied as permitted by Art 220.

 

[kwired]

The value of the square root of 3 (i.e., 1.732, or thereabouts) only comes into play when you deal with all three phases.

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