Multi-Family Dwelling Unit Calculation

[rojhan123]

I have the following loads for a residential unit of a building. 5-Lighting Outlet, 4-Convenience Outlet, 1- Shower Water Heater @ 3000W 1-Cooking outlet, 1-Ref 1-Airconditioning Unit @ .75Hp and 1-Laundry Outlet. How will i compute for the size of the feeder for 19 units with all with the same load as stated. I will be using a 3 phase system, as per design here in the Philippines we use 110/220V system line to line. What demand factor will I apply?

 

[Smart $]

You use our (USA) National Electrical Code over there? I'd think your country would have its own electrical requirement standard, yes?

 

[rojhan123]

Yes Sir we use our own electrical code but somehow our code is actually not so far from the NEC as majority also of its provisions as based on NEC.

 

[Smart $]

Yes Sir we use our own electrical code but somehow our code is actually not so far from the NEC as majority also of its provisions as based on NEC.

Okay. But I, perhaps others that may participate, can only tell you how the load is calculated under the NEC.

General Lighting at 3VA/ft²
General use (aka convenience) receptacles included in above
2 small appliance branch circuits at 1500VA each
Laundry outlet at 1500VA

Sum above
First 3000 at 100%
3001 to 120,000 at 35%
Over 120,000 at 25%

WH at nameplate (W = VA)**
Refrigerator included in small appliance branch circuit above.
A/C unit at nameplate**
Range*



*Is the cooking outlet a range? The NEC has a demand table specifically for multiple cooking units. Also requires a particular calculation for 3Ø supplies. It is not possible to have a 110/220V 3Ø system.
**While you can't apply any demand for fixed-in-place appliances at unit level, once you have four or more such as on a multi-unit feeder and the service, you can apply a 75% demand