multi family load calcs

[Ken Jean]

I am embarrassed to say that after 25 years as a contractor I don't really know how to accurately do load calcs for a multi family. We have a three story, total 6700 sq ft brick building that we are converting into twelve units plus common. I need to do calculations for both with electric appliances or gas appliances. Each unit will have a combination heat/ac HVAC unit. I tried the calcs myself and came up with 485a @ 120/240v single phase for the all gas appliance type. Does this sound reasonable? Any clue for the all electric appliance calc?

Thanks in advance,
Ken

 

[bobbymari]

need some more info, avg sq footage per unit, disposals? dishwashers? laundry in units? by electric vs gas are u referring to all appliances such as electric hot water heaters, ovens, dryers ?

 

[Buck Parrish]

I am embarrassed to say that after 25 years as a contractor I don't really know how to accurately do load calcs for a multi family. We have a three story, total 6700 sq ft brick building that we are converting into twelve units plus common. I need to do calculations for both with electric appliances or gas appliances. Each unit will have a combination heat/ac HVAC unit. I tried the calcs myself and came up with 485a @ 120/240v single phase for the all gas appliance type. Does this sound reasonable? Any clue for the all electric appliance calc?

Thanks in advance,
Ken

That seems way to high

 

[dav5y]

Hope this helps. Read NEC Art. 220 first then get the electrical nameplate data from the mechanical contractor and/or owner/architect for gas and electric equipment being used. Add gen ltg load (which includes receptacle load for your use per NEC art 220.14J - contin. load) and appliance loads (combo of continuos and non. continuos loads) then I apply the Feeder demand factor from 220.84 depending on # of dwelling units (make sure you meet the conditions for using the demand factor). Thats your feeder size.

 

[Ken Jean]

Multi family load calcs

Multi family load calcs

need some more info, avg sq footage per unit, disposals? dishwashers? laundry in units? by electric vs gas are u referring to all appliances such as electric hot water heaters, ovens, dryers ?

Hi Bob,

Thanks for your help. The average unit is 550 sq ft. There will be 12 disposals and dishwashers. Laundry in units stack units and you are correct about the gas appliances.

Best regards,
Ken

 

[bobbymari]

Hi Bob,

Thanks for your help. The average unit is 550 sq ft. There will be 12 disposals and dishwashers. Laundry in units stack units and you are correct about the gas appliances.

Best regards,
Ken

Check your inbox gonna send you a sample based on most of what you provided. The program I use lists the code section next to each calculation as well as demand factors and optional method if going with heat/ac and electric appliances to walk you through it