Optional Load Calculations

[chicago66]

Hi,
This qs. pertains to a specific condition which is required to perform Optional Calculation for Multifamily Dwelling.

As per Article 220.32 of NEC,
the multi-family dwelling I am dealing with, satisfies both conditions of not being supplied by more than one feeder & each dwelling unit is equipped with electric cooking equipment.
But each dwelling unit is supplied by electrical duct heating as opposed to electric space heating as required by the article.

Would you please let me know whether electrical duct heating would satisfy the requirement or not?
Thank you for your time...

 

[jrsummers]

Re: Optional Load Calculations

I have been looking at this same situation today. I am sizing a service for a multifamily dwelling. The following conditions apply:
(1) No dwelling unit is supplied by more than one feeder.
(2) Each dwelling unit is supplied by electric cooking equipment.

However I am having trouble interpretting the third requirement of NEC 220.32 (220.84 of the 2005 NEC). The third requirement states that each dwelling unit is equipped with either electric space heating or air conditioning, or both. My situation uses rooftop air cooled condensing units and heat pumps with supplemental electric heat to provide heating/cooling. Do I satisfy the third requirement?

 

[jrsummers]

Re: Optional Load Calculations

Sorry to piggy back on your question Chicago. I just found it interesting that I have been looking at a similar situation today.

I wish I had the answer.

 

[steve66]

Re: Optional Load Calculations

For the duct heaters: my guess would be that if they are being used as the main heat for the space, you are OK. But it wouldn't be OK if for example, you had a gas furnace, and the duct heaters were only reheating the AC air.

I also think the Rooftop units satisfy the air conditioning requirement, and the supplemental heat would satisfy the "electric space heating". so I think you are covered in either case.

Steve

 

[charlie b]

Re: Optional Load Calculations

My take is that if electrical energy is used to make the place hot, you satisfy the third requirement. Similarly, if electrical energy is used to make the place cool, you also satisfy the third requirement.