AC load included with 220 Part III Standard Calculations

LibertyEngineering

Senior Member
Location
Allentown, PA
Odd thing about Part III calculations is it does not get very specific about including air conditioning loads in your calculation, 220.50 Motors which includes hermetic refrigerant motor compressors is the only way to pick up on that and you also need to know what a hermetic refrigerant compressor is, AKA your outdoor unit on a typical residential AC split system. If you are passing thru the code doing the standard calcs one might simply pass 220.50 since the header is Motors and if you've no other motors in the home to consider you may not read the section.
The other odd thing about the Part III calcs is there is no indication of using the larger of the 2 loads, heat load or AC load, or anything to distinguish the use of a heat pump with back up electric resistance heat. The calc has you include both space heating (220.51) load and AC load. All items which are clearly covered in the Part IV optional calculations as part of 220.82 (C)
 

xptpcrewx

Power System Engineer
Location
Las Vegas, Nevada, USA
Occupation
Licensed Electrical Engineer, Licensed Electrical Contractor, Certified Master Electrician
Odd thing about Part III calculations is it does not get very specific about including air conditioning loads in your calculation, 220.50 Motors which includes hermetic refrigerant motor compressors is the only way to pick up on that and you also need to know what a hermetic refrigerant compressor is, AKA your outdoor unit on a typical residential AC split system. If you are passing thru the code doing the standard calcs one might simply pass 220.50 since the header is Motors and if you've no other motors in the home to consider you may not read the section.
The other odd thing about the Part III calcs is there is no indication of using the larger of the 2 loads, heat load or AC load, or anything to distinguish the use of a heat pump with back up electric resistance heat. The calc has you include both space heating (220.51) load and AC load. All items which are clearly covered in the Part IV optional calculations as part of 220.82 (C)
Lots of odd things in Article 220 in need of an overhaul imo.
 
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