Sizing a generator

[fisherelectric]

Don't know how to size a generator. Added up all loads that are wanted including 2 ref, floor heat, hwh, well pump, wine room cooler, mw oven, etc added in 2500 watts for lighting, TVs, computer for total of 19.56 KW. On top of this want to add a heat pump with 96 LRA, 27.6 RLA. Question is: I was told to use .67 as an intermittant use factor. Is this true and how do I factor in the heat pump? Do I have to factor in starting current of wine cooler unit (12 amps)? The generator I would like to use is a 20KW Generac with a "surge capability" of 146 amps. Thanks in advance for any advice.

 

[ceb58]

Don't know how to size a generator. Added up all loads that are wanted including 2 ref, floor heat, hwh, well pump, wine room cooler, mw oven, etc added in 2500 watts for lighting, TVs, computer for total of 19.56 KW. On top of this want to add a heat pump with 96 LRA, 27.6 RLA. Question is: I was told to use .67 as an intermittant use factor. Is this true and how do I factor in the heat pump? Do I have to factor in starting current of wine cooler unit (12 amps)? The generator I would like to use is a 20KW Generac with a "surge capability" of 146 amps. Thanks in advance for any advice.

Never make it with a 20 kw. The load must be calculated per Art.220 by 702.4 (B) (2) 2011
There are several loads on the list that are just dumb. Wine cooler, floor heat, come on you are in an outage situation. Run the needed loads and survive or don't complain about price when it come up to a 30 or 35 kw unit.

 

[bphgravity]

It appears you are refering to an "optional standy-by system". Therefore, the sizing & capacity requirements would be identified in Section 702.5 of the NEC. The use of an automatic transfer switch versus a manual transfer switch will significantly impact the sie generator that will be required or total load that can be supplied.

I amn ot familair with any code permitted "factoring" other than as permitted in Article 220 of the NEC...