Optional Method
 

How do you determine the calculated load of a 6 Kw electric space heater unit and a 4 kW A/C using the optional method?

I thought when it was reasonable to assume that both of these units would not operate at the same time, that the lower wattage unit could be disregarded in the calculation and that the larger wattage could be used.. But the answer seems to be 4000 watts. I do not understand how they arrived at that answer. This question is from a 2005 NEC quiz.

Thank you

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