I have 2 questions about Dwelling unit calculations

[jllapitan]

1) in a dwelling unit calc, there is a demand for 4 or more fixed appliances, I am having trouble identifying for my students exactly what this is. Now I understand normal appliances but I have been getting questions as to what these appliances are??? yes DW or disposals, ect but is a hot tub a fixed appliance? sauna, sump pump?...I know the definition but see no clear answer?
2) when the calculation (standard) asks for 25% of the largest motor, again I am having difficulty answering exactly what is being called a motor. Is air conditioner a motor we need to visit? freezer? Hot tub? or is it anything what so ever that is motor driven? I appreciate your input, again I am just having difficulty identifying exactly what or which motor should be used ....thank you for the response jllapitan Instructor

 

[charlie b]

I would include a sump pump in the demand factor. But I don't see a hot tub or a sauna as performing a function, at least not in the same sense that a dish washer performs a function. But there is room for disagreement on that point. For my part, I seldom get to use that particular demand factor (from 220.53) unless I am designing a multi-family dwelling unit. That way, I get to count the DWs in all 72 units (or whatever), when I calculate the service size. A single dwelling unit will seldom have four or more fixed-in-place appliances.

For a single family dwelling unit, the largest motor is most likely involved in air conditioning. If the house is in my area of the country, it is unlikely to have air conditioning, and the largest motor would be either the sump pump (which I don't have) or the dish washer (for which the motor is so small as to not influence the load calculation in any significant way). Absent any other choices, however, and if pushed by the AHJ to include the 25%, I would give him the DW motor.

Welcome to the forum.