multi family dwelling

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mhayes

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assuming a (24) dwelling unit multi family building. each dwelling unit has a connected load of about 40kw (using round numbers). after applying demand factors, the calculated load is about 20kw (again using round numbers). do I use the connected load of 40kw or the calculated load of 20kw per dwelling unit to calculate the total feeder or service load. and then can I apply the demand factor shown in table 220.84.

Thanks, mike h.
 
I think I disagree. I put it that way, because I am neither sure of the question nor sure of the previous reply. So I'll start from scratch.

When you wish to size the feeder to an individual unit, you calculate the loads on that unit alone. You apply any demand factors that are available, taking into account only the items in that unit.

When you wish to size the service conductors, you calculate all the loads that will be passing through those wires. You add all the loads on all the units, and then start applying the demand factors. In your example, you do not take 24 times the 20KW (i.e., the value that has had the individual unit's demand factors applied). Rather, you take 24 times the 40KW, and apply demand factors to that result.
 
You can allways o out and get a good software program for a few hundred that will do all that for you and generate a schedule for the prints

Ken technogeek
Always looking for the fastest but best way (time is money) why do by hand for severial hours when a software program will do it in a few seconds/minutes
 
A software program can give you an answer in seconds, but not until you spend minutes or hours finding out the information you need to give the program, before it can begin to do its job. If you and I are given the same input information, and you begin loading it into a program at the same time I begin scrawling notes on a piece of paper, you will probably get the corect answer first. But my answer will also be correct, and I won't be more than a minute or two behind you.
 
True, but with the new MEP09 loads are calcuated as items are inserted all the way back. By putting items with different load catagories for the same item as you insert them into AutoCAD MEP the schedules are automaticly updated as each item is inserted. With custom spreadsheets and two way comm between autocad and excel now most all loads are instantly calcuated with all demand factors as you have selected. Also a warning pops up when I reach a preset VA value warning me that I am about to overload a circuit.

Bout time Autodesk.

And with Acad Electric I can track wire numbers automaticly project wide. My current project has over 100,000 wires. Everything from 120V control to 4160V motors.
 
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