Diversity

[eeee]

I have been told by the contractor several times now that diversity has been added in to his power panel schedule. I know that I will compare an entry in the main distribution schedule with the final sum for demand loads in the subpanel and the figures do not match. I.E. the subpanel total for demand load does not equal the entry found for that subpanel in the main distribution panel schedule, but sometimes it does.

The contractor says because he added diversity in to his schedule. What is diversity??

 

[bob]

Re: Diversity

eeee
I think he means demand factor. Read the definition in article 100.

 

[charlie b]

Re: Diversity

"Diversity" is a technical term that means, roughly, "I don't know what I am talking about so I'll use a technical term that sounds reasonable, and I hope that nobody will question me further."

There is a real danger in using spreadsheets as the means of performing load calculations for services and feeders. The problem is in the method of accounting for what Bob correctly called "demand factors." Suppose for example that you are calculating a feeder to a sub-panel. Suppose the spreadsheet applies the demand factor of 220.42 to reduce the total lighting load for that feeder. Now suppose the spreadsheet adds up all the loads for that sub-panel, and inserts the resulting total load into the panel schedule for the main service panel. Finally, suppose that the main panel's spreadsheet looks at all lighting loads, and applies the demand factor of 220.42. This will create an error, in that it applies demand factors twice for the same load. To get the correct result, the panel schedule for the main panel has to have the total of all lighting loads from all sub-panels without having any demand factors yet applied, so that it can apply a demand factor one time for the entire service.

I can't address your contractor's panel schedules without seeing them. If they were done in a spreadsheet, then I would have to see the spreadsheet electronic file. I would need to review every cell in which a mathematical manipulation was performed, to see how they were using the formulas. But in general, the total load that shows up at the bottom of any one sub-panel's schedule should match the load that shows up for that sub-panel in the schedule for the next panel upstream.