demand calc for service

[Unregistered]

I am having trouble understanding the notes to table 220.19, electric range demand. My problem is applying the notes to choose which column and associated calc to perform.

The other question I have is in RE to demand cals for the largest motor load. Why is it taken at 25% when it seems that everywhere in 220.14 / 430.24 it says 125%?

Also confusing: If for example, the largest motor load is an applicance such as an attic fan, would I count it under the appliances section, then again in the largest motor section, or only once in the motor section?

Any clarification would be appreciated...

Thank you :)

[suemarkp]

Tell us what cooking equipment you have and we'll tell you what column to use. Do you have a single range (both oven and cookotop) or separate items. How many KW is it (or each) rated?

It is assumed that in a dwelling there will be a load diversity and you won't be having all those motors going at once. So they ding you for 25% of the largest one. However, each feeder or branch circuit needs to be upsided by 25% of the largest motor it serves for the same reason.

Appliances -vs- motors can be confusing. I don't think it really matters where you put it if you use the name plate value. After you have all of your items listed, find the largest motor in any of them and add 25% of it to your amp total. This is especially tricky with air conditioners or heat pumps. The compressor is effectively a large motor, but the MCA value on the nameplate already has the 25% factor added in so you don't have to do any more.

What gets most confusing is when you have 4 or more fastened in place appliances so you get to apply a 75% factor to those. If they are all motors, then you need to put back 25% of the nameplate value of the biggest one.

[Unregistered]

I meant for this to be in the electrical forum. Thanks for the reply though. I will repost with further in the appropriate forum...