Apartment Building House Loads Demand

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MyCleveland said:
Hot water….does the building panel POWER an electric hot water tank in each unit ?

Your total AFTER using table 220.84 is higher ?
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Sorry I’m wrong, actually there is no electric hot water heaters, it’s gas.

also yea after using 220.84 and multiplying by .23, it’s higher…

How I calculated the net total demand of the entire apartments:

1. Added all the square footages and multiplied by 3. Added total small appliance and total laundry circuits from all the apartments then used table 220.42.

2. added all the AC units of all apartments

3. added all the appliance circuits fastened in place and multiplied total load by 75%

4. added up all the power of clothes dryers of all the apartments and used 220.54

I then added all the loads in steps 1,2,3,4 to get the answer.

optional method:

1. I added all the apartment demand VA calculated in part 3 from the NEC and then added 8kw for range to each apartment and then I multiplied total VA by .23
 
Tainted said:
Is the way I did it correct?
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Can't say....did you add in loads from 220.52 A & B ?

If you have done this before, you will know.
If not, try looking through some examples in annex D.
They have some apartment building examples I believe.

With the limited reduction factors in part 3 as compared to 220.84 is the cause of my concern.
This article is letting you reduce the total load by over 75%, and your penalty for adding in 140 nonexistent ovens is only around 260kVA.
 
MyCleveland said:
Can't say....did you add in loads from 220.52 A & B ?

If you have done this before, you will know.
If not, try looking through some examples in annex D.
They have some apartment building examples I believe.

With the limited reduction factors in part 3 as compared to 220.84 is the cause of my concern.
This article is letting you reduce the total load by over 75%, and your penalty for adding in 140 nonexistent ovens is only around 260kVA.
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I redid my calcs and I actually did get 500A smaller.

also, I still don’t understand what to do with motors for house loads, should I just add all the motors FLA? But they are not continuous…

i referred to 220.50 but I’m still not getting it.

i have:
(3) 10Hp pumps
(1) 2Hp pumps
(3) 3/4Hp pumps
(4) 25Hp elevator motors
 
Glad you worked through it…

House loads get NO discount or access to table 220.84.
Look back at post 11, 430.24…
125% of largest mtr + all remaining.
Use fla numbers for a given HP size from table in back of 430.
Elevator(s), I would use the larger fla of 430 table vs data sheet from elevator vendor.
 
MyCleveland said:
Glad you worked through it…

House loads get NO discount or access to table 220.84.
Look back at post 11, 430.24…
125% of largest mtr + all remaining.
Use fla numbers for a given HP size from table in back of 430.
Elevator(s), I would use the larger fla of 430 table vs data sheet from elevator vendor.
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But this makes no sense, not all of the motors are going to be on at the same time so why do I have to do 125% of the largest and then sum up all the other motors?
 
Yes, if you are sure these loads are non-coincidental, then go with your worst or highest value. I would still list them in my dwg load calc and state why you have not added them to your total. Keep in mind YOU do not decide which loads to remove, only the designer of that system….and get this in writing.
 
MyCleveland said:
Yes, if you are sure these loads are non-coincidental, then go with your worst or highest value. I would still list them in my dwg load calc and state why you have not added them to your total. Keep in mind YOU do not decide which loads to remove, only the designer of that system….and get this in writing.
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Ok, what I mean by “not all are going to be on at the same time” is that there is an extremely low chance that all motors are going to be on at once. Non of these motors are continuous… and some at some point in time will be on at the same time and some will not, it depends on the timing. Could I still apply the non-coincidental load?
 
Tainted said:
Ok, what I mean by “not all are going to be on at the same time” is that there is an extremely low chance that all motors are going to be on at once. Non of these motors are continuous… and some at some point in time will be on at the same time and some will not, it depends on the timing. Could I still apply the non-coincidental load?
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You are speculating…unless you designed and understand how all these systems work. Will a few motors really impact whether your service is say 3000amps or jumps to 3500amps.
 
MyCleveland said:
You are speculating…unless you designed and understand how all these systems work. Will a few motors really impact whether your service is say 3000amps or jumps to 3500amps.
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I have (4) elevator motors… each 25HP, that a huuuge amount of load… so yea it does impact
 
MyCleveland said:
Are you telling me these 4 elevators will never run at the same time ?
They will, short time intervals, but they will run.

So where are you at with total service size ?
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720000VA at 2000A for all 125 units (it’s actually 125 and not 140). House loads is 270000VA at 750A

so total service size is 2750A, does that seem oversized?

And I know that all the elevators have potential to be on at the same time, but I mean what about other motors? How will I know for other motors?
 
Tainted said:
720000VA at 2000A for all 125 units (it’s actually 125 and not 140). House loads is 270000VA at 750A

so total service size is 2750A, does that seem oversized?

And I know that all the elevators have potential to be on at the same time, but I mean what about other motors? How will I know for other motors?
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2750 seems light, but be confident in your calcs.

Go back to post 31…unless someone can put in writing the loads are non-coincidental, call in done and move on.

Now work out your utility service options, single vs dual mains, sub feeders to your meter stacks and call it done.
Remember to tally EACH meter stack using 220.84…difference being a smaller reduction dependent on number of units each stack serves.
 
MyCleveland said:
2750 seems light, but be confident in your calcs.

Go back to post 31…unless someone can put in writing the loads are non-coincidental, call in done and move on.

Now work out your utility service options, single vs dual mains, sub feeders to your meter stacks and call it done.
Remember to tally EACH meter stack using 220.84…difference being a smaller reduction dependent on number of units each stack serves.
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Too light? hmmm... what are you comparing it to? What do you think the amps should be? If I got 2750Amps, I'm probably gonna spec out for a 3000A switchboard with a 3000A main fuse. All the individual apartment OCPD are gonna be 100-125Amps.

Also what do you mean by tally each meter stack using 220.84?
 
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Tainted said:
Too light? hmmm... what are you comparing it to? What do you think the amps should be? If I got 2750Amps, I'm probably gonna spec out for a 3000A switchgear with a 3000A main fuse. All the individual apartment OCPD are gonna be 100-125Amps.

Also what do you mean by tally each meter stack using 220.84?
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Light…just an observation. I said to be confident in your calcs.

You stated threads ago you were going with utility metering for each unit in the basement. I assume you have verified with utility that they are going to be providing and reading 126 meters at this address.

What type of distribution equipment are you planning for all these meters ?
 
MyCleveland said:
Light…just an observation. I said to be confident in your calcs.

You stated threads ago you were going with utility metering for each unit in the basement. I assume you have verified with utility that they are going to be providing and reading 126 meters at this address.

What type of distribution equipment are you planning for all these meters ?
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I haven’t talked or sent any requests to coned yet, i’m doing demand load calculations to send load letter to coned and what we are proposing. I will be using Eaton coned approved meter stacks. each meter bank will have a terminal block and will be powered by the switchboard.
 
So these meter stacks each have a feeder originating from main board.

Comment was in sizing these feeders you want to gain access to table 220.84.
So you will calc each feeder like you did the overall apartment load using 220.84.
 
MyCleveland said:
So these meter stacks each have a feeder originating from main board.

Comment was in sizing these feeders you want to gain access to table 220.84.
So you will calc each feeder like you did the overall apartment load using 220.84.
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Got it! Thank you for your help! I guess it’s up to me to figure out if the 2750A seems correct for the overall house + apartment loads… wish i seen example of demand loads regarding house loads but there isn’t really any out there, only. for dwelling units
 
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