I'm doing an 80 unit apartment building. I have 3 meter stacks on 3 different floors (2nd, 3rd, and 4th of a 4 floor building) due to space limitations (had no space to put all the meters together).
Anyway I have done my calculations for the 3 separate meter stacks and used the demand factors in table 230.32. I came up with the following loads:
Meter Stack 1 = 1069 A w/30 units
Meter Stack 2 = 1079 A w/30 units
Meter Stack 3 = 857 A w/20 units
total = 3004 A
I want to use a switchboard on the first floor w/3 breakers in it to serve the three meter stacks (the house loads will be on another service lateral).
Do I add the total of these three meter stack loads to get the bus rating of the switchboard? Or can I use a the total load of the three meters stacks (before applying any demand from table 230.32) and apply a greater demand factor (80 units total instead of the separate calculations with the 30, 30, and 20 units)?
I will try to make this a little more clear:
If I add the the three meter stacks with the 220.32 demands applied I have 3004A and I would need a 3500A bus.
Now, if I took the totals before applying any 220.32 demand factors on the separate meter stacks I would have:
8763.88 A total with 80 units I would apply a 23% demand factor based on 220.32. The total load would then be 2016 A.
So the bus would only have to be rated to handle the 2016 A or a 2500 A bus.
Now heres my problem with doing it this way:
Meter Stack 1 = 1069 A and would need a 1200A breaker on the switchboard
Meter Stack 2 = 1079 A and would need a 1200A breaker on the switchboard
Meter Stack 3 = 857 A and would need a 1000A breaker on the switchboard
Now a 2500A bus switchboard has breakers totaling 3400A. Is this acceptable?
Also, would this arrangement be considered 3 mains? or 3 branch devices?
Anyway I have done my calculations for the 3 separate meter stacks and used the demand factors in table 230.32. I came up with the following loads:
Meter Stack 1 = 1069 A w/30 units
Meter Stack 2 = 1079 A w/30 units
Meter Stack 3 = 857 A w/20 units
total = 3004 A
I want to use a switchboard on the first floor w/3 breakers in it to serve the three meter stacks (the house loads will be on another service lateral).
Do I add the total of these three meter stack loads to get the bus rating of the switchboard? Or can I use a the total load of the three meters stacks (before applying any demand from table 230.32) and apply a greater demand factor (80 units total instead of the separate calculations with the 30, 30, and 20 units)?
I will try to make this a little more clear:
If I add the the three meter stacks with the 220.32 demands applied I have 3004A and I would need a 3500A bus.
Now, if I took the totals before applying any 220.32 demand factors on the separate meter stacks I would have:
8763.88 A total with 80 units I would apply a 23% demand factor based on 220.32. The total load would then be 2016 A.
So the bus would only have to be rated to handle the 2016 A or a 2500 A bus.
Now heres my problem with doing it this way:
Meter Stack 1 = 1069 A and would need a 1200A breaker on the switchboard
Meter Stack 2 = 1079 A and would need a 1200A breaker on the switchboard
Meter Stack 3 = 857 A and would need a 1000A breaker on the switchboard
Now a 2500A bus switchboard has breakers totaling 3400A. Is this acceptable?
Also, would this arrangement be considered 3 mains? or 3 branch devices?
