Load Calcuulation, 6 unit apartment

[Bill Annett]

I have a 6 unit apartment building, all units will be the same, each unit has the following.
550 Square feet, 2 small appliance circuits ( 3000VA), one laundry circuit(1500 VA), one dryer (5000VA), Water Heater(4500VA), Range (8000VA) and Heat (6875VA)

I am trying to determine the Service conductor size for this building, The services disconnect will be 6 Breakers ( no main ). I used article 220.84 C and came up with a connected load of 30525 VA for each unit. I then went to table 220.84 and Multiplied 30525 VA by 6 and came up with 183150VA. I then divided it by 240 , I then multiplied that by the demand fact of .44 ( table 220.84 ) which came to 336 Amps.

Am I thinking correctly? It just seems low to me. It has no main , I can picture the tenants getting angry at the owner and turning everything on and we all know what will happen next.

I just want to be sure that my figures are code compliant. Any help will be appreciated.


Thanks, Bill Annett

 

[david luchini]

I have a 6 unit apartment building, all units will be the same, each unit has the following.
550 Square feet, 2 small appliance circuits ( 3000VA), one laundry circuit(1500 VA), one dryer (5000VA), Water Heater(4500VA), Range (8000VA) and Heat (6875VA)

I am trying to determine the Service conductor size for this building, The services disconnect will be 6 Breakers ( no main ). I used article 220.84 C and came up with a connected load of 30525 VA for each unit. I then went to table 220.84 and Multiplied 30525 VA by 6 and came up with 183150VA. I then divided it by 240 , I then multiplied that by the demand fact of .44 ( table 220.84 ) which came to 336 Amps.

Am I thinking correctly? It just seems low to me. It has no main , I can picture the tenants getting angry at the owner and turning everything on and we all know what will happen next.

I just want to be sure that my figures are code compliant. Any help will be appreciated.


Thanks, Bill Annett

Looks correct to me. I'd just ask is 8000VA the actual Nameplate data for the range?

336A would be the minimum service conductor ampacity. Nothing prevents you from making it larger.

 

[Bill Annett]

David.

Thanks for checking my math. I just wanted to be sure that it met the NEC. I can not make them increase the conductor size but I will highly recommend that they do.

Thanks Again.

Bill

 

[pjholguin]

How are you going to power common area lighting and any life safety systems? IMO...you are going to need a house panel.

I have a 6 unit apartment building, all units will be the same, each unit has the following.
550 Square feet, 2 small appliance circuits ( 3000VA), one laundry circuit(1500 VA), one dryer (5000VA), Water Heater(4500VA), Range (8000VA) and Heat (6875VA)

I am trying to determine the Service conductor size for this building, The services disconnect will be 6 Breakers ( no main ). I used article 220.84 C and came up with a connected load of 30525 VA for each unit. I then went to table 220.84 and Multiplied 30525 VA by 6 and came up with 183150VA. I then divided it by 240 , I then multiplied that by the demand fact of .44 ( table 220.84 ) which came to 336 Amps.

Am I thinking correctly? It just seems low to me. It has no main , I can picture the tenants getting angry at the owner and turning everything on and we all know what will happen next.

I just want to be sure that my figures are code compliant. Any help will be appreciated.


Thanks, Bill Annett

 

[Bill Annett]

pjholguin

To be honest. They said that the building will have only 5 Apartments and the 6th will be a house panel. I do not know what will be on the house panel so I just used the load of an apartment. This was a 6 unit apartment so I got a funny feeling that they might change it to 6 units and I just wanted to have the correct conductor size if they change it to 6 units.

We have no prints yet, I have just been going off of what I have been told.

Bill

 

[tsamples]

Looks Okay

Looks Okay

Consider that 334 amps is 55 amps per unit. At 550 sqft that seems like plenty of power. Certainly you could install a larger service, but the reasoning behind the derating is that not everyone will be running the dryer and the range while running a bath with all of the heat and lights on. This is code minimum, and likely there will never be a problem.

 

[Bill Annett]

tsamples.

Thanks for doing the math. You are probably correct, they will never use that much power. I just wanted to be sure that their installation will meet NEC standards.


Thanks again, Bill

 

[pjholguin]

That's good you have that covered...I was just offering some thoughts. Good luck!

pjholguin

To be honest. They said that the building will have only 5 Apartments and the 6th will be a house panel. I do not know what will be on the house panel so I just used the load of an apartment. This was a 6 unit apartment so I got a funny feeling that they might change it to 6 units and I just wanted to have the correct conductor size if they change it to 6 units.

We have no prints yet, I have just been going off of what I have been told.

Bill