Calculate load requirements for a generator

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mikepeters

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I have a friend in Papua New Guinea that needs help calculating the load requirements for a generator for a three story Appartment/Classroom/office building. The building is 1568 sq ft each floor. The power available is 3 phase, 4wire, 240/415v (240v to ground). This is the Australian electrical system and we do not have a code book.

top floor-contains 2 appartments
middle floor-contains 6 offices, and 1 large classroom
ground floor-contains 2 restrooms,1 laundry room, 6 dorms, and 1 kitchen.

Equipment loads:
6 a/c units @ 3200 watts each (1 for ea office).
2 a/c units @ 6,000 watts each (1 for ea apt.).
3 (non-industrial) refrigerators.
2 washing machines.
4 water circulating pumps (1/4 horsepower?)
3 possible microwaves
25 ceiling fans
all lighting will be fluorscent, no incandescent
1 existing building with an 80 amp main breaker

0 electric clothes dryer
0 electric range
0 electric water heaters
0 electric heat

Need to Know:
1) The total connected load service requirements for the building (What will the main breaker size be?).
2) What is the minimal size generato for this load?
3) Seperate sizing of the generator is there are no a/c loads while generator is being used for emergency backup.
4) is there any way to get an Australian Code book or an international code book?

[ January 16, 2006, 11:38 PM: Message edited by: mikepeters ]
 
Re: Calculate load requirements for a generator

what do you mean by "1 existing building with an 80 amp main breaker"? Is the whole thing on an 80 amp main now, or is there an 80 amp feeder to another building?
 
Re: Calculate load requirements for a generator

I meant that there is an 80 amp feeder to another building that will also be powered up by the new service. I'm sorry about the miss communication.

[ January 17, 2006, 05:13 AM: Message edited by: mikepeters ]
 
Re: Calculate load requirements for a generator

You make it sound like this is an existing building.

If so, can your friend get an average demand from the power company?
This would be one way to do it.

There is still not quite enough info to give you a more accurate answer.
You could also go to the generator manufacturers web site and see if they have an on-line calculator.

You could buy the NEC from this site, but I don't know if that would help.

Have you tried an on-line search for an Australian Electrical Code?
 
Re: Calculate load requirements for a generator

The air conditioners are going to be dominate items. For service feed, you have to think when there is a power failure and when it comes back on all 8 air conditioner are likely to jump on line at the same time.

For generator, the start surge on 6KW air conditions can be in order of 150+ Amps each.
 
Re: Calculate load requirements for a generator

Mike, contact some Generator manufacturers, they can help you size this. There are a number of factors including (but not all inclusive) load, altitude, fuel source(s), etc...

Roger
 
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