load calculation

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cms78

Member
Location
san diego, ca
I need help to make a load calculation.
I have a switch gear 120v/208 Three Phase, with a 1600 amp main breaker, in a condominium complex
load:
3,branch circuit breakers 3 ph,600 A , feeding three bank of meters for dwelling units; 16 meters per bank
3, branch circuit breakers 3ph 200A ; one for equipement( elevator) ; one for exhaust fan; and one for lighting.
1, 400amp 3ph for a commercial purposes
what will be the total load? do i have room to add an extra 400amp branch circuit?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
There is not close to enough info to do a calculation. The size of the breakers has nothing to do with the calculated loads.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
There is not close to enough info to do a calculation.

Welcome to the Forum, Mr. Alwon is correct.

3,branch circuit breakers 3 ph,600 A , feeding three bank of meters for dwelling units; 16 meters per bank

If your lucky all the dwelling units are the same, do a calc for one and apply the demand factors.

3, branch circuit breakers 3ph 200A ; one for equipement( elevator) ; one for exhaust fan; and one for lighting.
That one should be easy.


1, 400amp 3ph for a commercial purposes
This one isn't so easy, does this serve more than one retail space?
 

cms78

Member
Location
san diego, ca
load calculation

The owner want to add a 400amp panel feed from the existin g switch gear 1600amp main breaker, for a bakery shop , there is room on the switch gear,but we try not to overload the main breaker 1600 amp. since there are 50 dweling units, feed from the switch gear, plus a house panel 200amp, and 200amp panel for elevator
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Semi-Retired Electrical Engineer
How many square feet? Does each unit have the ability to have its own laundry equipment? What is the rating of the central heating and cooling system? Are the ranges electric or gas? These are the questions you need to answer, in order to perform a load calculation. The process is in article 220.

Since this is an existing facility, you do have another way to discover whether there is capacity for adding the desired amount of load. If the electric utility bill has information on the peak demand each month for a year, that can be the starting point of a load calculation. Otherwise, you can place load meters at a few key locations, measure the peak value during every 15 minute interval for 30 days, and use that as the starting point. See NEC 220.87.

Welcome to the forum.
 
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