I can't determine CABLE SIZE & CIRCUIT BREAKER? 3

[Mah84]

Hi every body
I need your help
I have building 4th floor + roof, the high
* Height from the ground to the roof floor 21 m
* Area Floor 532 m2 each one floor
I need to calculate the consumption Amps. of air conditioning for three floors: the 2nd 3rd and 4th
Note that the owner did not identify to me any information about adjustment device
Just tell me that central air conditioning we will put it in the roof
I need to Find section area of cable, main and distribution of circuit breakers?
I Will feed this unit by independent from the rest of the other loads

thank you
Maher

 

[davidbeach]

The site is "Eng-Tips", not "Do my engineering for me."

Maybe you should check with the mechanical engineer on the project.

 

[Mah84]

Thank you Mr. Davidbeach on these tips

I am a fresh graduate and I have completed my whole in this building
The only obstacle that have passed on are feeding this air conditioning

I did not ask you to 'DO MY ENGINEERING FOR ME; I asked practical observations and tips only

 

[davidbeach]

So, somebody is designing the HVAC system; ask them. You'll get a much better answer that way than anybody here can give you. The way you frame the question suggests that you aren't in North American so I'll make up a European example. The correct answer in Oslo won't be the correct answer in Palmaro. Throw in the Mideast or North Africa and the range of answers gets even bigger. Nobody here can give you the answer, but somebody there can give you everything you need.

 

[healyx]

I agree with davidbeach, you need to ask the mechanical engineer for these loads. It is hard for us to even assist given every region will have completely different requirements.

I Australia where our peak loads are for cooling (generally speaking), a rule of thumb for planning purposes would be to allow about 70 VA/m2 for the air conditioning only load, where electrical reheat zonal or package units are used (FOR OFFICE SPACE). So for each floor, the a/c load in Australia might be about 40kVA.

As for cables and circuit breakers, this is impossible to even guess unless you tell us where you are and what standard/code you are working to.

 

[Mah84]

Thank you all
I'm actually work in Saudi Arabia and work at NEC.
I have worked before in a 70 VA/m2, and after multip. the value by number of factors, I found it very large consumption, I want other way to make sure to my work, so I will rely this method in my design thank you very much for your tips

 

[jraef]

I still think you are not getting it.

Someone is asking YOU to size the electrical load indirectly by sizing the cooling system by proxy. This is a wholly unacceptable engineering method.

FIRST the mechanical people must size the cooling system, THEN you size the electrical system once you know what it needs. Guessing based on some made up kW / m² value is not a good engineering practice no matter how old or experienced you are. You might use that to ESTIMATE the needs from a cost budgeting standpoint where you can be off by 25-50%, but that is not the way to design for construction.

"Will work for (the memory of) salami"

 

[Mah84]

I know that guessing should not be decided in the design, but what should I do, this building and the office responsible for is not their position here in Saudi Arabia but also in Jordan, the official Here are just a painter took me design the electric, but to vacate my responsibility of any fault, I'm going to put my remarks in a detail folder in the electricity department
How do you see?