Panel rating
#1
07-21-03, 11:01 AM
Panel rating
Hi all,
I have a question about the panel size. If a panel have 200 A, and 42 poles, say each pole is 15 or 20 amp breakers? Wouldn't it be overload if all those 42 pole activate (running) at the sametime? I know it's wrong to add 42 poles and multiply by 20 A each. But I can't find a logical explaination for this question. Please give me some advice, and thank you very much in advance.
Tuan
I have a question about the panel size. If a panel have 200 A, and 42 poles, say each pole is 15 or 20 amp breakers? Wouldn't it be overload if all those 42 pole activate (running) at the sametime? I know it's wrong to add 42 poles and multiply by 20 A each. But I can't find a logical explaination for this question. Please give me some advice, and thank you very much in advance.
Tuan
#2
07-21-03, 11:36 AM
Member
Join Date: Dec 2001
Location: New York
Posts: 1,287
Upvotes: 0
Received 0 Upvotes
on
0 Posts
The calculation/gamble is that you will never load each pole to its maximum amount, and that through diversity, you will never use all the loads at the same time.
#3
07-21-03, 11:41 AM
Member
Join Date: Feb 2003
Location: Indiana
Posts: 317
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Besides it is 200a per phase and there are two phases. 1/2 of the panel being one phase and 1/2 the panel the other phase.
#4
07-21-03, 03:20 PM
The basis for a design is the connected load. If you must design for 42 motors, each in contant operation and each with a full-load current of 20 amps, then the Code articles on feeders and branch-circuits which supply motors-loads is refered to.
The Code has specific Articles that apply to "dwelling-units". A "dwelling-unit" could be a 4,000 sq.-ft. house or a 600 sq.-ft. apartment. What's important in such Code calculations is the concept of "Demand-Factor", the Factors based on rigorous analysis of electrical loads. If you have 40 apartments each with a 12 kw electric range ,you calculate the maximum load by applying the Demand-Factor based on the number of ranges instead of simply multiplying 40 X 12kw = 480 kw.
The Code has specific Articles that apply to "dwelling-units". A "dwelling-unit" could be a 4,000 sq.-ft. house or a 600 sq.-ft. apartment. What's important in such Code calculations is the concept of "Demand-Factor", the Factors based on rigorous analysis of electrical loads. If you have 40 apartments each with a 12 kw electric range ,you calculate the maximum load by applying the Demand-Factor based on the number of ranges instead of simply multiplying 40 X 12kw = 480 kw.
#5
07-22-03, 10:15 AM
Thank you all for replying my question. Another thing regard to the total Amp for the panel is that "Continuous Load". CL is a load that constanly work for 3 or more hours. Is it just apply for Lighting only or every device in the house that work for more than 3 hours such as Computer, Stove, ...
Thank you all,
Tuan
Thank you all,
Tuan
