Busbar sizing

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Electriman

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Good morning,

I am working on a project that I would need to size a copper busbar for 5000A 500 VDC. I could not find anything in NEC that talks about busbar ampacity. Does anyone know what size copper busbar would fit the job? If you have any short guide of how to size the busbar I would appreciate it. I also appreciate it if anyone knows of any busbar vendor that I can go to for purchasing.

Thanks
 
From the NYC Electrical code amendments manufacturer's use these parameters:
408.60(E) Busbars.
(1) General. Busbars shall be sized based on 1000 amperes per square inch for copper and 750 amperes per square inch for aluminum.
Exception: In service switchboards, generator paralleling switchboards and when connecting to devices rated over 2500 amperes. See 408.60(E)(2) and (E)(3) below.
(2) In Service Equipment And Switchboards Supplied Directly From Separately Derived Systems. Line-side busbars in service switchboards and all busbars in generator paralleling switchboards shall be considered service conductors and shall comply with the requirements of 230.42(A).
(3) Connection to Devices Rated over 2500 Amperes. Busbars shall be sized in accordance with (a) and (b) below when connected to a device (switch or circuit breaker) over 2500 amperes:
(a) Over 2500 amperes but less than 5000 amperes, busbars shall be sized based on 800 amperes per square inch for copper and 600 amperes per square inch for aluminum.
(b) 5000 amperes and over, busbars shall be sized based on 700 amperes per square inch for copper and 525 amperes per square inch for aluminum.
Click to expand...
 
You will need to consider the configuration of your paralleled conductors. Busbars are typically spaced 1/4" apart, but greater spacing may provide better heat transfer, and reduce the proximity effect, with higher ampacities. The bus orientation also affects the ampacity, side by side has lower ampacities than when the bars are stocked above each other.


One reference I found shows (3) 1/2" x 8" with 1/4" spacing would handle 5,220A, while (2) 1/2" X 8" with 2-3/8" spa ing would be 5,023A.
 
jim dungar said:
You will need to consider the configuration of your paralleled conductors. Busbars are typically spaced 1/4" apart, but greater spacing may provide better heat transfer, and reduce the proximity effect, with higher ampacities. The bus orientation also affects the ampacity, side by side has lower ampacities than when the bars are stocked above each other.


One reference I found shows (3) 1/2" x 8" with 1/4" spacing would handle 5,220A, while (2) 1/2" X 8" with 2-3/8" spa ing would be 5,023A.
Click to expand...
Thanks. I would appreciate if you could share that for me.
Also, any recommendation for busbar manufacturers?
 
My reference was from a 1958 publication and was for AC applications.

You might want to sketch out your possible configuration/layouts first then see if you can find material that fits.

Have you gone to sites like this one?

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.
www.copper.org www.copper.org
 
Electriman said:
Good morning,

I am working on a project that I would need to size a copper busbar for 5000A 500 VDC. I could not find anything in NEC that talks about busbar ampacity. Does anyone know what size copper busbar would fit the job? If you have any short guide of how to size the busbar I would appreciate it. I also appreciate it if anyone knows of any busbar vendor that I can go to for purchasing.

Thanks
Click to expand...
A 4" wide by 0.25" thick copper buss bar is good for 1000 amps . Did a electroplating install years ago for 6000 amps DC at 12 to 24 volts. Install 6 of these 4" wide copper buss bars to first station then reduced it from there. Extra fun drilling copper buss bars all day. Owner purchased a cheap drill press and burnt out the thing in a day. Finially purchased the correct drill bits along with proper cooling fluid. Drilled 7/16" holes and used 3/8" grade 5 bolts to join them.
 
Something I would like to recommend, that I became aware of on this forum from other posters.

Do a search on Electromotive Force in switchgear, and Electrodynamic Force, and Electromagnetic Force.
I have assembled switchgear several times, and bus duct, but had not previously been introduced to this.
It is, IMHO, eye opening to the design of bus plates, and the necessary support of the plates, to prevent faults from happening, or preventing an even worse situation from happening.

My apologies if you are already learned in this. If not, it is worth looking at, even just for added knowledge.
 
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