Copper busbar: choose the right shape to reduce cost!

One basic material used in the switchboard is the copper busbar. I currently think that no innovation has been made on the busbar design, as the majority of the use is still remaining flat copper bar.

Anyway, during the past 15 years, we have seen a strong development of different busbar section shapes (rather than just flat bars), in particular to make easier the life of the panel builder, who can now build an electrical panel or switchboard like a “Meccano”. One impact of using busbar shapes has been to reduce copper needed: the increase of the perimeter of the bubar section is giving a better heat exchange, allowing to decrease the cross section for the same busbar ampacity (current capacity), thus saving costly material ! The life of the panel builder is becoming easier with this type of busbar (special shapes also to make quick and easy connexions onto the busbar …), but I got some headaches to produce them, as due to the complexity of some shapes the tooling construction became more difficult and the lifetime of the tooling shorter.

With the high copper price, there is still a pressure on the busbar price. But as a copper busbar manufacturer I have the feeling that the panel builder may also have another look at the busbar shape and size he is using, as the cost driver for a busbar is the copper price more than the manufacturing costs : the size of busbar must be calculated very precisely to suit the need, trying to use busbar with a longer perimeter which have a better ampacity for the same cross section.

As an example, with a same cross section of 500 mm², you can increase the busbar ampacity (current capacity) by more than 20% using a 100×5 instead of 50×10!



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  • hollow Aluminium bus bar are being used for L T control panel in europe like tubular bus bars used in switchyards. Idea behind this is to reduce the weight of alum bus bar as the centre portion of bus bar is not used for current carrying and this extra weight is being elemintaed from cnetre .
    is it true ? In india this concept has not come and panel builders continue to use conventional flat bus bar in L T panle fabrication . whats going on in france on this

  • There is copper-aluminium (bimetal) busbars, witch a better choise than any shape of copper busbars.

  • I have a doubt; pls explain your point in details. if crossectional area remains the same how come the current carrying capacity will be increased……..

    • as explained in the article, the increase of the perimeter of the bubar section is giving a better heat exchange, allowing to decrease the cross section for the same busbar ampacity (current capacity), thus saving costly material !

  • please give me information how to calculate the amps ratting of busbar if cross sectional area and length is known

    • Bus Bar Ampacity:
      The NEC stipulates in the article on auxiliary gutters that a copper bus bar has a continuous ampacity of 1000 amps per square inch. Aluminum is 700 amps per square inch.
      So to calculate the ampacity of any bus bar, envision a cross section of the bar. Length is not a factor in the calculation.
      Multiply the two dimensions of the cross section as measured in inches. The product of these two numbers is the cross sectional area.
      Next multiply the area times either 1000 amps/sq inch of copper of 700 amps/sq inch if aluminum.
      This calculation is a straight square inches of the bus bar times 1000 amps/sq. inch if copper and square inches times 700 amps/sq. inch if aluminum.
      So if you have a bus bar that is 1/2 inch by 3/4 inches (regardless of length) then it is .5 times .75 equals .375 times 1000 equals 375 amps if copper and .375 times 700 equals 262.5 amps if aluminum.=)

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