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Radial Voltage Drop Calculation?... By Load or MCB Rating?

Nano Brewery
I'm doing the calculation for total voltage drop.  I have 14 radials/ways going out.  As I understand it, that would equal a max allowance of 0.285% voltage drop per radial/way.  Or some sort of mixture throughout not exceeding the 4% drop allowance overall.  Firstly, is this correct? 


Secondly, should I be doing my calculations based on actual Load or the MCB ratings of the individual radials/ways? 


Thanks in advance!
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    Yes, that is correct. Don't go overboard either, a 5.1% worst case drop is not a disaster! In fact, all of the loads you have are not particularly sensitive, LED lights of the "not dimmable" type don't usually flicker, and the rest are non-critical. The effect of voltage drop to motors is reduced starting torque, and possibly increased current consumption for fixed loads. It might just cost you a little more money for the electricity, or more money for cables if you reduce the drop to a low level. The choice is part of the design process.


    David CEng.
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  • 0
    Yes, that is correct. Don't go overboard either, a 5.1% worst case drop is not a disaster! In fact, all of the loads you have are not particularly sensitive, LED lights of the "not dimmable" type don't usually flicker, and the rest are non-critical. The effect of voltage drop to motors is reduced starting torque, and possibly increased current consumption for fixed loads. It might just cost you a little more money for the electricity, or more money for cables if you reduce the drop to a low level. The choice is part of the design process.


    David CEng.
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