why calculate with 230 rather than 240?

[LukeScotty]

Correct me if i am wrong but do we do calculations with 230 instead of 240 because of voltage drop, if your allowed 4% then 4% of 240 is 9.6v. 9.6 - 240 is 230.4 which is more or less 230V

I don't know whether I'm right or wrong, please comment

regards luke

 

[TonyM58]

Luke, basically no!

We have standardised at a Uo of 230V, instead of the previous 240V (I beleieve as part of CENELEC, harmonisation etc)

You work put the 4% of the Uo, so for 230 is 9.2V. I quite often use this in reverse in the v drop calcs, by putting 9.2 in as the answer and seeing how far i can go with a cable of set mV/A/M for a set design current

In the 17th, the V drop changes, aint got the details but there are different percentage values depending on your circuit.