Maths check !

[studentspark]

Sorry to get you to check my maths

Adiabatic Equation.

S= Square root I2 x T / k

So if I had the figures

Ze 0.23

divide by 230v would = fault current of 1000a

Its a re-wirable switch fuse protecting the supply cable (BS3036)
so that would give a time current characteristic of 0.17 seconds

Factor of 115 (T&E cable)

So 1,000,000 x 0.17 = 170000


Square root of 170000 =412.3

Divide this by 115

3.58

So minimum size cable is 4 mm2

 

[JohnW2]

Sorry to get you to check my maths ....
So minimum size cable is 4 mm2

I haven't checked your value of 't' but your maths itself seems fine.

Kind Regards, John