calculate over current protection csa

[beaver74]

hi all have a 32A 3036 circuit which feeds a 45A DP isolator from there 3 radiale circuit wired in 1.5mm with fuse spur providing upstream over current protection

now can any one remind me how to calculate short circuit current to be sure cable will be protected due to a short feed side of the fuse spur

cheers in advance

 

[Silly Sausage]

Save yourself the mental effort & rip it all out & start again.

 

[Guest123]

Are you thinking adiabatic here???

PEFC can be calculated using the formula Uo/Zs

 

[beaver74]

Hi Lenny

yes I am thinking adiabatic I know each circuit is protected against over current up stream but as the OCP is a 3036 I want to check cable will take a short and safely clears the 32A3036
Archy there is no chance of riping it out but if need be some alterations at the supply end

 

[Guest123]

What size cable runs from the CU to the isolator???

 

[Deleted member 26818]

The easiest way would be to measure PSCC at the points of utilisation, and then apply the adiabatic equation.

 

[needasparks]

are you looking at the 3036 (32A you sure?) covering the the supply cable (6mm ?) or the 1362 in the spurs covering the 1.5/1.0mm.
assuming T&E thermal constraints.

 

[Risteard]

30A BS 3036 surely? Can't be 32A.

 

[beaver74]

sorry yes 30A3036 the cable feeding the 45A DP switch is a bit of 6.00