25mm 120 amp 3phase question

[Spark123]

Just read what I posted, the lol wasn't aimed at your calculations, just everyone typing too fast

 

[Jim2287]

hehe,


ive done it for a Ze of around 0.35 and that allows ~35mm cable, i think im going there tomorrow so will get the true earth loops and see if all is OK

again, thanks for the help guys

 

[Jim2287]

Say if its not possible to meet the disconnection for the overcurrent , are there ways around it, like ... installing double insulated cables to prevent short circuit or earth fault ?

 

[Spark123]

RCD protection is one method, as far as I know there isn't a limit as such for disconnection time for a short circuit (L-L or L-N), just for an earth fault. However, if you are going over 5secs for a short circuit then the cable manufacturer should be consulted over the K value.
(to be pedantic the adiabatic is dealing with fault current, not overcurrent. Overcurrent protection can be provided downstream.)

 

[ricicle]

Say if its not possible to meet the disconnection for the overcurrent , are there ways around it, like ... installing double insulated cables to prevent short circuit or earth fault ?

Not really.You'd just have to use bigger cables
BTW we are not talking overcurrent, it is fault/short circuit current

 

[ricicle]

Damn you 123

 

[Jim2287]

over current due to shorts rather than load .... but you got what i meant