does swa need additional protective conductor

[eamonn1983]

I need to work out if I will be required to run a separate protective conductor along side the swa cable I'm going to install. The cable is a sub mains feeding a 3 phase db panel in a large workshop. The cable is going to be a 50mm 4core 120 metres steel wire armoured installed in a underground duct. The protective device feeding the cable is a merlin gerin NS250N 3 phase mccb and the readings at this end are zs 0.19 and pfc 1.23KA.

I'd be grateful if someone could tell me how I can determine if this needs a separate protective conductor and if so maybe explain the calculation,to help me,in the future.

Thanks in advance

 

[Richard Burns]

This thread may help your calculations.