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Direct Buried cables within a controlled area and what constitutes mechanical protection

Former Community Member
Former Community Member
Hello 


I have a  query raised by a client stating that a PV solar Generation site built on agricultural land is non compliant due to direct buried cables. 

Some of the DC string cable is direct buried roughly at 600 depth laid within  cable sand and protection tape over. 

The cable spec is EU and states is suitable for direct burial. 

The protection system constantly monitors the  insulation resistance and dis engages the inverter upon fault. 

The client has stated a non compliance due that no mechanical protection has been installed underground but all cables above ground are mechanically protected. 

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  • 0
    PV d.c. side can be interesting. Usually fault currents of themselves aren't too much of a worry since the supply is limited by what the panels can produce - sizing the cables to (from memory) 125% of the panel's maximum nominal current usually provides all the fault protection the conductors need.


    If the inverter disconnecting from the d.c. side also means that the d.c. side is isolated from earth, then you might have shock protection (by means of a separated system) even in the case of a cable being spiked and the d.c. cables still "live". But that of course depends on the d.c. side not being deliberately earthed before the inverter and how well you can reliably insulate it from Earth in general (much harder with larger systems).


       - Andy.
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  • 0
    PV d.c. side can be interesting. Usually fault currents of themselves aren't too much of a worry since the supply is limited by what the panels can produce - sizing the cables to (from memory) 125% of the panel's maximum nominal current usually provides all the fault protection the conductors need.


    If the inverter disconnecting from the d.c. side also means that the d.c. side is isolated from earth, then you might have shock protection (by means of a separated system) even in the case of a cable being spiked and the d.c. cables still "live". But that of course depends on the d.c. side not being deliberately earthed before the inverter and how well you can reliably insulate it from Earth in general (much harder with larger systems).


       - Andy.
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