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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
    Is it supposed to meet BS7671 ?  Or are there the equivalent of makers instructions that over-rule it ?

    In practice it may be more pertinent to ask are the cable routes out of the way and are they  well marked/ recorded  or are they likely to be ploughed up?

    Given the insulation monitor and ADS, assuming the cable has a jacket that will survive burial, I'd be more worried about any buried joints and what happens with water ingress.


    Also, when the inverter is cut off, how is (or just 'is') the DC string isolated ?  - If the sun us shining, surely there could well  still be dangerous voltages on the DC wires despite inversion ceasing?

    Mike

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  • 0
    Is it supposed to meet BS7671 ?  Or are there the equivalent of makers instructions that over-rule it ?

    In practice it may be more pertinent to ask are the cable routes out of the way and are they  well marked/ recorded  or are they likely to be ploughed up?

    Given the insulation monitor and ADS, assuming the cable has a jacket that will survive burial, I'd be more worried about any buried joints and what happens with water ingress.


    Also, when the inverter is cut off, how is (or just 'is') the DC string isolated ?  - If the sun us shining, surely there could well  still be dangerous voltages on the DC wires despite inversion ceasing?

    Mike

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