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

mapj1

Yeh all mapped out and a controlled site with clear Rams in place 

Disconnecting the load (inverter) will greatly reduce the current flow. 

Mechanical protection is in place on all cables exiting ground

Thanks all for your replies

client stating that a PV solar Generation site built on agricultural land is non compliant


Did the client require/specify a BS7671 compliant installation and left it to the designer/constructor/inspector&tester to achieve this?


Regards


BOD

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

I guess they're thinking of reg 522.8.10 of BS 7671 which requires cables buried in the ground to have an earthed metallic sheath or earthed metallic armour or be in a duct or conduit that provides equivalent protection. That might well be a peculiarly UK requirement (I've seen buried cables on the continent without any armour.)


There is a difficulty for circuits that aren't protected by ADS in that an earthed  armour/sheath then doesn't in fact provide much protection from shock but BS 7671 seems to overlook that.


If you feel that the arrangement you have provides at least the same level of safety as a compliant one, you always have the option of a 'deviation'.


   - Andy.