We are currently installing solar pv systems, and have had a third party at one of our installs carrying out an EICR. They have flagged a C2 for the RCBO we have used only being single pole.
In section 712 of BS7671 ‘Special Locations – Solar PV’ we cannot see a regulation that states that a double pole RCD is required. Any advice on this matter would be greatly appreciated.
Inverters in general should not be supplied from RCD protected circuits, as most RCDs and RCBOs are not bi directional, and therefore are not suitable for solar or battery installations. and as for double pole isolation this is the best I can come up with Because most systems use the 1 amp fuse/detection breaker between the array negative and safety ground. it turns a ground referenced system into floating power system--Which does need two pole breakers for safety
Because most systems use the 1 amp fuse/detection breaker between the array negative and safety ground. it turns a ground referenced system into floating power system
Point of order: Most PV installations in the UK are floating on the DC side by design and rely on double insulation for protection against fault plus insulation monitoring, with DC fuses where required for overload protection (in case of reverse current). Other countries' practices may vary, particularly when dealing with older installations. There are some which are functionally earthed (C21e tiles come to mind; from distant memory), which depending on the manufacturers instructions (and it does vary for technical reasons) could be earthed via + or -. For safety this will either have a resistor to limit fault current, or an OCPD (fuse/MCB) to interrupt fault current; in the latter case said device must be monitored and raise an earth fault alarm if it operates.
Inverters in general should not be supplied from RCD protected circuits
I don't disagree, albeit mainly coming from the angle of leakage currents causing maloperation or blinding of RCDs. But yes if an RCD (or other earth fault leakage device, including MCCBs with LSIG etc) is present upstream compatibility in all regards should be properly checked.
Because most systems use the 1 amp fuse/detection breaker between the array negative and safety ground. it turns a ground referenced system into floating power system
Point of order: Most PV installations in the UK are floating on the DC side by design and rely on double insulation for protection against fault plus insulation monitoring, with DC fuses where required for overload protection (in case of reverse current). Other countries' practices may vary, particularly when dealing with older installations. There are some which are functionally earthed (C21e tiles come to mind; from distant memory), which depending on the manufacturers instructions (and it does vary for technical reasons) could be earthed via + or -. For safety this will either have a resistor to limit fault current, or an OCPD (fuse/MCB) to interrupt fault current; in the latter case said device must be monitored and raise an earth fault alarm if it operates.
Inverters in general should not be supplied from RCD protected circuits
I don't disagree, albeit mainly coming from the angle of leakage currents causing maloperation or blinding of RCDs. But yes if an RCD (or other earth fault leakage device, including MCCBs with LSIG etc) is present upstream compatibility in all regards should be properly checked.
Inverters in general should not be supplied from RCD protected circuitsI don't disagree, albeit mainly coming from the angle of leakage currents causing maloperation or blinding of RCDs. But yes if an RCD (or other earth fault leakage device, including MCCBs with LSIG etc) is present upstream compatibility in all regards should be properly checked.
"In general" isn't always the case ... we can't forget TT systems "in general", but also I've seen an inverter arrangement actually supplied with 30 mA RCDs for the installation.
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