PV Install and Existing RCD's

[Kevin]

OK, this may be an obvious question, but can a PV Installation be fed from the existing CU, if the CU contains an RCD, or would you be required to split the tails, and put the PV on its own MCB within it's own enclosure? Was told today by an NIC inspector that they require their own enclosure and RCD and cannot share one with other circuits, is this correct? Have read through the DTI guide and can't see a mention of this.

Many thanks

K

 

[SolarCity]

There is no reason why this should be the case. We tend to do this to keep things simple but I can think of no regulation or guideline that suggests that we should all be doing it.

 

[Kevin]

Thanks BiggsSolar, I've looked and can't find anything either. The NIC inspector was actually speaking to my mananger and not me, but by all accounts said the return feed from the PV installation caused an imbalance and problems with existing RCD's (though I can't see why), and he wanted a separate enclosure for the PV system, which is a pain to fit when space is limited.

 

[SolarCity]

but by all accounts said the return feed from the PV installation caused an imbalance and problems with existing RCD's (though I can't see why)

I can kind of see where he is going with that and we simply avoid installing on an RCD. The actual regs on this are pretty muddy as far as I can see but the way I interpret them is that an RCD is simply not required (assuming other factors don't call for it, of course)

 

[Kevin]

OK, I see, that's fair enough, trouble is most of the properties we work on have been rewired, and a new split RCD board installed (non high integrity) so any new circuits utilising the existing CU would share an RCD.

 

[SolarCity]

Can the CU not be adapted so that you can install a seperate CB that is not RCD protected?

 

[Kevin]

Not sure, there is limited space, usually only one spare way left and only two neutral bars, one for each RCD.