On 16/11/2019 00:24, Tricky Dicky wrote:

I spoke to the BCO today and the outcome of the conversation is that
he insists I include a Surge Protection Device (SPD) in the CU and
looking into the calculation required to avoid inclusion and the faff
collecting all the info it is probably easier and gets the job moving
just to fork out the £44 and be done.

Hmm, another box ticking exercise for the BCOs...

So this is hopefully the final layout of all the protection devices
in the CU:

https://www.dropbox.com/s/vdv6ch8q1p...yout.docx?dl=0

AS the SPD is not connected to the busbar I have included it at the
end of the first section containing the Garage MCB and the two RCBO
devices. The issue is that it needs feeding from a MCB 16 - 32A. The
manufacturers recommend a 32A ring main. So does it matter which of
the two devices as indicated on the diagram is used?

Yes, you want it to be in circuit all the time. If you feed it from a
circuit on RCD1, then should that RCD trip, you would lose surge
protection to the circuits on RCD2 and also the non RCD protected
section of the CU.

So feeding from a MCB on the non RCD section of the board would be
preferable IMHO. I would probably swap the alarm and FF MCB positions
and then feed it from the Alarm one, since you probably don't want to
add any extra trip risk to the FF circuit.

Finally, I have added a separate isolator switch and planned
initially to feed the tails from it into the bottom of the CU but
would now like to fit a socket below the CU and with not much room to
play with it would be convenient to feed them through the top? There
are suitable knockouts in the top and the instructions say top
feeding is possible but with the convention being to bottom feed and
CU is situated below a kitchen worktop would anyone raise any
objections?

No, although IP requirements are tighter for cables entering the top.
The easiest way is to use a tails gland kit.

I know I should have asked the BCO but had other things on my mind
and I do not want to get into another conversation that will cost me
money!

Yup, sometimes less conversation is better!


--
Cheers,

John.

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