Funny seeing this thread today, because first remedial of the morning I noticed this little baby. Wylex RCBO'S in a Contactum CU and somebody has missed the busbar. Still melted the internal plastic just lucky it had only central heating on it.
Everybody has there own way, I've just adopted the fastest way of doing it. we use wylex at work and install these every other day. I don't fire seal entries either although I only make holes large enough for the cables and no more.
Looks ok. Would never have bushed from 2x2 Plastic into board.
quicker to go with back plate and rear entry or 2x2 trunking Into top left corner of DB with 2" hole grommet stripped or bushed.
I've re-wired old flats which at a guess were circa 1970's and they were wired in a type of T&E with a heavy duty steel wire braiding on the outside of the cable, I've never seen it since but it would be ideal for situations such as this.
As far as the actual under floor matt goes, its under the floor therefore I would not class it as in a zone rather in a location containing a bath or shower - however it should be RCD protected and have an earthed grid/sheath.
It would be very unlikely of the tails being damaged and touching the metal case of the DB if you use the appropriately sized gland and carrying the double insulation of the tails directly upto the termination point. There is little possibility of severe damage to the tails once inside the C.U.
Yes they did mess up there. I would probably put a 100mA type S in place of the main switch and use apprpriate glanding with double insulated tails going directly into the terminals of the RCD.
Where does he live? Darke's have been around for years, I know quite a few lads that have done there apprenticeships with them and you can't go far wrong.
It would be the obvious choice if deciding between the two options you've given.
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