You cannot post a reply to this discussion. If you have a question start a new discussion
Advice Please - Mains cartridge fused Isolator switch or MCB and isolator Switch.
Former Community Member
I manage a residential mobile home park with homes that individually have mains supply TT coming to a meter box recessed into a breeze block shed. The tails then come from the meter into the shed and into an old style bakelite rewireable 40a fused isolator switch. There is then an outgoing 10mm SWA cable running from the isolator switch underground from the shed to the home and then into the consumer unit for the home (total run approx. 8 to 10 metres). Having had an EICR for one of the homes I have been adviced that these isolator switches will need to be replaced as the swa cable is not properly terminated (it is not glanded in to the isolator switch and the wire stranded sheathing is twisted together and connected to the earth block.) My question is can this isolator switch be replaced with an 18th edition 3 way metal enclosure with double pole isolator switch and 40a mcb or should it be replaced with a 60a (or 40a) cartridge fused double poled mains isolator switch. Additionally would it a be a good idea to put a 60a RCD into the shed and either use a five way enclosure (in place of 3 way enclosure) or a 2 way enclosure fed from the cartridge isolator switch. All the homes have a standard consumer unit containing either a 60a or 80a RCD and 3 to 5 suitable MCB's (32a, 16a, 6a).
Pardon Andy, are you suggesting that there is no RCD protection on the distribution circuits? I thought the question, defect, and suggested fix is to the switchfuse(s), not the overall supply. It is true it may be TT, or that the person asking is not sure, but I am feeling that the description is incomplete. Surely if TT an Earth electrode would be mentioned, and the term Earth block, presumably the MET, surely suggests it is TNC-S? No installer would fit a block and no Earth connection to it and probably would have ignored the SWA armour as well, and left it floating. Even if the Earth is missing at the distribution point, each home will have an Earth electrode, otherwise where would the internal Earth system be connected? I suppose it could have been just linked to the SWA, but then unless it is new this would have shown up on any inspection, EICR or new work since. Unless someone is digging up the SWA and damages it there is in reality very little risk whatever, but perhaps the original poster would clarify it for us? The home EICR should have picked this up upon Inspection shouldn't it, they got the switchfuses without any trouble?
Pardon Andy, are you suggesting that there is no RCD protection on the distribution circuits? I thought the question, defect, and suggested fix is to the switchfuse(s), not the overall supply. It is true it may be TT, or that the person asking is not sure, but I am feeling that the description is incomplete. Surely if TT an Earth electrode would be mentioned, and the term Earth block, presumably the MET, surely suggests it is TNC-S? No installer would fit a block and no Earth connection to it and probably would have ignored the SWA armour as well, and left it floating. Even if the Earth is missing at the distribution point, each home will have an Earth electrode, otherwise where would the internal Earth system be connected? I suppose it could have been just linked to the SWA, but then unless it is new this would have shown up on any inspection, EICR or new work since. Unless someone is digging up the SWA and damages it there is in reality very little risk whatever, but perhaps the original poster would clarify it for us? The home EICR should have picked this up upon Inspection shouldn't it, they got the switchfuses without any trouble?
