Good afternoon, my name is ***** ***** I will assist with your query today.
Can you confirm if this is a ring or radial circuit and if your using 2.5mm twin and earth?
Hi. Not sure if my last reply registered ......... would appear to be a radial circuit as there is nothing else in or out, and nothing else on that particular MCB. 2.5mm T&E was used
Sorry for the delay in responding, a spur should only be used if your have a ring main not from a radial.
You cant fit a 32A MCB to a 2.5 radial as the load is to great for the cable the maximum you can go to on a radial with 2.5 TE is 27A, so if you want to upgrade the MCB you can only go to a 20A otherwise will need to run a second 2.5mm and make it into a ring to use a 32A MCB.
So is the current set-up wrong too, as it would appear that the garage was built with a double socket, and the second socket - a spur from the first - was added at a later date?
It depends if its a spur off the radial, or if they just added an extra socket on to the end of the radial.
It would appear that the builders installed one double socket, using 2.5mm T&E cable from the fusebox (no.11, B16 MCB). There is nothing else served from fuse no. 11 so it would logically just be a 2.5mm cable from the fusebox to the double socket.A previous owner has then added a spur from that socket, to provide a second double socket. We want to add another spur so as to gain a third double socket. The current situation has both double sockets within a metre off each other, which in a double garage is not very practicable. Our desire is to have three double sockets spread out around the garage
Right so this is achievable providing your 'spur' from the end of the radial, so the original socket (by the builders) has one T&E in (from the consumer unit) and one T&E out to the second socket (which may be the one you install or the one the previous owner installed), you then have the second socket with the T&E in from the original socket and one T&E out to the final (third socket).
That then gives you 3 sockets on the radial if that makes sense, none of them are a spur off the radial.
Please let me know if you need any further advice John.
Thanks for that ....... last question now:
Your explanation is to daisy chain them, so 2.5mm T&E cable from MCB to first (original) socket - installed by builder, then original socket to second socket - installed by previous owner, and then second socket to new third socket - to be installed by us. Would there be (in theory at least) anything stopping us continuing beyond the third socket to a fourth one?
Hi John, sorry I needed to verify something with my colleague.
You are correct in terms of daisy chaining them (this is what \ how a radial circuit is constructed).
Based on the 17th (latest regs), you should really be using a 20A MCB if you have more than one double socket on the 2.5mm radial.
So to answer your question your current setup doesnt meet the current standards as you already have 2 double sockets (I assume) on a radial protected by a 16A MCB, if you change the MCB to 20A (which is the maximum you can go to on a 2.5mm radial), you can have unlimited number of sockets (4 in your example), the only constraint is the area covered is no more than 50M squared.
It does sound strange it goes from on double gang socket on 16A and unlimited on 20A circuit, but they are the current guidelines, which building control work to.
Does that now clarify what is required for you John?
Yup, I know now where I stand with it and what I can do to achieve what we need. Many thanks