Confirming my understanding of reference method 100

[Licklieder]

I am looking to split the ring in my flat to install some additional sockets whilst installing thermal & acoustic insulation. My intention is to run new 2.5mm T&E cabling directly clipped to the existing, plastered brick wall horizontally from the existing socket to the new location. The wall will then be insulated with 50mm of acoustic insulant and boarded out.

Am I correct in my interpretation of the reference methods that method 100 applies ? And that from table 4D5 that the current carrying capacity of each cable will be 21A and thus that this is an acceptable installation ?

 

[JohnW2]

I am looking to split the ring in my flat to install some additional sockets whilst installing thermal & acoustic insulation. My intention is to run new 2.5mm T&E cabling directly clipped to the existing, plastered brick wall horizontally from the existing socket to the new location. The wall will then be insulated with 50mm of acoustic insulant and boarded out. ... Am I correct in my interpretation of the reference methods that method 100 applies ? And that from table 4D5 that the current carrying capacity of each cable will be 21A and thus that this is an acceptable installation ?

I think you probably mean method 102 (method 100 is the corresponding one for ceilings), but that doesn't alter the answer. I would personally think that what you say is 'at least true' - although, of course, others might disagree! Your situation is a little unusual, in that there is not usually a masonry wall to 'clip direct' to beneath the insulation - but if it is so clipped, it could just be that a more generous CCC (even, conceivably that applicable for Method C) might be applicable. However, since 21A is enough for your ring, you don't even need to think/worry about that.

Someone is bound to point out that this new cable will (if <50mm from surface of the wall) have to be RCD protected - so, if the circuit doesn't already have RCD protection, that would have to be addressed.

Kind Regards, John

 

[Licklieder]

Yes, you're right. I do mean method 102.

Had the consumer unit replaced a while back so circuit should already be protected with and RCD but will check. I think once the plasterboard goes up the distance from to the cable will be > 50mm but thanks for pointing it out.

I'll run it past the BCO anyway when I next call her since the rest of the work is notifiable.

 

[JohnW2]

Yes, you're right. I do mean method 102. ... Had the consumer unit replaced a while back so circuit should already be protected with and RCD but will check. I think once the plasterboard goes up the distance from to the cable will be > 50mm but thanks for pointing it out. ... I'll run it past the BCO anyway when I next call her since the rest of the work is notifiable.

That's fair enough - and you're welcome. It will be interesting to see what other opinions are expressed here!

In passing, as we touched on in a recent discussion here, I'm not actually convinced that it's really possible to 'properly satisfy' the requirements for Method 102 with a standard plasterboard+stud+insulation wall - since it's not easy to see how one can sensibly ensure that the cable is in good thermal contact with the inner surface of the plasterboard for its entire length!

Kind Regards, John