Went to visit a customer who requested me to install 2 wall lights and one pendant light, the wiring was already in place, as this is an extended and rewired house (not by me).  I turned off the mcb that was installed for this lighting circuit and to my surprise the mcb value was 16A for 1.5 mm2 wire, I found 2 other lighting circuits with 16A mcb's.
I had a spare 6A mcb and changed one of the 16A mcb with the intention to change the other 2 after the week end.
I am sure that I don't have to explain the reasons why I changed this mcb, my question is:  As I'm still doing part 2 (last exam June 2005), I can't register yet, but the original job is not notifiable so i could do it .  Your opinion concerning the mcb part, as it is a simple thing to do but have i done the right thing considering BS7671 and part P?  ???
Thanks Albert

exactly how does a lighting cuircuit in 1.5mm on a B16 not comply?

[quote author=plugwash  link=1111252515/0#2 date=1111284507]exactly how does a lighting cuircuit in 1.5mm on a B16 not comply? [/quote]

I think by the fact that the cable can carry less current than the mcb, the cable is not protected...

[quote author=akuk  link=1111252515/0#4 date=1111314353]

I think by the fact that the cable can carry less current than the mcb, the cable is not protected... [/quote]


what you must remember is thats not actuly true  :P

it depends on instalation methods, length, disconnection, earth loop, ect ect

ive seen immersions wired in 1.5 on 16s

but i wouldn't accept it if i was running the site!
same as i wouldent accept the CCT you have just found.

but remember lighting dosn't have to be a 6 or a 10 ;)

ss

[quote author=L.Spark  link=1111252515/0#7 date=1111333859]As SS said..

The point is that any rating can be used as long as the cable has that continual current carrying capacity under installation conditions  8) [/quote]

You are 100% right in a general case, in this case we are dealing with specific  and known parameters.  According to table 6D1 (OSG), the best you can get for 1.5mm2 is 20A metode 1, (no cf), this circuit supplies the upstairs lighting, goes through the loft, under the boards, which are covered by thermal  insulation...I don't beleive that there in any place where you will (or should) not use correction factors.  Methode 4 will allow only 14.5A before using CF...