CSA Size on Extended Circuit

[besp]

Hi all,

Can I have an opinion as to the following quote in relation to a domestic installation:

"When connecting into an existing circuit it should be noted that cables should be of the same CSA or at a reduced size, taking into account the requirements for current carrying capacity of the circuit being modified"

Is it an accurate statement?
What regulation would this statement be referring to?

Thanks.

 

[Richard Burns]

When connecting into an existing circuit it should be noted that cables should be sized by taking into account the requirements for cable current carrying capacity of the circuit being modified.

Would be a better statement.

A smaller csa than the original is unlikely to be suitable if the original circuit was designed correctly. The cable would usually be sized originally to be as small as possible so as not to waste money on excess copper.
There should be no problem with the regulations on providing an increased csa but it would be a waste.

 

[Engineer54]

When connecting into an existing circuit it should be noted that cables should be sized by taking into account the requirements for cable current carrying capacity of the circuit being modified.

Would be a better statement.

A smaller csa than the original is unlikely to be suitable if the original circuit was designed correctly. The cable would usually be sized originally to be as small as possible so as not to waste money on excess copper.
There should be no problem with the regulations on providing an increased csa but it would be a waste.

Unless of course, if there is a suitable sized fuse to cater for the smaller sized cable at the point of cable size reduction. Such as, via a FCU!! ...lol!!