Because the requirements in 522.6.7 apply to cables.Which it is, why would you think not, for an alteration to a fuseboard post 17th introduction?
You aren't installing cables, so 522.6.7 does not apply to your work.
So would you insist on fitting RCDs even if every cable was either not within the scope of 522.6.6, or complied with one of 522.6.6 (i), (ii), (iii) or (iv)?This is the most important change to the 17th RCD - the requirement for whole house protection and a must!
The regulation which you believe applies to the job of replacing a rewirable fuse with an MCB in fact applies to cables concealed in walls or partitions.You are required to ensure that any new work that you do, conforms to the regulations, this would involve RCD protection as a minimum.
i.e. not the new work which you are doing.
I'm not, but it is inconsistent for you not to say that must be done.You're not suggesting the installation is ripped apart, to conform to the 17th?
But you haven't pointed to a regulation which says that.So FOR THE FOURTH TIME OF ASKING, why do you insist that additional work must be done in order to bring the rest of the installation into compliance with 522.6.7 but not a single other one of the many regulations with an equal status in BS 7671:2008? What is it that you feel you cannot do unless you make what's already there comply with 522.6.7 but you can do without making what's already there comply with 522.6.5, 522.6.8, 522.6.5, 521.10.1, 526.3, 522.8.10 etc etc etc?
And why?
I think you've lost the plot, I have already stated the requirement to protect the existing installation by front end RCD's!
You appear to be making that claim over and over again because of a regulation which applies to the installation of cables, not the work you are doing.
So FOR THE FIFTH TIME OF ASKING, what is it that you feel you cannot do unless you make what's already there comply with 522.6.7 but which you can do without making what's already there comply with 522.6.5, 522.6.8, 522.6.5, 521.10.1, 526.3, 522.8.10 etc etc etc?