However, my builder has said he knows a qualified electrician who will sign off all three parts of the EIC. I'm not sure how kosher that is,
Really?
You are really not sure how kosher it is for someone to lie on an official document?
but am I legally above board if someone other than the person who did the work signs off all three parts (given that he's fully qualified to do so)?
Can't speak to the actual legality - I suspect that anyone would have a hard time proving that you'd done anything unlawful. But you know it would be wrong, and morally you would not be above board.
Speaking of which, what registration must he have to sign off the third part of an EIC and to issue an EICR? Is it NICEIC, Registered Competent Person, NAPIT, or a combination thereof?
It's none.
There are no formal qualifications needed to sign any part of an EIC, or an EICR. In the case of a council looking for such certificates or reports as proof that the electrical work complies with Part P they may well insist on evidence of competence via qualifications and membership of a Competent Person scheme, but legally your Auntie Flo could sign any or all parts of an EIC. The question would be what is the signature worth?
Disclaimer. You may not have an Auntie Flo, or if you do she may be a qualified electrician.
I think it's best to leave morals out of this for the sake of keeping the discussion on track and this not becoming a drawn-out Internet debate. Reason being, this is about signatures on a sheet of paper, not whether the work has been done properly. I believe the work has been done properly as I have monitored it rigorously and had daily discussions with the builder as to his work, and I've checked everything - and this would have been my only option until the EIC existed (that, or faith). The sheet of paper we're talking about didn't exist until 2005. It does not make all work prior to 2005 immoral.
All I want is for my tenants and property to be safe, for the electrics to be proper and functional, and for the works and me to be legal. If someone other than the person who did the work signs of all three parts of the EIC, if that still means the tenants and property are safe, the electrics are proper and functional, and the works and me are legal, then I'm happy with that. If it means the person who signs it is doing something illegal at risk only to himself, then that's his prerogative.
That said, if there's no real advantage to him signing the first two parts if he's going to sign the third part (because the third part effectively endorses the first two parts), then I see little point in him taking this risk. Similarly, if there are legal implications for me, then I would obviously prefer my builder to sign the first two parts.
I'm new to this, hence why I'm on here asking questions. But I've also heard that some inspectors are not as invasive or thorough as the online official literature makes out. Some just come along, do some basic tests, maybe have a chat with the electrician to make sure he has a clue, and then sign it all off. Others are more serious and by the book.
I don't have first-hand experience of an inspection (yet), but I'm learning, and this project is a learning experience that I will definitely know more about after for when I go into my next big project as to Building Regulations, EICs, etc.