Where did you find him? Was he registered with any of the competent person schemes - NICEIC. NAPIT etc?
Got him from RatedPeople, he had quite a few positive recent reviews of local work near me, which I take more interest in than the stars rating.
He was NAPIT registered. I did check before he started work that his number was valid - I contacted NAPIT directly.
I wouldn't have touched anyone without something I didn't recognise.
I was thinking about this more since last night.
He did have an apprentice with him on the job and I'm wondering if he got the apprentice to do some of the testing - and then forgot to check the results. He actually did a few tasks for me (not just the CU) and the quality of his work seems fine. The items pointed out in the test results seem very basic errors (certainly now they've been explained to me!).
The work was done about 18 months ago, so I can imagine if I call him to discuss the results then he will be 'overjoyed' to hear from me, but you never know he may do something about it.
His NAPIT number and certificate number are on the documents - is it possible for him to retrieve it electronically or do I need to photocopy/scan and send through?
I am aware that at the very least if I sell the house, these certificates will be asked for and I don't want any grief in a potential sale.
Going back to the original post - I think I'll leave the MCB alone.
I'm now aware than the existing certificate does specifically mention the 16A MCB, it might be a bit obvious if I do swap anything (albeit it's really a Type B MCB, not the Type A on the form!)