As said no qualification required, however you must have the knowledge to do the work safely for yourself and others.
The problem is as always, if some thing goes wrong, because it has gone wrong, it points to you not having the knowledge, so you want some thing to show you do have the knowledge. About the cheapest exam which really only shows you can read a book, but is seen as showing you have electrical knowledge is the exam to show your aware of the regulations, it has changed number 16th edition was C&G2381 then 17th was C&G2382 and I expect there is a new number for 18th edition of wiring regulations.
To show any HSE inspector your able to do the work safely you would also need to show you have access to test equipment, as to what test equipment not so sure.
Before the
Emma Shaw court case I was not really worried about qualifications, however in that case an electricians mate was asked to take readings which entailed plugging in a tester and writing down what it said when he pressed the button, he did not need to interpret the results, simply write them down, however it seems the meter showed OL or some other non numeric reading, so he asked in the canteen and wrote down what they suggested. This resulted in his foreman being found guilty for using unskilled labour.
The foreman could hardly argue the guy had the skill required because his actions showed he did not. Through out my working life there have been similar court cases for nearly every trade, and when you read them, one thinks there by grace of god go I.
So to fit a FCU what do you need to know? Well we know it is not permitted to take a second supply from an unfused spur, so you need to identify the circuit you are tapping into, even when you know the load is so low, you still need to follow the rules, you need to test that the RCD supplying the new FCU will trip within the prescribed time, and current, and that the cables are within safe zones. And be able to get all the information required to fill in the minor works certificate.
In real terms issuing a minor works certificate is your get out of jail free card, it shows you tested and inspected as long as the readings put down actually match the actual readings, so if your certificate says the ELI at origin is 0.23Ω and when some thing goes wrong the HSE inspector also gets 0.25Ω then it is close enough for him to think you actually took all the readings on the certificate, however if you write down it's a TN supply and it is actually a TT supply then it will show you didn't know what you were doing.
So I would say any electrical qualification for radio hams exam to C&G2381 even if out of date, shows you have studied and have basic knowledge required, and of course the filling in and issuing of minor works certificates. So if a plasterer puts a nail through your cable, you can show it was OK when you left, nail must have gone in after you left. Which in turn means actual readings, not guessed readings. Which in turn means loop impedance meter, RCD meter, insulation tester, and low ohm meter, and some method to show the meters are working as they should.
And the ability to answer questions from HSE as to how you knew the supply was suitable. From what I am told the new 18th is stricter as far as RCD protection goes, and the old idea of using a RCD FCU with Ali-tube cable supplying it is no longer allowed? So before I could start fitting alarms, I would need to buy 18th edition and study the changes, so I know what is permitted, even with a degree, and I would also need to buy myself a new test set, so looking at around £800 to get what I need to start, I considered re-wiring mothers house, but between LABC fees and getting new test gear, plus speed, it was not worth it, got some one else to do it.
