KevinP:
Thanks everyone. In this particular instance I believe route 4, via the local authority, would be appropriate but that the electrician who contracted to undertake the work in the first place should compensate the customer, ie pay for the local authority work. Thats is assuming the certificate is not issued anyway (despite not following the rules). You could argue the customer should have checked the electrician was able to certify the work correctly at the start, in practice its hard for a general member of the public to understand the nuances. Several of you commented on the inadequacy of the rules around Part P. As one person said, every electrician undertaking this work should be a competent person and registered.
Who pays for what is entirely a matter of contract.
If the electrician purported to be a member of a CPS, but was not, advise your neighbour to contact the relevant scheme. They may choose to pursue him or her: essentially, it is a matter of fraud. Trading standards may be interested.
It is not necessary to be a member of a CPS to issue an EIC. In fact, I don't think that any particular qualifications are required BS 7671 641 in a nutshell: the work must be verified and (641.6) The verification shall be made by one or more skilled persons competent in such work. "Skilled person" is defined as, Person who possesses, as appropriate to the nature of the electrical work to be undertaken, adequate education, training and practical skills, and who is able to perceive risks and avoid hazards which electricity can create.
Whilst a folder full of C&G certificates and membership of a CPS are good evidence that a person is skilled and competent, they are not, in fact, necessary to demonstrate the fact.
If the work was notifiable, it really was up to the householder to ensure that the trader belongs to a CPS. There is plenty of advice out there.
We're about to take you to the IET registration website. Don't worry though, you'll be sent straight back to the community after completing the registration.
Continue to the IET registration site