Most of this is probably known to you
Any electrical installation that a competent person carries out needs to be tested and the results recorded on a certificate issued
The certificates used are either the genuine IEE model forms or all singing and dancing certificates compiled by others ( niceic,napit,elecsa and uncle tom cobbly and all )
A competent person is someone who believes they have the skill to do electrical installation
There are registration bodies who assess the competence of a firm or an individual and if successfull they are registered with that scheme
For electrical installation,domestic commercial industrial, it is not necessary to belong to any scheme
Without registration the firm or person may find work difficult to obtain, because the customer may specify that belonging to a scheme like Niceic is required by them,
In the domestic market,there is a building regulation called part p
Part p says that most major electrical work in dwellings need to be notified to building control before being carried out,a fee is payable dependant on the size of job and where you live
There is another way to comply with the above domestic notification rule
A person or firm can register as a competent person with the niceic napit or elecsa,they are assessed by them and if successful they can self certify that the work they carry out in dwellings complies with building regulation part p and they avoid having to notify building control or having to pay the notification fee
So in a nutshell,anyone can do electrical installation,anyone can sign a certificate but proof of competency may be an advantage in industrial,commercial and domestic installation