The short answer: what it is and who issues it
The «boletín», CIE or butlletí is the certificat d'instal·lació elèctrica de baixa tensió, the low-voltage electrical installation certificate (CIEBT in Catalonia). It is issued and signed by an empresa instal·ladora habilitada, an electrical installation company listed in the Catalan RASIC register. You cannot issue it yourself, even if you did the wiring with your own hands.
The key point: under Decret 192/2023, extensions and modifications of the interior electrical installation of a home are not entered in the RITSIC register. In practice, after rewiring a flat you normally have nothing to file with the administration: you receive a set of documents from the installer and keep them. Filing is needed for new installations, such as a new house or a new supply point. Then the owner (titular) submits a declaració responsable (responsible declaration) online through Canal Empresa, free of charge.
When you need the certificate
A certificate is issued after any work that creates, extends or modifies an electrical installation. Rewiring a whole Eixample flat, running new kitchen circuits for an induction hob and oven, moving the consumer unit, adding a line for air conditioning or an EV charger: all of that is done by a registered installer, who hands over the certificate at the end.
New installations are a separate case. A new house in Castelldefels, a new supply point or a change of use (a former office becoming a flat) need an administrative filing, not just the electrician's paperwork. A single-family house above 50 kW needs a project signed by an engineer instead of the simplified memòria tècnica de disseny, and under the REBT a swimming pool with more than 10 kW installed needs an initial inspection by an authorised control body (OCA).
Distribution and retail electricity companies usually ask for the certificate when you sign a new contract or raise the contracted power. So even when nothing goes to the administration, you will need the document.
What the installer must hand over
Under ITA 12 of Decret 192/2023, the owner must keep for the whole service life of the installation: the memòria tècnica de disseny (MTD, technical design report) with the single-line diagram (esquema unifilar); the CIEBT certificate itself; the use and maintenance instructions; and the documents and certificates for every later extension or modification. Installations with a project add the project and the certificat de direcció i acabament d'obra (site supervision and completion certificate, model ELEC-4).
The certificate names the company, its RASIC number and its category (basic or specialist). An electronic signature replaces the company stamp. Installers must keep certificates digitally for 10 years from commissioning, but do not rely on that: when you sell the flat, you are the one who needs the papers, not the electrician.
From you, the installer will usually need your DNI or NIE, the address and cadastral reference, and your electricity contract details (the CUPS supply number is on your bill).
Step by step: from choosing an installer to the declaration
First, check the installer. Ask for their RASIC number and category and verify them in the register's public search on the Generalitat website. Second, agree on the documentation before work starts: an MTD with a single-line diagram for a flat, a project for larger installations. Third, the work and the tests: insulation, earthing, residual current devices. Fourth, the company signs the CIEBT and gives you the full document set.
If it is a modification inside a flat, that is the end of it: the certificate goes to the electricity company if you change power or contract, and the originals stay with you.
If the installation is new, a declaration is due. The procedure is called «Presentació de la declaració responsable per a instal·lacions elèctriques de baixa tensió (posada en servei, modificacions i baixa)» and is online only, via Canal Empresa. Log in with idCAT Mòbil or a digital certificate, enter the installation data, attach the certificate and documents, sign the declaration and submit. The owner, their legal representative or an authorised agent may sign, so installers often file it for you with an authorisation. There is no fee. You get a receipt on submission, and once checked the administration issues a certificat acreditatiu de la inscripció (proof of registration), available in your private area on Canal Empresa.
Afterwards: inspections and record keeping
An ordinary flat has no periodic inspections of its electrical installation. A residential building's common installations above 100 kW are inspected every 10 years, and installations that needed an initial inspection (a pool above 10 kW, for example) every 5 years. A control body (Organisme de Control) carries it out, and it cannot be done if the owner does not have at least the single-line diagram.
The result is favourable, conditional or negative. A conditional result gives you up to 6 months to fix the defects; a new installation with that result is not connected until they are corrected. A negative result on an installation in service is reported to the administration.
Keep all certificates in one folder, paper and digital. Every later job adds its own certificate, and a buyer will see the full history when you sell.
Common mistakes
Hiring an electrician who is not in the RASIC register. They cannot issue the certificate, and the work will have to be checked and certified again.
Not getting the single-line diagram. Without it no inspection can take place, and the next electrician has to start from scratch.
Saving money on cable. ITA 12 requires Cca-s1b,d1,a1 cables (flame-retardant, low smoke) in the interior installations of homes.
Leaving new circuits without a protective conductor. If an older Eixample building has no earth on its supply line, extending or modifying the flat means installing earthing and taking the protective conductor to every point of use.
Losing the paperwork. Rebuilding the file years later is hard, and you will be asked for it when you sell or change your contract.
Rules change, so check the current procedure page before work starts. If you would rather not deal with it yourself, BCN YARD handles the paperwork together with the renovation.