Existing installations
How should an old electrical installation be renovated in Spain?
Start with inspection, testing and comparison with available records. Age alone does not mean every component must be replaced, but hazards, deterioration and parts affected by an extension must be corrected and properly documented.
Priorities
Remove immediate hazards first: accessible live parts, overheating, degraded insulation, missing protection or discontinuous earth. Then plan capacity, new uses and maintainability.
Define the scope
A partial renovation must clearly distinguish retained and altered work. The project or MTD, diagrams and certificate should describe reality and not imply that untested sections were replaced.
For the next part of the decision, see the guides to Legalising an existing installation and No electrical records.
What can be retained when renovating old wiring?
The building’s age alone cannot establish which cables and protective devices can remain. Conductors, joints, earth continuity and insulation need assessment alongside the alteration history. A new distribution board can still feed deteriorated circuits; replacing the board does not amount to rewiring the entire property.
Before walls are closed during refurbishment, establish future loads such as an electric cooker, air conditioning, water heater or EV charger. These can change demand and circuit arrangements. The engineer should compare those plans with the existing feeder, board and circuits. Separating urgent repairs from planned improvements helps organise work without treating essential safety corrections as optional.
Article 2 of the REBT distinguishes new installations and modifications or extensions from earlier installations. The applicable requirements depend on the scope and historical evidence. Final documents should identify retained and altered parts and the checks performed, rather than imply that partial work constitutes a complete renewal.
Partial upgrade or complete rewiring?
An old installation should not be replaced solely because of its age. Check materials, insulation condition, protective continuity, boards, present loads and whether existing circuits can safely remain. A home with sound circuits needing a new kitchen supply is a different case from one with damaged wiring and unreliable records.
Plan for likely future uses: air conditioning, induction cooking, EV charging and solar PV can affect the design. Document what is kept and changed because the old CIE will not describe the renovation. Separate investigation, electrical work, builders' finishes and paperwork in the quote so offers with different scopes can be compared.
A sensible renovation sequence
- 01
Find CIE, project, drawings and history.
- 02
Inspect and test circuits, earth and protection.
- 03
Set risks, future uses and power.
- 04
Classify project/MTD and OCA needs.
- 05
Build, verify, certify and register.
Frequently asked questions
Does an old installation automatically fail?
Not on age alone. Applicable rules, alterations, condition and safety are assessed; altered parts must meet the relevant framework.
Can only the board be changed?
It may be one improvement, but new protection must coordinate with existing cables, earth and circuits.
Regulatory basis and official sources
- Spanish Low Voltage Regulation (REBT) and technical instructions — BOE
- Balearic low-voltage installation registration (UDIT-001) — CAIB
Always check the current version of the rule and the administrative procedure that applies to the specific case.