Electrical inspection in Portugal is governed by the RTIEBT (Regras Técnicas das Instalações Elétricas de Baixa Tensão, Portaria n.º 949-A/2006) and regulated under Decreto-Lei n.º 96/2017, de 10 de agosto (DL 96/2017), amended by Lei n.º 61/2018, de 21 de agosto. The law establishes mandatory inspections for new and renovated installations and for specific commercial and public-use properties — but standard residential properties are explicitly excluded from mandatory periodic inspection. This means a property built decades ago with an electrical installation that has never been verified can be sold without any authority checking its condition. Under Decreto-Lei n.º 10/2024 (DL 10/2024), which removed the last remaining verification checkpoint at the deed, that risk transfers entirely to the buyer at the moment of signing. A pre-purchase inspection by an OE-certified engineer, which assesses the electrical installation, is the only available protection.
Table of Contents
- What law governs electrical installations in Portugal?
- When is an electrical inspection legally required?
- Why are residential properties not covered by mandatory periodic inspection?
- What does a pre-purchase electrical inspection assess?
- What are the most common electrical problems found in Portuguese properties?
- How does the electrical system interact with the buyer's liability under DL 10/2024?
- Frequently Asked Questions
What law governs electrical installations in Portugal?
Electrical installations in Portugal are governed by the RTIEBT technical standards (Portaria n.º 949-A/2006, amended by Portaria n.º 252/2015) and the regime of private electrical service installations set out in DL 96/2017, with DGEG (Direção-Geral de Energia e Geologia) as the primary supervisory authority.
Portugal's electrical installation framework has two distinct layers. The first is the RTIEBT — the Regras Técnicas das Instalações Elétricas de Baixa Tensão — which sets the technical design, execution and safety standards for all low-voltage electrical installations. Every new or renovated installation must comply with RTIEBT regardless of property type.
The second layer is DL 96/2017, which replaced the previous regime and established the current system of inspection, certification, registration and periodic oversight for what the law calls "instalações elétricas de serviço particular" — private electrical service installations. DL 96/2017 categorises installations into three types: Type A (generating installations), Type B (high-voltage client substations), and Type C (low-voltage consumption installations, which covers standard residential and commercial properties).
Oversight responsibilities are split between DGEG (technical supervision and licensing of inspectors) and ERSE (market oversight and service quality regulation). ASAE (Autoridade de Segurança Alimentar e Económica) has enforcement powers. Inspections are carried out by accredited Entidades Inspetoras de Instalações Elétricas (EIIEL) — private bodies registered with DGEG. InspectOS works with EIIEL-accredited engineers for formal electrical compliance assessments.
When is an electrical inspection legally required?
Under DL 96/2017 and Lei 61/2018, a formal electrical inspection by an accredited EIIEL is legally required before a new or renovated installation can connect to the public grid — but for standard residential installations below 6.9kVA, the initial inspection requirement is waived, requiring only a term of responsibility from the installing technician.
The law distinguishes between initial inspections (at the point of connection) and periodic inspections (during the installation's operational life).
Initial inspections at connection. Under DL 96/2017, Art. 4, most installations require a declaration from an accredited inspector before connecting to the public electricity grid (RESP). Standard residential installations up to 6.9kVA are an exception — they require only a declaração de conformidade or termo de responsabilidade from the installing technician, without a full EIIEL inspection.
Periodic inspections. DL 96/2017, Art. 19 establishes mandatory 5-year periodic inspections for installations not subject to supervision by a permanent technical manager. The categories subject to this requirement include commercial premises above specific power thresholds, public venues, hospitals, schools, sports facilities, and other establishments receiving the public. Standard residential installations are explicitly excluded from this mandatory periodic inspection requirement, as confirmed by the Instituto Eletrotécnico Português (IEP), which noted that DL 96/2017 "não considera nesse grupo as instalações do tipo residencial."
What this means in practice: a residential property can have an electrical installation that is decades old, partially modified by non-certified technicians, and never formally re-inspected — and no authority will check it before the property is sold.
Why are residential properties not covered by mandatory periodic inspection?
The explicit exclusion of residential installations from DL 96/2017's mandatory periodic inspection requirement was flagged by the IEP as a significant safety gap, because residential installations frequently undergo informal modifications over decades without any technical verification.
The IEP's published commentary on this gap is direct: residential installations are "as que, ao longo dos anos vão sofrendo alterações para adaptação às novas necessidades, alterações essas frequentemente executadas pelos próprios utilizadores, sem qualquer tipo de habilitação técnica para o efeito" — modifications carried out by residents without technical qualification that can leave installations in unsafe or non-compliant states.
In Portugal, residential buildings have an average age well above 30 years in most urban markets. 68% of the buildings in the Lisbon metropolitan area predate the seismic-protection legislation approved in 1958 (Público, February 2023), and many of those same buildings have electrical installations dating from the same era, installed to different standards, and modified repeatedly since. The Lisbon apartment inspection guide covers the electrical risks specific to the city's older building stock alongside structural and moisture concerns. In Porto's historic granite construction, electrical installations are frequently embedded in walls with no access or documentation.
Common patterns that create risk in older Portuguese residential stock:
- Electrical boards that predate modern residual current device (RCD/differential) requirements, with no protection against earth faults
- Mixed installations where sections have been upgraded and sections have not, creating inconsistency in protection levels
- Additional circuits added informally over the years without updating the main board capacity
- Aluminium wiring in properties built between the 1960s and 1980s, which ages differently from copper and creates connection risks
- Inadequate earthing (aterramento) in older buildings, particularly in pre-1974 construction None of these problems are visible without testing equipment. They do not appear on any property registration document. They are not verified by the gas inspection (which covers only gas installations), the energy certificate (which evaluates thermal performance, not electrical safety), or any document checked by a notary at the escritura.
What does a pre-purchase electrical inspection assess?
A pre-purchase electrical inspection by an OE-certified InspectOS engineer assesses the electrical installation's compliance with current RTIEBT standards, the condition and protection level of the main distribution board, the adequacy of earthing, the presence and condition of residual current devices, and the overall safety of the installation against the RTIEBT framework.
The assessment covers the complete electrical system of the property:
Main distribution board (quadro elétrico). Condition, labeling, age, type of circuit breakers, presence and rating of residual current devices (diferenciais), adequacy of protection for the number and type of circuits fed. A board with thermal circuit breakers but no residual current differential protection is non-compliant with current RTIEBT requirements and poses a fault risk.
Earthing system (aterramento). Continuity and adequacy of the earthing connection. Inadequate earthing is one of the most common causes of electrocution risk in older Portuguese properties.
Circuit distribution and capacity. Number and type of circuits, wire cross-section adequacy for current loads, evidence of informal additions or bypasses. Additional circuits added to an undersized installation without upgrading the main board are a fire risk.
Visible wiring condition. Condition of visible wiring in kitchens, bathrooms, service areas and accessible ceiling spaces. Damage, deterioration, incorrect routing, and non-compliant installation methods are flagged.
Wet area compliance. Bathrooms and kitchens have specific RTIEBT zone requirements (Zones 0, 1, 2, 3) governing what electrical equipment can be installed and where. Non-compliance in wet areas is frequent in older properties.
Documentation check. Review of any existing electrical documentation — previous inspection declarations, terms of responsibility, or installation certificates. Their absence, for a property above a certain age, is itself a flag.
For buildings constructed before 1983, the electrical assessment should be combined with a structural and seismic inspection guide — seismic damage can affect electrical installation routing and integrity in ways not visible during a standard electrical check.
The InspectOS pre-purchase inspection includes the electrical assessment as part of its 150-point verification. Get a quote for your property at inspectos.pt.
What are the most common electrical problems found in Portuguese properties?
Based on InspectOS pre-purchase inspection findings across Lisbon, Porto and the Algarve, the most frequent electrical issues are absent or inadequate residual current protection, undersized main boards with informal circuit additions, and non-compliant wet area installations.
Absent or inadequate differential protection. Residential installations built before the mandatory introduction of high-sensitivity residual current devices (diferenciais de 30mA) frequently lack this protection entirely, or have a single low-sensitivity differential covering the entire board. Under current RTIEBT requirements, circuits for bathrooms, kitchens and outdoor sockets require dedicated high-sensitivity RCD protection.
Informal additions without board upgrades. Air conditioning units, electric vehicle chargers, heat pumps and additional kitchen appliances have been added to many older installations without upgrading the main board capacity. An overloaded board that trips repeatedly is often the first visible sign of this underlying problem.
Non-compliant bathroom installations. Shaver sockets, heated towel rails, and bathroom lighting fixtures in the wrong RTIEBT zone are common in properties where bathrooms have been refitted by non-certified contractors.
No documented earthing system. Older properties, particularly those built before the 1980s, may have no continuous earthing system linking the board to a proper earth electrode. Visual inspection cannot confirm earthing adequacy — it requires testing.
Aluminium wiring connections. Properties built in the 1960s and 1970s may have aluminium conductors. At connection points between aluminium and copper, galvanic corrosion creates resistance and heat over time. These connections can appear visually intact while posing a fire risk.
Informal modifications and aging systems often coincide with broader maintenance neglect — the mold and damp inspection guide covers moisture defects that frequently appear in the same properties where electrical systems have been compromised over time.
How does the electrical system interact with the buyer's liability under DL 10/2024?
Under DL 10/2024, every deficiency in a property's electrical installation — whether it creates a safety risk, a non-compliance obligation, or a future cost — becomes the buyer's legal responsibility at the moment of signing the deed, with no authority having verified the installation's condition beforehand.
Before DL 10/2024, the licença de utilização that notaries required at the deed gave buyers at least a minimum formal confirmation that the property had been reviewed against building regulations. The electrical installation was not comprehensively checked by this process, but the removal of even that formality in January 2024 means the escritura today is signed with zero public oversight of what the property contains.
For buyers, the consequence is direct. A property with an electrical installation that:
- Has never been inspected since installation in 1978
- Has three informal circuit additions made by the previous owner
- Has no earthing continuity
- Has bathroom sockets in the wrong RTIEBT zone ...is a property whose remediation scope, compliance obligations, and any insurance consequences from electrical incidents all transfer to the new owner at deed signing.
For properties with low energy class ratings, planned electrical system upgrades often form part of the renovation pathway outlined in the EPBD compliance Portugal 2026 guide — buyers should understand both the electrical remediation scope and the broader energy renovation context before committing.
The pre-purchase property inspection covers the electrical assessment as part of its comprehensive 150-point check. For buyers who want to understand the full liability they are taking on before the CPCV, the property inspection before signing the CPCV, the property due diligence guide for Portugal, and the Simplex Urbanístico complete guide cover the legal framework in full.
Before signing the CPCV on a Portuguese property, know what you are committing to. An InspectOS pre-purchase inspection covers the electrical system, structural condition, gas installation, and legal conformity in a single visit — with a bilingual report in 48 hours. Get a quote at inspectos.pt.
Frequently Asked Questions
Is an electrical safety certificate legally required before selling a property in Portugal?
No. For standard residential properties, there is no legal obligation to have the electrical installation inspected before sale. The only electrical certification required in the current framework applies to new or substantially renovated installations at the point of grid connection. An existing residential installation can be decades old, never re-inspected, and the sale proceeds without any authority verifying its condition. This is the protection gap that makes pre-purchase inspection relevant.
Can a gas safety certificate substitute for an electrical safety check?
No. These are entirely separate systems. The gas inspection under DL 97/2017 covers gas installations only — piping, appliances, pressure, combustion ventilation and carbon monoxide risk. It says nothing about the electrical installation. Similarly, the Energy Performance Certificate (EPC) evaluates thermal and energy efficiency, not electrical safety. No single certificate in Portugal covers both gas and electrical systems — they require separate assessments.
What is an EICR, and is there a Portuguese equivalent?
An EICR, Electrical Installation Condition Report, is the UK's periodic inspection report for fixed electrical installations. Portugal has no direct statutory equivalent for existing residential installations. The nearest instruments are the termo de responsabilidade required under the RTIEBT (Portaria n.º 949-A/2006) at the point of a new or substantially modified installation, and the technical assessment carried out as part of a pre-purchase inspection. Neither is a periodic obligation, which is why an installation can run for decades without any authority examining it.
What happens if electrical problems are found during a pre-purchase inspection?
The inspection report documents all findings with photographic evidence. Before the CPCV is signed, the buyer's lawyer can use this documentation to negotiate a price reduction reflecting the cost of remediation, insert a clause requiring the seller to address specific issues before the deed, or include a condition allowing the buyer to exit without forfeiting the deposit. After the CPCV is signed, these options are no longer available in the same form — the buyer is legally committed and any remediation becomes their cost. This is why the inspection must precede the CPCV.
How old does an electrical installation need to be before it's worth surveying?
There is no fixed age threshold. The risk level depends on the combination of installation age, any subsequent modifications, the building type, and how the property has been used. A 1975 installation in a well-maintained property that has never been modified is a different risk profile from a 1998 installation that has had six informal circuit additions. As a general reference: any installation predating mandatory RCD protection requirements, any installation with visible informal additions, and any installation in a property above 30 years old warrants assessment. Given that 68% of buildings in the Lisbon metropolitan area predate the seismic-protection legislation approved in 1958 (Público, February 2023) and were built in the same era as the electrical standards they were installed under, the case for inspection is strong across most of the older housing stock.
Does InspectOS carry out standalone electrical inspections, or only as part of a pre-purchase inspection?
Both. The electrical inspection is included as part of the pre-purchase property inspection, which covers structural, legal conformity, MEP systems and certificates in a single visit. That is the route for buyers, and equally for landlords checking compliance before an Alojamento Local registration, or owners whose installation has not been assessed for a long period. Pricing depends on property type and location, so get an instant quote at inspectos.pt.
Conclusion
Portugal's electrical inspection framework protects new installations through mandatory certification at grid connection. It does not protect buyers from the accumulated history of an existing residential installation. The law is explicit on this point: residential properties are excluded from mandatory periodic inspection under DL 96/2017. What this creates is a systematic gap between what the market sells and what any public authority has verified.
DL 10/2024 made that gap consequential for every buyer. With no verification at the escritura, the electrical system a buyer inherits — whatever its condition — is fully their responsibility from the moment of signing. Foreign buyers, who are often less familiar with the cumulative effect of decades of informal modifications in Portuguese residential stock, should consult the complete guide for foreign buyers for the full verification sequence before committing.
→ Book a pre-purchase inspection — get a quote at inspectos.pt
Updated April 2026 | InspectOS Editorial | InspectOS Portugal
Sources
- Portaria n.º 949-A/2006, de 11 de setembro (RTIEBT), amended by Portaria n.º 252/2015, de 19 de agosto
- Decreto-Lei n.º 96/2017, de 10 de agosto, Art. 4, Art. 8, Art. 19 (electrical installation regime), amended by Lei n.º 61/2018, de 21 de agosto
- Decreto-Lei n.º 10/2024, de 8 de janeiro
- DGEG — Direção-Geral de Energia e Geologia (dgeg.gov.pt)
- IEP — Instituto Eletrotécnico Português, commentary on DL 96/2017 residential inspection gap
- CML/Programa ReSist (seismic building stock data)
- Diário da República, 1.ª série, n.º 154, 10 de agosto de 2017 (primary DL 96/2017 text)