Did you know that a renovation should involve more than replacing furniture?

An electrical wiring renovation should comply with the applicable technical standards and national and international regulations. Electrical installations for various uses (residential, services, industry) are governed by the Technical Rules for Low-Voltage Electrical Installations (RTIEBT), regulated by Ordinance no. 949-A/2006.

More recently, Decree-Law no. 96/2017 establishes the rules for medium-, high- or low-voltage private service electrical installations supplied by the public service power grid (RESP), as well as for temporary or mobile electricity-generating installations for safety or emergency purposes, further defining a system for controlling, supervising, and regulating the activities associated with these.

In addition to the aforementioned regulations, we should highlight the following:

  • Regulatory Decree no. 90/84 (namely for closed condominiums);
  • Decree-Law no. 90/2014, CTE 64, and Ordinances no. 252/2015 and 221/2016 (for installations with electric vehicles);

By way of example, we refer some aspects that should be taken into account while renovating a residential electrical installation:

  • The earthing system should be carefully planned in order to obtain an appropriate value to ensure that the touch voltage is lower than the limit safety voltage and that the differential protections have suitable dimensions.
  • Sometimes there is the need to ensure the automatic cut-off of the supply by means of a circuit breaker with a differential current lower than or equal to 30 mA.
  • Earth conductors should be well connected and all the components of the electrical installation liable to be in contact with the soil should have an earth connection.
  • Electrical networks should be separated from non-electrical networks.
  • All equipment installed in areas with showers, bathtubs, or swimming pools should be subject to more stringent protective measures.
  • Switchboards should have the appropriate protection indexes (IP, IK) to guarantee safety with regard to access and use, with the appropriate earth connections.


André Sá
Engenheiro Eletrotécnico (sistemas de energia), Mestre e Especialista