Electrical installations and switchboards

In a new build we carry out the installation from the design: conduit, cables, wiring accessories, switchboard and earthing. In a refurbishment the first step is to know what is there. Some installations need only a new switchboard and two or three circuits; others call for cables and protection to be replaced, in stages. We tell you which case is yours before proposing any work, with a diagnosis and a budget estimate.

We also install lighting and the supply to equipment, including EV chargers.

The switchboard (quadro elétrico; a British electrician would say consumer unit) is where the installation is protected and where you can tell, or not, what each circuit feeds. Inside switchboards we fit Schneider Electric and Hager devices. In a board built by us you will find:

• Circuit breakers (disjuntores), one per circuit, which cut off on overload or short circuit. In homes, the Portuguese wiring rules (RTIEBT) require this protection to be by circuit breaker.
• Residual-current devices (interruptores diferenciais), which cut off when current leaks to earth. High-sensitivity ones (30 mA) are recognised by the rules as additional protection against electric shock. We spread the circuits across several of them, so that a fault in one appliance does not leave the whole house without power.
• A surge protection device (descarregador de sobretensões), which diverts to earth the voltage spikes arriving from the grid, for example during thunderstorms. The rules recommend one at the origin of the installation when the supply arrives by overhead line.
• Labelled circuits, with labels that match the switchboard diagram. That is what lets any technician, ten years from now, know what is being switched off.

Contracted power (potência contratada) is the limit on how much power you can draw at once; go over it and the supply cuts out until you reduce the load. Three parties are involved in an increase:

• Your supplier (comercializador), the company you pay for electricity, takes the request when the power you want is below the maximum admissible power of the installation.
• E-REDES, the distribution network operator, takes a grid connection request when the power you want is above that maximum. That request needs a ficha eletrotécnica, a technical form on a DGEG model.
• The installer checks, before the request, whether the installation can carry the new power (incoming cable, switchboard, protection), makes the necessary changes and prepares the ficha eletrotécnica when it is asked for.

If you do not know what that maximum is, start with your supplier. And before asking for more power, confirm that you really need it: measuring consumption settles the question.

The most common contracted power levels, 3.45 and 6.9 kVA, fit a single-phase supply. The wiring rules say that installations with no three-phase equipment and up to 10.35 kVA are to be single-phase; above 10.35 kVA the supply has to be three-phase (trifásico). Three-phase is also justified when there is three-phase equipment, such as chargers of 11 kW or more. The change affects the grid connection, the switchboard and the distribution of circuits across the three phases; we assess first whether it is worth it.

A tested, working installation, a switchboard with labelled circuits and its diagram, and the execution documents. Once the work is finished, Decreto-Lei 96/2017 provides that whoever carried it out performs the tests and checks and issues the declaration of conformity of execution or the execution responsibility statement (termo de responsabilidade pela execução). In a home of up to 6.90 kVA, that document allows the installation to be connected to the grid; above that, the law also asks for an inspection declaration, issued by an electrical installation inspection body (EIIEL). What applies to each job is confirmed at the outset.

• The type of property and of work (new, full refurbishment, switchboard only) and the town.
• Photographs of the switchboard, with its door open, and of the meter.
• The contracted power, which is on your electricity bill.
• The floor plans, if there are any.