3.45, 4.6 or 6.9 kVA? Choosing Electricity Power in Portugal

Your bill measures the electricity you use in kilowatt-hours, or kWh. Contracted power is the limit on how much can be drawn at once. To estimate that demand, add the watt ratings on the appliances running together. The total is approximate because motors and other equipment can draw extra power when starting.

For example, a 2,000 W kettle, a 2,000 W heater and 300 W of background equipment add up to 4,300 W. A 3.45 kVA contract is unlikely to accommodate that combination. Turning off the heater while the kettle boils changes the calculation.

ERSE lists 13 normal low-voltage levels: 1.15, 2.3, 3.45, 4.6, 5.75, 6.9, 10.35, 13.8, 17.25, 20.7, 27.6, 34.5 and 41.4 kVA. Your installation’s authorised maximum determines which of these you can request.

The calculator adds the electrical input of the appliances you select, then shows the next single-phase contract level above that total. A second result adds 15% spare capacity to illustrate the effect of a margin. Use the ratings on your own equipment when comparing the two.

With three-phase supply, the distribution of appliances across phases matters. A 6.9 kVA total can correspond to 2.3 kVA per phase. ERSE notes that some network arrangements allow different monitoring of total power. Ask the network operator how your installation is controlled. Adding all appliance loads without checking their phases can give a misleading answer.

Smart meters can enforce the contracted limit more accurately than an older limiter. A combination that previously worked may now trip the supply. Repeated tripping can also indicate an electrical fault. If one circuit trips or wiring becomes hot, ask a qualified electrician to investigate rather than simply increasing contracted power.

EV charging can dominate the total. ERSE gives 2.3 and 3.7 kW as examples of slow charging. Check the charger's actual setting. Charging overnight, delaying the water heater or using properly configured load management may avoid a larger contract. A three-phase charger needs a phase-aware assessment.

For other equipment with high demand, check the following ratings.

The bill includes a fixed power charge, normally expressed in euros per day. The amount depends on the supplier's offer and regulated network charges. A higher level can also affect the energy price or other contract conditions. Compare the whole offer using ERSE's price simulator.

To compare offers, multiply the difference in their daily charges by the number of days. For example, an extra €0.10 a day adds €36.50 before tax over 365 days. Also check social-tariff eligibility before moving above 6.9 kVA, its contracted-power ceiling.

Contact your electricity supplier. ERSE says the contractual change is free and has no limit on the number of requests. An integrated smart meter can usually be changed remotely. Other meters may require a visit. A missed appointment can have a charge.

A request above the installation's authorised capacity may require technical work and certification. Those costs are separate from the free contractual change. Confirm the available capacity, any installation work and the new tariff before accepting.