How much electrical power do you need to contract?
Tick the appliances you have at home and we tell you how much power to contract (in kW) so you neither overpay nor fall short. No sign-up.
We apply a 55% simultaneity factor: not all appliances run at the same time.
Indicative estimate: the sum of typical appliance powers multiplied by a simultaneity factor and rounded up to the standardised contractable power tier (3.45 · 4.6 · 5.75 · 6.9 · 8.05 · 9.2 · 11.5 kW). The real optimal power depends on your habits and your installation; we fine-tune it during a visit.
How much electrical power to contract at home
Your contracted power (in kW) sets how much electricity you can use at once before the RCD or the ICP trips. Contract too much and you pay an unnecessary fixed charge every month; contract too little and the power cuts out when several powerful appliances run together. The sweet spot is adding up the power of what you own and applying a simultaneity factor, because everything almost never runs at once.
Our calculator adds the typical power of each appliance you tick, applies a simultaneity factor of around 55% and rounds up to the next standardised contractable power tier (3.45; 4.6; 5.75; 6.9; 8.05; 9.2 or 11.5 kW). Appliances such as induction hobs, ovens, air conditioning, heat pumps or EV chargers are the ones that push the required power up the most. If you change your contracted power you will normally need a valid electrical certificate (CIE).
What affects the power you need
- Induction or ceramic hob: one of the biggest single loads (~3.5 kW) and a heavy factor in the calculation.
- Air conditioning and heat pumps: they add power when running, especially at the same time as the kitchen.
- EV charger: 3.7 to 7.4 kW; it usually forces a tier up if you charge at home.
- Simultaneity: the more your usage overlaps (cooking while washing and cooling), the more power you need.
- Electrical certificate: increasing power beyond what your installation allows usually requires a CIE from a licensed installer.
Frequently asked questions about contracted power
How much power do I need to contract at home?+
It depends on which appliances you own and how many you use at once. You add up each appliance's power and apply a simultaneity factor (around 55%), because everything almost never runs at the same time; the result is rounded up to the next standardised tier. A normal flat usually sits between 3.45 and 5.75 kW, more if there is induction cooking, air conditioning, a heat pump or an EV charger.
Why does the RCD or ICP trip?+
It trips when the power you are using at once exceeds what you have contracted: for example, running the oven, the induction hob and the air conditioning at the same time. If it happens often, it is a sign you are short of power and should go up one tier. The calculator warns you when your demand is very close to the recommended tier's limit.
Can I increase my contracted power?+
Yes. You can change your contracted power with your supplier, and to increase it your installation usually needs to support it and a valid electrical certificate (CIE) must be filed. We check your panel, verify how much power your installation allows and process the certificate if needed.
Do I need an electrical certificate to change my power?+
To increase the power beyond what your installation was registered for, the grid operator normally requires an Electrical Installation Certificate (boletín/CIE) issued by a licensed installer. Reducing power usually does not require one. We assess your specific case and issue the certificate if you need it.