How many light points and sockets does each room need?

Before quoting a home's accessories you have to decide, point by point, from how many places each light will be switched on and what amperage each socket needs. They are details that seem minor until a wall has to be chased to add a point that was forgotten.

Light point: not all are operated the same way

• Single (1 switch): switched on and off from a single switch.
• Two-way (2 switches): lets it be switched on from two different places — the typical case is a bedroom (entrance and bedside) or a staircase.
• Intermediate (3+ switches): combined with two-way switches to operate the same light from three or more points, usual in long corridors with several accesses.

Deciding this before opening chases avoids having to add a third cable afterwards.

Sockets: the amperage depends on what will be plugged in

A standard schuko socket outlet covers 16A, enough for most domestic outlets. For the kitchen, washing machine, tumble dryer or any high-consumption appliance, you need to go up to 25A. Confusing this isn't just a performance problem: an undersized socket under continuous load heats up more than it should.

Switches: four types depending on where they're needed

• Single: on/off from one point.
• Two-way: from two.
• Intermediate: combined with two-way switches for three or more points.
• Timed: switches off by itself after a time — typical on staircases and communal entrances.

Special outlets: industrial, data and dimming

• Industrial socket (CETAC): the number of poles indicates the conductors — 2P+E is single-phase without neutral, 3P+N+E full three-phase, 3P+E three-phase without neutral. Always match the amperage (16A, 32A or 63A) to the real load of the equipment to be connected, never the other way round.
• Data outlet: RJ45 Cat.6 is the current standard for networking, with capacity up to 10 Gbps over short runs; coaxial is kept for television (aerial or fibre with converter).
• Dimmer: not all are compatible with any load — universal dimmers accept LED, halogen and incandescent, but some dimmable LEDs need a specific dimmer to avoid flicker.

Frequently asked questions

What's the difference between a two-way point and an intermediate one? The two-way is operated from 2 points; the intermediate is combined with two-way switches to reach 3 or more operating points on the same light.

When do I need a 25A socket instead of 16A? For the kitchen, oven, washing machine, tumble dryer or any high-consumption appliance that explicitly requires it in its data sheet.

Which data outlet do I choose for wired internet? RJ45 Cat.6, the current standard, with capacity of up to 10 Gbps over short runs.

Conclusion

Defining the operating type of each light point and the real amperage of each socket before starting the installation is what avoids having to open the wall again to add a missing cable. Quoting by accessory, not as a generic "electrical" item, makes clear to the client exactly what they are paying for in each room.