Electrical installation design for a family house: what it includes, when you need it and what drives the price

28 October 2026 · 5 min read

The building authority, the grid operator and the inspector all ask for the electrical design. What it must contain so the electrician can build without guesswork, and what drives its price.

When you need an electrical installation design

For a family house, the electrical design comes up in four situations:

Building permit – the permit documentation under Czech Decree No. 131/2024 Coll. includes an electrical part: a technical report, a basic diagram and a site plan with the service connection. Without it the authority will not accept the documentation as complete.
Grid connection – the grid operator (EG.D, ČEZ Distribuce, PREdistribuce) requires the meter cabinet and the service connection to follow its connection conditions; the design proves this and the installer builds from it.
Installation and inspection – the electrician needs to know where the switchboards, circuits, sockets, lights and cable routes go; the inspector checks the installation against the documentation. Without a design the inspection ends with reservations, or the documentation is drawn up “as built” afterwards.
Solar PV, battery, EV charging, heat pump – each of these needs spare space in the switchboard, correct protection and often a change of the main circuit breaker or the service connection. Planning it in advance is far cheaper than retrofitting.

The electrical design for a house is also needed in a renovation: when the switchboard is replaced, circuits are added or the house is connected at a higher capacity, the grid operator and the inspector want the documentation just as for a new build.

What the design for a family house contains

Part	What it contains
Technical report	Description of the solution, supply system, protection against electric shock, list of circuits, standards applied, grid operator's conditions, requirements for installation and inspection.
External influences report	Which rooms are ordinary and which are damp or outdoor (bathroom, garage, terrace) – this determines the protection rating of equipment and the installation method.
Power layouts	Each floor: sockets, switches, lighting points, fixed appliances (cooker, oven, pump, air conditioning), switchboards, cable routes, circuit labels.
Low-current layouts	Data outlets and routes, TV distribution, doorbell, preparation for alarm and cameras, home control system if you want one.
Switchboard diagram	Single-line diagram of the house switchboard: main breaker, residual current devices, circuit breakers, surge protection, contactors for the heat pump or water heater, spare space for PV and an EV charger. We prepare it so that a switchboard manufacturer can price it directly.
Meter cabinet and service connection	According to the grid operator's connection conditions: location at the plot boundary or in the fence, main breaker, supply into the house, earthing.
Calculations	Total demand and diversity, sizing of cables and protection, voltage drops, verification of disconnection by the protective device.
Lightning protection and earthing	Risk assessment and LPS design, foundation earth electrode, surge protection – details in the article on the lightning protection design.
Bill of quantities	List of materials and works for tendering electricians – the quotes are then comparable.

The scope depends on the stage: the permit documentation is shorter (technical report, diagram, site plan), the detailed design contains everything above and the as-built documentation records how the house was finally wired.

What we pay attention to

Numbers and positions – the Czech standard for indoor wiring (ČSN 33 2130) sets minimum numbers of sockets and lighting points by room type and their mounting heights; the design follows it but starts from how you will actually use the house – kitchen worktop, study, garden.
Bathrooms and outdoor areas – bathroom zones, protection ratings, residual current devices; outdoor sockets and lighting, supply for a pool or a garden shed.
Spare capacity – space in the switchboard, conduits for future PV and a battery, a cable to the EV charging point, a supply for the heat pump. Today it costs a few metres of conduit, later it means chasing walls.
Coordination – with the building design (openings, chases), heating, ventilation and with the architect on visible elements (luminaires, switches).
Manufacturer independence – switchboard devices and luminaires are specified by parameters; the owner chooses the brand with the electrician, so the electricians' quotes are comparable.

What drives the price of the design

House size and number of floors – more rooms mean more circuits, sockets and drawings.
Design stage – permit only, or also the detailed design and the as-built documentation.
Technology – heat pump, PV with a battery, EV charging, heat recovery ventilation, smart home – each adds circuits, calculations and coordination.
Low-current systems – basic data outlets only, or a complete design of the network, alarm and control system.
Lightning protection – part of the house design, or separately.
Input documents – DWG floor plans from the building designer shorten the work; renovations without documentation require a survey of the existing state.

We set a fixed price after receiving the floor plans and your idea of the technology. A price per square metre, which some people search for, makes no sense for a design: two houses of the same size with different technology are a different amount of work. More about the whole service on the electrical installation design page.

What we need from you

floor plans and sections of the house (ideally DWG, PDF is fine too), a site plan with the plot and the connection point,
a list of technologies: heating, hot water, air conditioning, PV, EV charging, pool, garden buildings,
your idea of how the rooms will be used (study, kitchen worktop, workshop) – the circuits and sockets follow from it,
for the grid connection the existing contract or the grid operator's statement, if they already exist.

Frequently asked questions

Do I need an electrical design for a flat as well?

For a renovation with a new switchboard and new circuits, yes – the inspector and the building manager require it. The scope is smaller than for a house: a layout, a switchboard diagram and a technical report.

Is a template electrical design in PDF from the internet enough?

As an idea of what the documentation contains, yes. As the documentation for your house, no – the number of circuits, the protection, the voltage drops and the grid operator's connection conditions apply to a specific house and place.

Do you also design solar PV on the house?

Yes, either as part of the electrical design (preparation and spare capacity) or as a separate PV design including the grid connection – see solar power plants.

How long does the design take?

It depends on the design stage, the extent of the technology and the completeness of the input documents; for an ordinary house it is a matter of days to weeks. We agree the deadline at the start.

Planning a similar project?

Send us the site and your intent. We reply within 48 hours.

Request a design