ELECTRICAL PLANNING for house in 2024: Complete overview

This raises the big question right at the beginning: What does electrical planning for a well-equipped house in 2024 look like? Why do we need electrical planning? How does electrical planning in new builds today differ from 20 or 30 years ago? What does the electrical planning checklist contain?
Electrical planning or Smart Home electrical planning is an essential part of house construction planning. It is at the beginning of every house construction and follows shortly after the architectural planning. It is important to have manufacturer-independent planning in order to get to know all the technical possibilities and make the house expandable and fit for the future as a networked building.

Comparison of electrical planning today and 15 years ago

Electrical planning has changed significantly over the past 15 years: Today, it touches on all trades of a house – above all the heating system and, if desired, the cooling, the complete lighting indoors and outdoors, the sun protection or shading by means of blinds, shutters or zipscreens, the central ventilation system and the topic of music and podcasts in certain rooms – also known as multi-room audio.

If there is to be a home cinema with a screen and projector or if televisions are to be integrated, then these are also part of the electrical planning. Over the last 15 years, the technical room has become established in new buildings, where all the cables come together in various control cabinets, which we will come to in more detail.

Electrical planning includes the placement of sockets, network sockets, USB sockets, KNX buttons/switches and the installation of safety components such as presence detectors, smoke detectors, water detectors and window or door contacts. It does not matter whether the electrical planning is carried out conventionally or fully networked as KNX electrical planning and equipment as a KNX Smart Home.

The 14 points of perfect (smart home) electrical planning:

Planning the electrical installation conduits – Empty conduits in the building shell
Planning of all sockets, power outlets in floor, wall, ceiling
Planning of all network sockets, WLAN hotspots inside & outside
Planning of all (KNX) sensors such as presence detectors, smoke detectors, water detectors, etc.
Planning of all touch panels and control panels
Lighting design with luminaire positions and luminaire types (DALI, DMX etc.)
Planning multi-room audio with zones and speakers
Planning security technology against burglary (door contacts, window contacts, etc.)
Dimensioning cable types and cable cross-sections
Design of cable lengths
Planning and dimensioning electrical control cabinet/electrical distribution board
Kitchen planning (will be integrated)
Bathroom planning (will be integrated)
Garden and landscape planning (will be integrated)

Lighting design as part of electrical planning

Lighting planning is an essential part of (KNX) electrical planning, which is increasingly being carried out by specialists in high-end house building. Lighting planning involves the specific placement of luminaires in the form of ceiling spots, downlights and LED strips and the selection of the most suitable luminaire types. This is because modern DALI/DMX luminaires are wired differently to conventional luminaires of the past, which could only be “on” and “off”.

Networked DALI/DMX luminaires can display different brightness values as well as different colored light if desired. And who does all this? The electrical planning – in the case of KNX also with KNX circuit diagram – is created by specialized electrical planners with an engineering background. They use CAD software to create and visualize the design before it is implemented in practice by the electrician. The electrical planning contains standardized symbols, which we discuss in full below.

Electrical planning in new buildings: conception and determination of requirements

The technical design of a building is the first step in any electrical planning for a new build. This involves the needs and requirements of the owners and residents: sockets, switches, data and communication interfaces and lighting. Expandability is also important: the electrical installation should also allow for additional devices or systems in the future.

We recommend placing several electrical installation conduits/blank conduits at certain points so that cables can be easily replaced or new ones added later. The concept serves as the basis for the entire planning process.

Below, we also present KNX electrical planning using the example of a detached house. We will start by presenting all the details that are important from the very beginning, shortly after excavation. This applies to both the conventionally wired and the modern networked (KNX Smart Home) new-build house.

The house connection box

In the vast majority of private homes (detached houses, villas, apartment buildings), the domestic connection box is located in the plant room (see blog post). It should at least be planned in there by the architect so that all other technical installations can be bundled together in this room. There are still some architects in Germany who simply forget to plan a plant room! No joke!

The house connection box is mounted on a wall where the house entry or multi-line entry is located nearby. The house entry is a wall penetration that is completely watertight and contains the 400 V power cables (three-phase) and often also the telecommunications cables for the Internet (fiber optic or copper cable). Depending on the design of the electricity grid operator and the region, house connections with 22 kW, 32 kW, 40 kW, 100 kW or 125 kW are possible.

Connected load for a single-family home in Germany

Connected load
New building

22 kW

32 kW

40 kW

50 kW

62 kW

100 kW

125 kW

160 kW

House connection fuse
3-phase

3 x 35 A

3 x 50 A

3 x 63 A

3 x 80 A

3 x 100 A

3 x 160 A

3 x 200 A

3 x 250 A

The table above lists the possible connection capacities for a single-family home in a new build in Germany. Depending on the equipment and size, higher connection capacities are possible. Important: The supply lines are almost always identical in terms of cross-section, the difference is made by the house connection fuses used by the grid operator. In our opinion, 32 kW with 50A fuses is mandatory, more is always better! When using several wallboxes and a larger photovoltaic system, 50 kW with 80A fuses are required.

The ground wire for the house connection

The electrical connection of a house is made via a copper underground cable, also known as a NYY-J underground cable, which very often has the dimensions 4×16 mm2 or 4×25 mm2. The laying of the underground cable is strictly prescribed in Germany both inside and outside a property at a depth of 60 cm to 80 cm below the surface of the ground. After all, the cables should not interfere with other supply lines such as sewage and water.

Very often the telecom cable – more recently as fiber optic cable – is also laid at the same depth.

House entry or multi-line entry?

The building owner or the architect carrying out the work agrees the type of installation of the service pipe with the grid operator company on site.

If buildings are connected underground, the pipes must be sealed to the wall if casing pipes are used. The house entry is made gas and watertight and, if necessary, pressurized water. Coordination of the work across all trades when laying and sealing the pipes is taken into account at an early stage in our planning.

The foundation earth electrode in the floor slab

Every electrical installation in a house needs an earthing system! For this purpose, a foundation earth electrode is installed as a closed ring in the external foundations of every house. In the case of foundation slabs, the foundation earth electrode is installed as a closed ring in the area of the outer walls. The foundation earth electrode must be installed in the floor slab so that it is surrounded by concrete on all sides. This protects it against corrosion and makes it last forever.

The connection parts enable connections to be made to the foundation earth electrode. These include connection lugs and fixed earthing points. The fixed earthing point of the foundation earth electrode must be led out at the house connection wall. The length of the connection lug should be at least 1.5 m from the point of entry into the room. In the case of concrete walls, an earthing fixed point, which is cast into the wall as a connection plate, is best suited for connecting the foundation earth electrode to the electrical system.

The foundation earth electrode is part of every electrical system. The building owner or architect orders the installation during the shell construction phase. This is because the foundation earth electrode must already be included in the tender for the building shell.

The protective equipotential bonding

When building a new house, protective equipotential bonding is required. For this purpose, earthing conductors and metal pipes are connected to the main earthing busbar. This is located in the plant room on the wall with the house connection.

The main earthing busbar in the plant room is the central connection point for the foundation earth electrode, all external conductive parts and the existing PE or PEN conductor. The cross-section of the protective equipotential bonding is based on the cross-section of the largest protective earth conductor in the system. The cables are marked green-yellow.

The technical room

First of all, a few principles that every building owner should adhere to: The plant room must be accessible via generally accessible rooms in the house. It must not serve as a passageway to other rooms and must be located on an external building wall through which the building entry runs.

Our article provides more details on the utility room Planning a utility room in a detached house: What goes in?

The size of the technical room depends on the number of residential units to be supplied and the space required to accommodate technical components such as switch cabinets, components for the heating system, battery storage, inverters of a PV system, ventilation system, etc.

Also to be noted, as there are these regulations: The technical room must be at least 2 m long and 2 m high. The width must be at least 1.5 m if one wall is occupied and at least 1.8 m if opposite walls are occupied.

Electrical control cabinet for a (KNX) detached house

The electrical control cabinet or electrical distribution cabinet can be seen as the technical center and thus as the heart of the electrical system of a single-family home. Its size and dimensions essentially depend on the size and equipment of the house.

For example, a detached house with 600 square meters of living space needs a larger electrical cabinet than a smaller house with 120 square meters of living space. In larger houses, several electrical cabinets are very often used: this saves cable routes and space for cables in the technology shaft.

For some years now, the energy supplier’s electronic meters (electricity meters), including circuit breakers and RCDs, have been housed separately in a smaller cabinet.
Many energy and data bus cables come together in the electrical cabinet.

It must be state of the art and should be dimensioned to provide sufficient space for protective devices, KNX actuators, power supply units and lighting control components such as DALI and DMX, as well as for the PV system, heat pump or a wallbox for charging electric vehicles .

At least 2 switch cabinets in larger houses/villas

For larger houses and villas, our experience in 2024 shows that it makes perfect sense to divide the electrical engineering / electrical distribution boards into different switch cabinets on the individual floors. What are the advantages? Certain areas/floors can be grouped together in one control cabinet. At the same time, the number of cables is limited as not all rooms have to be supplied from a central point.

Electrical installation conduits: Empty conduits for electricity, lighting and network

To ensure that the electrical installation remains up to date for many years to come, electrical installation conduits – also known colloquially as “empty conduits” – should be laid in the walls and ceilings. This allows cables to be replaced and re-routed at any time without the need for time-consuming chiselling work.

Where are electrical conduits absolutely necessary?

Power supply Sockets and wall outlets
Power supply Lighting as DALI or conventional luminaires
Bus cables such as KNX, ModBus, DMX (often laid as hybrid cables)
Door intercom system
Network (LAN) for WLAN hotspots, (KNX) touch panels, video cameras (POE, outdoor area)
Door and window contacts (burglar alarm control panel, alarm system)
Speaker cable for multi-room audio system

In addition, there is the electrical installation pipe/conduit planning for ceilings, walls and outdoor areas in the appropriate dimension – see also our Concept & Smart Home KNX electrical planning.

What options are there if the budget is not sufficient for a complete implementation of all wishes? We recommend installing the electrical installation pipes and associated flush-mounted boxes so that they can be used at a later date. That makes sense!

Electrical conduits for window and door contacts

The pictures below show the details of laying cables for window and door contacts.

Room planning: Room book for room furnishings

The room book defines in detail the room equipment of a house and the outdoor areas such as garage, swimming pool, sauna and garden. The type, number and position of KNX components such as KNX buttons, KNX smoke detectors, KNX humidity detectors, KNX presence detectors, KNX weather stations, KNX status displays and KNX motion detectors are defined.

There are also additional KNX sensors, sockets for indoors and outdoors and KNX touch panels for central or floor-by-floor building control. The room book serves as a basis and template for the entire electrotechnical (building system technology) equipment during the “conception and electrical planning”.

Very important: The best and most suitable KNX components on the market are selected independently of the manufacturer with regard to the best price/performance ratio, functionality and design requirements. A neutral, practice-oriented view of the market is always maintained. Everything needs the corresponding empty conduits: power supply, bus lines, door communication, network, sensors for door and window contacts, warning alarms, etc. Smoke detectors, multi-room audio and COAX satellite cable connection.

There is also empty conduit planning for ceilings, walls and outdoor areas in the appropriate dimensions. Another aspect should not be forgotten when planning the electrical installation. Sometimes a room is to be used differently than originally planned: A bedroom is also to be used as a study in the future. Then, of course, the requirements for the number and positioning of sockets, network sockets and lighting change.

Electrical planning: Standardized signs and symbols

In electrical planning, various signs and symbols are used to represent the electrical elements, sensors, circuits and connections. Here are some of the most important symbols used in electrical planning:

Button/switch: A simple switch is represented by a rectangle with a circle inside. A switch with several positions is represented by a rectangle with several circles. Sockets: A socket is represented by a rectangle with a circle inside. A double socket outlet is represented by two circles.Lamps and luminaires
A lamp is represented by a cross or a circle. A luminaire is represented by a rectangle with a cross or a circle. Junction box: A junction box is represented by a rectangle with a cross. Several cables are connected in the junction box; cables are represented by a solid line. Where two cables cross, the line is interrupted and the two cables cross.

Electrical planning with KNX system, DALI, network

In the future house, the electrical planning including the network is essential for the next steps towards a networked “KNX Smart Home” and, above all, for the implementation by the electrician.

We plan individual detached houses complete with the entire electrical engineering: this includes the number, location, position and types of sensors, sockets, buttons/switches and cameras as well as the most suitable hardware components. The latter come from various manufacturers, as no single company can offer everything and the best products for all areas.

MODULE 1: Our services

✓ Conception of the equipment & functions of the building & outdoor areas
✓ Determination of the room equipment, room book
✓ Cable entry lists for complete electrical installation
✓ Dimensioning of all cable types, boxes and positions, determination of cable quantities
✓ Parts lists for room equipment, electrical control cabinets, cost overview
✓CAD electrical planning across all trades
✓Coordination with HLS/TGA trades