1. Electrical installations - what do you need to know?

Electrical installations are now an important part of the urban environment. They provide access to drinking water, the drainage of wastewater, lighting, heating, cooling, the operation of various electrical equipment, and appliances for households and industry. An installation system that is professionally designed and fitted and powerful enough enables the smooth functioning of community life. Residential electrical installations are part of this huge system and, as with other jobs, their installation requires high levels of expertise and experience. However, it is still a good idea for any homeowner to know something about the basic concepts and techniques as it will make it easier to negotiate and agree with the designer and contractor should you ever need their services.

1.1. Measuring and maintaining electrical installations

The condition of residential wiring, devices, and electrical equipment should be checked at least every 10 years, i.e. testing the voltage and conductivity of the electrical supply. In this way, the electrician performing these checks can determine whether there are any problems with the electrical supply itself or with a piece of equipment. If not detected early, these problems can lead to short circuits and electrical shocks, but also fire. While he’s at it, the electrician should also check both the lightning protection system and computer installations. An electrical safety certificate can then be issued showing that your property is safe. Lightning conductors should be checked every 2-4 years and must be checked after lightning strikes. Installations are also inspected thoroughly before carrying out any major work, such as renovations. If you check the installations regularly and maintain them according to the instructions (testing the voltage, repairs when necessary, fuse replacement, etc.), you won’t experience a break in the power supply that can damage electrical devices even during electrical storms. 

2. Professional design and installation

It is always a good idea to make a detailed plan before the work is carried out; in this case, an electrical engineer or an experienced electrician can draw up appropriate plans for a house or flat. Low-voltage wiring is used for lighting and household appliances, while telecommunication cables are used for telephones, computers, air conditioners, intercoms, and protection against fire and burglary. The design and installation of electrical wiring and cables requires a competent professional with experience. We advise you against doing this kind of work yourself under any circumstances. There are numerous legal and professional requirements that must be strictly adhered to when designing and installing such a system to make sure it is safe and easily accessible in any situation.

3. Types of installations

3.1. Low-voltage electrical and telecommunication installations

Lighting and household appliances are powered by low voltage wiring. Phones, computers, air conditioners, intercoms, and protection against fire and burglary are powered by telecommunication cables.

3.2. According to the method of installation

Wires and cables can be installed in different ways:

- beneath or into a layer of cement mortar: the wiring is placed against the bare wall and then plastered over;

- over plaster: this is how wiring is fitted in rooms with plumbing, mounted with plastic conduits and appropriate fastening straps;

- into hollow walls: installations can be flammable or non-flammable and this affects what kind of material will be used for dry construction;

- into concrete: the same as for wiring installed beneath or into a layer of cement mortar, installed during the roughing-in phase of construction work;

- into installation ducts: this is how electrical installations are fitted mainly in industrial facilities and very rarely in residential buildings;

- with uninsulated conductors: only for low voltage systems, e.g. halogen lights and similar appliances and devices.

It is very important that electrical installations are fitted according to the agreed plan and building regulations. Low-voltage and high-voltage fuses must be at least 5 cm apart. They must also not be in the same electrical circuit unless separated by a partition wall. Electrical cables are routed through plastic conduits, allowing for easier repairs and replacement at a later date. It is important that all electrical connections are protected via the third (‘earth’) conductor in a three-wire cable.

4. Installation procedures for residential properties

4.1. Installation

It is crucial that electrical installations are planned in detail, carefully and professionally, as it is the only way to avoid possible complications later on. If, for example, the bathroom is being renovated, the ceramic tiles must be smashed and removed in order to get to and replace the wiring. The fitting of electrical installations takes place in two phases. The first is during the rough-in stage, while the second phase is concurrent with other interior and exterior finishing work. The electrical rough-in starts when the partition walls are finished. It is also the time when the other various mechanical and plumbing lines are brought in, as well as the telecommunication cables. If the walls are masonry walls, the electrical cables are laid in pipes before or during plastering, and if the walls are made of plasterboard, then the cables can be run through them, since they have cavities. For new builds, electrical installations are laid directly into the concrete slab. PVC pipes are placed on the formwork immediately before pouring the concrete and it is vital that they are not damaged. This way, recesses don’t have to be cut into the finished walls. The electrician runs the cables through these pipes and, later, when there is a fault or a need to replace something, they are easily accessible. Installation pipes are always installed horizontally and vertically, and never diagonally, at a height of between 20 and 120 cm from the floor, in order to make repairs or retrofitting easier later on. Only on the ceiling are the pipes laid across the shortest possible distance. On average, a family home requires 500-1000 m of cables and 10-15 junction boxes.

In a residential electrical system, there may be an increase in electrical resistance in the conductors and, consequently, a decrease in their insulation. When installing new wiring, there may be a failure to connect the wires correctly. In order to prevent damage from electric shocks and short circuits, which can even lead to fire, precautions must be taken. Sockets in the kitchen must therefore be placed at least 1 m above or below and 50 cm to the left or right of plumbing fixtures. The same is true for the bathroom. If the sockets have protective covers or if a device is always plugged in (for example, a refrigerator, dishwasher, etc.), this gap can be reduced to 30 cm. In bathrooms and other rooms with plumbing where the risk of electric shocks is always higher, all appliances must be run through a 0.03A RCD or through a 0.03A safety switch. Such switches must always be located outside the room. The use of safety covers is also recommended for sockets in children’s bedrooms, as well as in the living room.

4.2. Connecting to the distribution network

1. When the preliminary residential wiring plan has been drawn up, you need to submit an application to be connected to the distribution network. Approval can be given to a householder or a business.

2. Connections can be permanent or temporary, individual or group, and in this sense applications are divided into two types: applications for power up to 43.5 kW and over 43.5 W or applications to connect a building which is seeking retroactive planning permission. 

3. The application should contain the following documents:

- planning permission for the building which is to be connected,

- confirmation from the appropriate authority,

- proof of ownership or right of use,

- a 1:500 (1:1000) situation plan drawn on a copy of the plan, no more than 6 months old, 

- proof of payment of administrative fees.

4. If approved, the Distribution Network Operator issues a document giving approval for the connection, and once a contract for the provision of electrical energy has been signed with the DNO, it is legally obliged to connect the building to the main network within 15 days if all legal and technical prerequisites have been met.

5. Prior to being connected, a contract setting out the terms for providing the connection to the electricity distribution network also needs to be signed. The final contract is one for the provision of electrical energy, and then finally you will be connected to the distribution network.