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Lay the power cable in the house
Lay the power cable in the house

Video: Lay the power cable in the house

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Video: How to Lay Electrical Cable Underground | This Old House 2023, February

It is better to relocate power cables in old houses. Security standards have changed a lot since the 1950s. Here, we explain what needs to be considered when laying cables.

Check the cables

Many who build for the first time later find out what they have forgotten when planning the electrical installation. Often there are too few sockets for mixers, coffee machines, microwaves, TVs and satellite receivers, DVD players, computers and Internet radio and, moreover, in the wrong place. In addition, intelligent devices such as smartphones or tablet computers should be connected to the Internet, heating or roller shutter controls and smoke detectors. The necessary network connections are often missing here. Some rooms are used differently later, for example when the children are out of the house. The electrical renovation of an old building is a chance to learn from old mistakes and to do everything better this time. Subsequent electrical installations are many times more expensive.

In recent years, many sensible standards have been established that have made our home more comfortable, but also much safer from all kinds of electrical accidents. Modern automatic circuit breakers switch off the power immediately when overloaded and prevent smoldering fires in power cables. So-called residual current circuit breakers (RCD, from English R esidual C urrent D evice) protect the life and limb of the residents. They react instantly to overvoltage or fault currents, such as when a child pokes the socket with a paper clip. Such switches are mandatory today, especially in damp rooms such as bathrooms. Also for outdoor sockets in the garden. In any case, they are also useful for the washing machine basement, but best for every floor in the house. There was no such thing 50 years ago.

When you take a look at your inherited or purchase property for the first time, take a close look at the existing electrical infrastructure. The external appearance of the house connection and fuse box gives a first impression of the overall care status. If you already recognize brittle cables and bare wires, this usually allows conclusions to be drawn about all existing electrical lines. Electrical cables age in 30 to 35 years - even faster if they are frequently overloaded and thus heated. Multiple socket strips, for example, are often the culprits because they replace non-existent sockets and can overload main power connections. The current distribution in the fuse box reveals, if there is one, how many circuits exist. In the early days, three circuits were often sufficient: for the stove, sockets and light. Each of them may still be equipped with an old fuse, which should blow out and be replaced if necessary. Today, residential buildings are divided into many different circuits, because this avoids a high permanent load and if one circuit fails, the whole house does not go dark.

alte Schalttafel
alte Schalttafel

Security standards have improved since the 1950s.

Photo: MEV

Laying the power cable: It is best to hire an electrician

Generously dimensioned power lines quickly pay off because they save electricity: thicker lines have less power loss than thinner ones. If you overload old power cables, there is a permanent fire hazard. Old installations are often only protected with a few amps, for example with six amps. Today, 16 amperes and more are standard, so that the washing machine and dryer run uninterrupted. The existing power cables must be dimensioned for this, i.e. they must have an adequate cable cross-section. Be careful: The color scheme for phase (black), neutral conductor (blue) and protective conductor (green-yellow), which is mandatory today, has not yet been used for older cabling. Power lines without a protective conductor have been banned for new installations since 1973, but are still frequently encountered in the context of existing protection. If you want to replace the wiring anyway due to undersizing, it is three-wire with protective conductor for sockets and light and five-wire for stove connections (three-phase current).

If you now commission an electrician to carry out the renovation measures, the RAL-RG 678 (plus) standard provides initial guidance on which measures have to be taken for the rewiring. So how many sockets and light connections in which rooms, how many and which installation pipes, light switches or dimmers, cookers, data and telephone connections. Their division into star classes (the more stars, the better) helps you for the first conversation with the electrician and the comparability of various offers, which are usually made according to this RAL standard. However, before such a conversation, you should deal with the planned electrical equipment of your home yourself - after all, it should also fulfill all your individual wishes. If ceilings and walls are already slit open, enough empty pipes should be installed so that you can also lay more power cables or data cables later. Upon request, the electrician will tell you which wall passages, wall slots or holes for junction boxes and device boxes you can make yourself in order to save costs. For slits, the wall thickness must be taken into account: Thin walls do not allow thick cable ducts without which the statics of the wall are endangered. Once lines and pipes have been laid, you can plaster or fill yourself. Depending on whether the walls should be painted or wallpapered.

Kabel verlegen
Kabel verlegen

Be clear about your individual wishes in the electrical installation before you hire an electrician.

Photo: MEV

Certain rules apply when laying cables

Power lines must be laid separately from data, control (EIB or KNX bus) and telephone lines in separate empty pipes. The minimum distance between power and data cables continues to depend on their shielding and any built-in separators made of aluminum or steel. The electrician can tell you exactly in your specific case. Power cables can interfere with data, TV and telephone transmission if these distances are not observed. In order to contain electrosmog, power and data cables with special shielding are used, which, however, are significantly more expensive. If there is sufficient sensitivity, do not use wireless DECT telephones or WLAN for the Internet and prefer to lay the appropriate network cables. They have significantly fewer emissions and do not require their own power supply.

Power cables are available either as round cables or flat cables, which are easier to lay, but are only used in dry rooms. The cables are always to be laid vertically or horizontally in the wall, so that they are easier to find later under plaster and not unpleasantly surprised when hanging pictures. Only diagonal cable feeds are permitted in the ceiling. The distances for laying cables in living rooms are also mandatory: 30 centimeters from the ceiling and floor, 15 centimeters for door frames, corners and windows. In the bathroom, special provisions apply for clearances to wash basins or shower basins.

Planning the networking

With so-called powerline adapters, you can establish the desired connections via the existing power lines. Appropriate adapters are simply plugged into the socket and transmit Internet, photos or entire films, for example from the computer to the television. Communication systems via the power line work best if they are on the same power phase. A phase coupler in the fuse cabinet can be helpful.

If you have many radiators in different rooms, you can also use a wireless control to connect the central thermostat to the control units screwed onto the radiator. The central programming ensures that the bathroom is nice and warm in the morning and evening, but is turned down during the day. The bedroom is only heated at night and the temperature is reduced during the day. Such an individual and automatic control is practical, saves energy and frees you from the daily radiator runout. Smoke or other hazard detectors can also be wirelessly networked in battery mode; the alarm of a detector is triggered anywhere in the home. These technologies are particularly useful for renovations if the entire power cabling does not have to be replaced. Otherwise, you should always prefer the laying of data cables over the wireless version, because electrosmog and power consumption are reduced.

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