Field reduction in new construction
Here all options are open. We recommend the use of shielded cables and shielded switch boxes. The principle of field reduction is based on the envelope of the three-core cable with a conductive aluminum foil, and the entrainment of an additional wire, which is in contact with the aluminum foil. The drain wire and the earth are brought together in the switch box and connected to the potential equalization. Shielded plugs are especially recommended in quiet areas of the house, eg in the bedroom and children’s room or at the reading corner in the living room. In wooden houses sockets should be seamlessly integrated into the shielding concept. It is recommended to ground the switch also. The additional costs are roughly 3,000 EUR to quote for a house with 130 m2 of living space.
Field reduction in existing dwellings
The quality of the electrical installation can be very different depending on the year of the house. By the end of 1980, bar lines were used. The unfavorable arrangement of the lines high field strengths generated which is transferred through the walls and ceiling to other floors. Also unshielded standard cables generate electric fields on the upper floor, when they were transferred directly into the ceiling. Ideally, a replacement of obsolete lines through shielded cables is possible when the line bays are easily accessible. Otherwise, leaving only the shutdown of individual circuits during the night for residents. This can be done manually by the respective fuse switch is actuated, or more elegantly, by the incorporation of demand switches. If the mains isolation switch is supposed to work, no electricity consumers may be active on the circuit.
Network shutdown does not always work optimally
The use of demand switches can bring in the coexistence of residents problems. For example, out of the apartment in the basement of an electric field is transferred to the children’s room upstairs. The children go to bed at 19 clock, the adults in the basement until about 24 clock. Then the children are exposed despite demand switches for half of the night’s sleep the electric field.
First test – then shut off circuits
As mentioned above, an electric field from neighboring rooms or floors can be transferred. Then it is not sufficient to turn off only the power circuit of the actual sleeping space. There are to identify further field loads. This can only be done properly by the application of a floating three-dimensional field strength measurement. Most electricians do not have this equipment. Therefore, a building biologist should be consulted. Together with the residents can then be checked one circuit after the other.
Floor and wall shield
If the installation of demand switches from pressures of living together out of the question or is produced the electric field in the neighboring apartment, then it is possible to selectively shield walls or floors over a large area. Suitable material can now be purchased from several suppliers in Europe. There are used, for example, colors for shielding the wall or webs and copper mesh for floors and ceilings. Before attaching the shield must be checked whether the grounding of the material is practically feasible. The electrician is required to connect the shielding to ground. The shield must be checked before and after by the building biologist with a measuring.
Building Biology Evaluation Guidelines for low-frequency electrical fields
The following values for the assessment of electric field strength are (potential-free measuring / unit is volts per meter):
10 Extreme Concern
In measurement practice of building biologists field strengths of greater than 10 volts / meter are not uncommon. It is then necessary to search intensively for reduction opportunities.
General tips for field reduction
Regardless of the type of installation and the use of demand switches some ways can be used in everyday life in order to avoid low-frequency fields:
• pulling out plugs of electrical appliances from the socket
• Use of switch panel or adapter plugs
• Maintain a distance of radio alarm clocks and charging stations
• Maintain a distance of bedside table and desk lamps
• Use an external keyboard at work on the laptop
More information on the German website:
picture source: http://cloud.danell.de/2.%20Produktbilder/2.1%20Installationskabel/