What is it?
AC electric fields are the fields associated with alternating voltages present in installations, wiring and equipment. They exist whenever a conductor is live, even if no current is flowing through it.
They are associated with the alternating current of the mains supply, normally at 50 Hz in Europe. Unlike AC magnetic fields, they do not depend on electricity being consumed: it is enough for the circuit to remain energised. That is why a cable behind a wall can generate a field even when the appliance connected to it is not running.
They form part of the indoor electromagnetic environment and are one of the physical factors covered by the SBM-2024. Studying them does not on its own determine the environmental quality of a building: they are interpreted together with the other physical, chemical and biological parameters. Levels vary from one building to another depending on the installation, the layout of the wiring, the construction materials and the use of the rooms.
Where can it be found?
The usual sources lie in the building’s electrical installation, its wiring and the connected equipment.
In practice: wiring embedded in walls, ceilings and floors, distribution boards, junction boxes, sockets, switches, extension leads, light fittings and appliances connected to the mains. Certain electronic equipment can also contribute and, at times, installations in adjoining homes or premises when they share structural elements.
The assessment pays particular attention to bedrooms, studies and other spaces where people spend long periods. A bed headboard against a wall with a lot of wiring, the location of the distribution board or the presence of permanently powered circuits are situations worth examining specifically.
How is it assessed?
What the inspection looks at
The assessment considers the sources present, their proximity to the areas where people spend time, the spatial distribution of the field, the conditions of use of the space and the scope for technical reduction.
What is recorded for each measurement
Equipment, quantity, unit, location, date, measurement conditions and duration, together with the relevant limitations and the interpretation criterion applied.
How this factor is measured
The technical inspection examines the layout of the rooms, the location of the distribution board, the routing of the wiring and the building’s construction materials.
Measurements are then taken with specialist professional instruments for AC electric fields, following a systematic protocol, at the points where people spend long periods: bedrooms, living rooms and workstations. Where appropriate, body voltage can also be assessed, the operation of automatic demand switches checked, or the behaviour of the installation analysed with different circuits energised.
In assessments intended as expert evidence, calibrated instruments are used to ensure the reliability, repeatability and traceability of the measurements. The data obtained are documented and form part of the technical report.
Criteria
Results are interpreted using the measurement protocol of the SBM-2024 technical standard as a reference. Interpretation is not a matter of comparing a number with a table: it relates the data to the measurement conditions, variability over time, the sources identified and the actual use of the space.
For this factor, the SBM-2024 sets guidance ranges for spaces used for sleeping and for long periods of occupancy, and allows results to be classified according to the degree of deviation observed. The spatial distribution of the field and the construction of the building also bear on that reference.
This guide does not publish values or thresholds. Technical criteria, legal limits and recommendations are different things and are not presented as equivalent.
Improvement measures
Work always begins by understanding and, where possible, reducing the source, before acting on the path or on the space. Measures are prioritised by expected effect, feasibility and proportionality, and no products are recommended by default.
The action taken depends on the origin of the fields detected. Options that may be considered include:
- Rearranging the furniture.
- Changing the position of certain equipment.
- Reviewing the electrical installation and correcting wiring faults.
- Considering the use of automatic demand switches.
- Looking into shielding solutions where they are technically and structurally justified.
There is no universal solution that works for every building. Each recommendation is adapted to the characteristics of the property, the intended use of the rooms and the results obtained, which is why action should not be planned without a prior assessment of the indoor environment.
How Cemprotecta helps
This factor is not assessed on its own. It is measured as part of an assessment that treats the space as a system, because its origin usually lies in the installation and its effect depends on where time is spent.
What an assessment gives you is knowing what is there, where it is and what can be done about it, with an ordered sequence of measures rather than a list of problems.
- Inspection of the space and of accessible installations.
- Measurement in the rooms where people spend most time.
- Combined interpretation with the other factors assessed.
- A report with measures ranked by their expected effect on exposure.
Request an assessment
If this factor concerns you in your home or workplace, tell us about your case. The prior inspection will determine whether it is worth measuring and what else should be assessed alongside it.