High-voltage power lines near a home in Spain

There is one detail property portals never highlight. It appears in official mapping, it is recorded in electricity company records, and it affects thousands of plots across Spain: proximity to a high-voltage power line.

This is not a technical curiosity. It has three real dimensions that any buyer should understand before signing: legal restrictions on the plot, a possible impact on the home's value, and the issue of electromagnetic fields, which science treats with more nuance than is usually heard in neighbourhood conversations.

What high-voltage power lines actually are

High-voltage power lines are infrastructure designed to transport large quantities of electricity at voltages above 1 kV between generation points and consumption or distribution points. The most visible are overhead lines with their distinctive metal pylons, but there are also underground lines running below ground in urban or peri-urban sections.

In Spain, Royal Decree 223/2008 approves the Regulation on technical conditions and safety guarantees for high-voltage power lines. The transmission grid is operated mainly by Red Electrica de Espana; medium- and low-voltage distribution falls to the regional distribution companies.

The legal dimension: easements that limit what you can do on your plot

Power lines create legal easements over the plots they cross or overfly. These easements are compulsory: they can be imposed even if the owner does not agree, by force of Act 24/2013 on the Electricity Sector.

In practice, this takes two forms:

• Overflight easement (overhead lines) - this includes crossing over the servient land and installing poles, towers or fixed supports to carry the cables, together with the right of access to inspect, maintain and repair the line.
• Underground passage easement (buried lines) - this includes occupation of the subsoil by the conductor cables and the right of access for inspection and repair.

The most important point for a buyer is the no-building strip. For overhead lines, tree planting is restricted and buildings are prohibited within the strip defined by the projection onto the ground of the outer conductors, increased by the regulatory safety distances. For underground lines, construction is likewise prohibited within the strip defined by the trench where the conductors are laid.

If you are buying a building plot or a detached house with a garden and there is an overhead line in the immediate surroundings, this easement may rule out extension plans or make part of the land effectively unbuildable.

The economic dimension: the market already discounts what the buyer does not see

Power lines affect a home's value through three distinct channels:

• Visual impact. High-voltage pylons are permanent, large structures that do not go away. The view from the home is affected indefinitely.
• Risk perception. Whatever science says, there is a social perception of risk associated with power lines, and that affects demand. Better-informed buyers discount the price; less informed buyers may only discover it after signing.
• Restriction on land use. The easement may reduce the plot's real buildability or prevent planned renovations and extensions.

The health dimension: electromagnetic fields, without alarmism but with rigour

High-voltage power lines generate extremely low frequency electromagnetic fields (50 Hz in Europe). These fields have two components: the electric field, generated by the voltage, and the magnetic field, generated by the current flowing through the line. The good news is that they fall away very quickly with distance.

Red Electrica installations record magnetic field values between 1 and 15 uT for 400 kV lines directly beneath the cables. At 100 metres, levels are usually below 0.3 uT. Building materials and trees provide effective shielding, and with buried power lines the fields are barely detectable at the surface.

Are there health risks? The WHO working group has concluded that, in most cases, the scientific evidence supporting a correlation between exposure to 50 Hz magnetic fields and adverse effects is weak. There is, however, one exception treated more cautiously by scientific bodies: the International Agency for Research on Cancer (IARC) classifies these fields as possibly carcinogenic (Group 2B), mainly because of an epidemiological association with childhood leukaemia, although the evidence is not sufficient to establish direct causation.

What Hogarfax analyses

In Hogarfax's Land Uses and Constraints block, we cross-reference the plot's exact cadastral geometry with the power-line layer from the Instituto Geografico Nacional's BTN25 National Topographic Base - Spain's official reference mapping for infrastructure, last updated in December 2025.

The result is not just 'there is a line nearby': we calculate the real distance from the plot boundary to the nearest line, distinguish between high-voltage transmission lines and distribution lines, and indicate whether the plot may be affected by the no-building easement strip.

That information has direct value before any viewing: if you are buying a plot to build on, knowing this may change the project. If you are buying an existing home, it may explain why you cannot carry out the extension you had in mind. And if you have young children and the property is very close to a high-voltage line, it may be a factor in your decision.