Power networks/Guidelines/Power lines

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This page is under construction.

Power lines are essential parts of the energy network, carrying electricity from generation sites (power plants) to end users (homes, businesses, industries). Mapping them shows how electricity is distributed and supports uses like planning, emergency response, and data analysis.

Accurate mapping and tagging of power lines helps build an open, global view of electricity networks that is essential for understanding energy access, identifying gaps in connectivity, and supporting energy transition.

This page aims to offer clear guidelines on how to map and tag power lines. It’s designed for all mappers, including those with no technical background in energy.

Power lines pose serious safety risks, including electric shock and electrocution, that may lead to death.

All information gathering on site should be done from a safe distance and in full compliance with local laws and warning signs. Always stay alert and prioritize your safety while mapping near power infrastructure. Never enter fenced, restricted, or hazardous areas.

This documentation does not encourage or expect mappers to cross barriers or access private or protected property under any circumstances.

Covered features

This page focuses on how to map overhead power lines. These are visible wires, that we see every day in urban and rural areas, as well as in transmission corridors in nature. They are typically supported by poles or towers, and are easily identifiable as energy infrastructure.

In the following sections, we'll see how to identify power lines, tag their visible components, and map where they start and end.

This page does not however cover underground or underwater cables, which are tagged using power=cable. While both lines and cables carry electricity, they differ in construction, location, and mapping and tagging practices.

How to find lines

To locate power lines that may need mapping, you can try the following approaches when looking at satellite imageryor surveying safely on the ground :

  • Follow existing infrastructure. Many power lines are already partially mapped in OSM. By tracing them, you may spot missing segments, incomplete tagging, or unmapped branches.
  • Check near substations. Most of the time, overhead lines connect to substations. Check the surroundings of existing substations for lines that may be missing or inaccurately mapped.
  • Check near energy-related facilities. Power plants (nuclear, thermal, hydro, wind, solar) and large industrial sites are typically connected to the high-voltage transmission network. These areas are good places to find major power lines.
  • Check in populated areas. Low-voltage distribution lines are commonly found in residential neighborhoods, commercial zones, and urban streets.

Additional note : If you're short on inspiration and cannot find what needs to be mapped, you can refer to Osmose in the topic Power, or to OpenInfraMap.

How to map

Common principles

Beginning and end of lines

Every overhead power line should have clearly defined start and end points. These typically connect to one of the following structures:

A good mapping practice is to only map what is visibly verifiable. You should trace a power line based on:

  • The visible supports (towers or poles).
  • Or clearly identifiable shadows of the wires in aerial imagery.

If the line becomes unclear due to missing or low-quality imagery, do not continue drawing the line blindly. Instead, stop at the last confirmed visible support.

Physical components of a line

A power line is made up of several physical elements. The most common are:

  • Wires : Electricity conductors represented as a way and tagged with power=line or power=minor_line, according to the function and voltage of the line.
  • Supports : Structures represented as a Template:Icone. These are usually towers (power=tower) or poles (power=pole) that hold the wires/conductors above the ground.
  • Insulators: They prevent electrical contact between the wires and their supports.
    • They are not mapped when mounted on a standard power=tower, as this is considered implicit.
    • When placed on a power=portal at a substation entry, they can be mapped as node and tagged with power=insulator. This node serves as the connection between the power=line way and the power=portal way.
  • Terminals : Points where a line ends or transitions from overhead to underground. They are tagged as power=terminal and represented as a node.
Type of component Wires/conductors Supports Insulators on a power tower Insulators on a power portal Terminal
Illustration
Example in satellite imagery Not mapped in OSM.
Note The shadow of the power line's conductors are clearly visible in this satellite image. Two different types of power towers one next to another, supporting different voltage lines. Insulators on power towers are not drawn or tagged in OSM. Insulators on power portals are drawn and tagged when the portal is being used by a line. A power line ending on a power terminal on a building.

Types of lines

Transmission and distribution lines

Power lines serve different functions depending on heir voltage and position in the grid:

  • Transmission lines move high-voltage electricity over long distances, usually between power plants and substations. They are tagged with power=line and their support structures are usually different types of towers.
  • Distribution lines carry mid and low-voltage electricity from substations to end users (homes, businesses, smaller industrial facilities). They are tagged with power=minor_line and their support structures are mostly poles, and less often smaller power towers

Knowing and adding the voltage=* helps clarify the line’s role. For more information on power line classification, please refer to the dedicated wiki page.

Types of lines Transmission lines Distribution lines
Where to find them Near power plants, substations and big industrial facilities. In transmission corridors over big distances. Near distribution substations, in cities and rural areas. Near final energy users.
Illustration of lines
Types of support
Examples in satellite imagery
Recommended mapping and tags way power=line & voltage=*; node power=tower way power=minor_line & voltage=*; node power=pole

Lines, bays and busbars

Different types of power lines are mapped as way, but they serve different purposes:

  • As seen above, lines tagged with power=line or power=minor_line are overhead conductors used to carry electricity outside substations.
Illustration of busbars and bay lines in a substation in Ebingen, Germany
Illustration of busbars and bay lines in a substation in Ebingen, Germany
  • Bays, tagged with power=line + line=bay) are short internal segments within substations that connect incoming or outgoing lines to specific equipment (portals and transformers) within switchgear zones. They represent the entry/exit path of a line inside the substation.
  • Busbars, tagged with (power=line + line=busbar) are conductive bars that distribute electricity across multiple bays or components within a substation. They act as internal connection hubs.

Only bays and busbars are located inside substations. Properly mapping them as way and adding appropriate tags, including voltage=*, improves the detail and topology of substations.

For more guidelines on substations, please refer to the dedicated wiki page.

Supports

Supports are the physical structures that hold up power lines above the ground. They are mapped as node that is on the line way, and tagged based on their type:

  • power=tower for metal towers, mostly on high voltage lines.
  • power=pole for utility poles, mostly on mid- and low voltage lines.
  • power=portal for line entry/exit frames, usually near substations.
  • power=terminal for transition points from overhead lines to underground or buildings.

They are key elements of the network and should be precisely placed in OSM, as tools like Osmose use them as quality indicators.

Power towers

power=tower nodes represent tall, metallic lattice structures used to support high-voltage transmission lines. They are usually spaced far apart and appear on satellite imagery as star- or cross-shaped structures with visible shadows. Key characteristics:

  • Used for power=line (transmission) and sometimes power=minor_line when strong support is needed, for instance when the line makes a sharp angle.
  • Spaced regularly, but distance varies with terrain, voltage, and tower design. As an example, towers supporting a 220 kV transmission line on a flat ground can be spaced 250m-450m.
  • Easily visible on aerial imagery due to size and geometry.

Check more atttributs as well as different tower designs on the dedicated page.

Do not use voltage=* on tower or poles, as this is tagged on the line itself.

Power poles

power=pole represent smaller vertical structures, usually made of wood, concrete, or metal. They are used for medium- or low-voltage distribution lines and/or power=minor_line, and are more common in urban and rural residential areas.

Key characteristics:

  • Can appear as simple vertical lines in satellite imagery.
  • Much closer spacing than towers. Poles may be 20m-150m apart.
  • Occasionally used for high-voltage lines where towers are impractical.

They are mapped as node, tagged with power=pole, and can use the same attributes as towers.

Power portals and insulators

power=portal represents large structural frames used at the entry or exit points of substations. They support the conductors as they transition from overhead lines into substation equipment.

Key characteristics:

  • Usually visible on aerial imagery due to their square or П-shaped structure.
  • Mapped as a way connecting the two base node that are the portal's legs. If satellite imagery is not the best, the portal can be mapped as a single node.
  • Often support a power=insulator node in the middle of the structure, where the line connects. If satellite imagery is not the best and the portal is mapped as a single node, there is no need to add the insulator.

For more information on mapping power portals, please refer to Power networks/Guidelines/Substations

Power terminals

An indoor substation inside a building requires connections between outdoor power lines and indoor equipment.
This transition involves passing through building walls with specific insulation requirements. Mapping terminals improves network continuity by marking the limit between visible overhead infrastructure and unmapped or underground segments.

Key characteristics:

  • Found at the end of a line where it disappears underground or in a building.
  • Often located near substations, buildings, or at the edge of urban zones.
  • Use power=terminal on a node to map the points where power lines are anchored to the building.

Line management

Additional note on line management near a substation : Upon entering a substation, a power=line with circuits=1 and cables=3 should be connected to a single power=insulator node.

In case you have to end a multiple circuits power line (for instance 2 circuits with 6 cables or more), it should split in several separate 1-circuit lines. Mind adding line_management=split on the tower where the circuits split.

For more information on how a line should be mapped entering a substation, please refer to Power networks/Guidelines/Substations

Additional tagging

Here are some of the most commonly used tags that help add more detail to mapped power lines.

  • frequency=* : standardised on national or regional level to ensure compatibility across the power grid.
  • cables=* : especially usefull in the case of line management.
  • circuits=* : espectially usefull in the case of line management.
  • operator=* : helps identify ownership and responsibilities, and supports data analysis by distinguishing networks managed by different entities

Some of this information can be collected through field surveys or by consulting documents and data from national or local energy operators.

For a full list of available tags and attributes, see the dedicated page.

Quality assurance

Common mistakes

Supports not positioned on the line: Sometimes, power towers or poles are mapped as node placed next to the power line instead of directly on it. This should be avoided. All towers and poles should be positioned on the line way.

A notable exception is for disconnected towers near substations, which serve as backup structures in case of failure on the active line.

Reference works

Other mapping guidelines

See also