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Public-images-osm logo.svg wires
Number of wires per power cable. "single" (1), "double" (2), "triple" (3) or "quad" (4). Edit or translate this description.
Group: Power
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations
Useful combination
Status: in use

To describe the number of wires (better: sub-conductors) per power cable (better: conductor bundle) of an overhead power line section.


High voltage transmission lines often use conductor bundles (cables) each consisting of two or more individual sub-conductors (wires) separated by spacers. This has two main purposes:

  • Reduction of corona discharges. The strong electric field around a conductor can cause ionisation of the surrounding air. This may result in significant power losses and audible noise and it is therefore important to limit such coronal discharges. The electric field can be reduced by increasing the effective diameter of the conductor. A conductor bundle will behave similarly to a single conductor having a diameter roughly corresponding to the diameter of the bundle.
  • Mitigation of skin effect. AC current tend to flow at the surface of conductors. At 50 Hz the current cannot penetrate more than approximately 1 cm into the conductor. It is therefore inefficient to increase the diameter of thick conductors to reduce the electric resistance. A better way to increase the current capacity is to use bundled conductors. A conductor bundle having multiple thin sub-conductors will have a lower resistance than a single solid conductor having an equivalent cross section.

Conductor bundles are normally used at voltages above 200 kilovolt to limit corona losses but may also be used at lower voltages to increase the current capacity of the line.

Please note this is a physical property, qualifying a particular section of a given power line. Power lines may be composed of different sections with a different amount of wires per bundle (sections hasn't been built at the same time, for the same purpose or whatever). It's not recommended to use this key on relation route=power objects since a given route can go through several sections with different bundle configurations. Example on this route using triple wires section and two wires section.


Possible values are:

  • One wire (no bundle): wires=single
  • Two wires: wires=double
  • Three wires: wires=triple
  • Four wires: wires=quad

Other values are created by appending the phrase 'fold' after the numeral:

  • Five wires: wires=fivefold
  • Eight wires: wires=eightfold


The photo on the right shows an example of wires=double. You see three cables each with two wires.

Count Picture tag
1 JP Power Wires Single.JPG wires=single
2 JP Power Wires Double.JPG wires=double
3 JP Power Wires Triple.JPG wires=triple
4 JP Power Wires Quad.JPG wires=quad
5 JP Power Wires Fivefold.JPG wires=fivefold
6 JP Power Wires Hex.JPG wires=sixfold
8 JP Power Wires Octal.JPG wires=eightfold

Other keys

The number of cables of a line is tagged by cables=* (here ground/earth wires do not count). To distinguish wires and cables use this simple rules:

  • Wires are not insulated from one another, but insulated to the tower.
  • Cables are insulated from one another and to the tower.
  • Ground/earth wires are not insulated to the tower.

A note on terminology

The names of the keys wires=* and cables=* may have been chosen a little bit unfortunate. The more common term for "wire" is sub-conductor (IEV ref 466-10-21) of a conductor bundle (IEV ref 466-10-20). A single conductor (IEV ref 466-10-19) corresponds to wires=single. Similarly twin bundle, triple bundle and quad bundle correspond to wires=double, wires=triple and wires=quad, respectively. See also Wikipedia on conductors.