The tag power=connection is used for a free-standing electrical connection between two or more overhead wires.
Connections usually occur on supports like power=tower, power=pole or even at line terminations/in substations.
However, we can sometimes find them where several overhead lines cross with no supports: the tag power=connection is required for such situations to clarify that the power lines are connected and electricity can flow between them.
How to map
On every free-standing power connection between two or more lines (mapped as power=line or power=minor_line), place a node shared by all connected ways and add power=connection, and additional optional tags as appropriate:
||It's a free-standing power connection linking two or more overhead lines.
||The power connection operator's name.
||amount of cables
||The amount of cables involved in the connection. On 3-phases systems it's possible to distinguish individual cables and use cables=1 on each connection.
|A connection between two 400 kV overhead lines without tower linkage