The Pole tool on the toolbar is use to place new poles on the ground, and to insert poles into an existing conductor:

It allows a specific type of pole to be placed at each location, so that when the conductor tool is used the pole type doesn't need to be changed each time - it will automatically match the type of pole denoted by the placed pole.

Left-click on the ground to place a new pole. Left-click on an existing conductor to insert a new pole into the conductor span at the clicked location.

For more information about adding, moving, modifying, and stringing conductors on poles, see Model your existing network
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