Insulation Piercing Connector, aslo could be named IPC, tap piercing connector, branch piercing connector etc. This is the accessories normally applicable for overhead lines. For insulated copper and aluminum wire. They are safe to use and are completely insulated, no need to strip wire. They can be installed on energized conductors with no contact at any point. No spacer required between connections. So it is easy to install. Shear-head bolts ensure proper torqueing every time.
And the piercing connector could be tested underwater 6KV 1 minute to check the water tightness performance.