Worker calmly fixing burst pipe - GIF

[jdurand]

One's inclined to wonder about those electricity cables in the full flow of the water.

since that's clean water and those are low voltage it shouldn't be too much of a problem.

Funny way to tap, I've normally seen it done through a ball valve. You put the clamp in place then put a hole saw through the open ball valve. When the hole is through you extract the hole saw and leave enough in the pipe (if you can) to hole back the flow while you close the valve. Can be done with very little liquid lost.