What's under the lid?

Perhaps you've caught a mouse crawling into its hiding place or a lizard disappearing through a crevice.. But, Have you ever observed a man who enters an open hole in the middle of the street?

Sometimes, on the floor of the streets there is an iron disc. It's the cover of a manhole. Beneath her opens a deep black hole. One day you see a man who places a small fence around the hole and descends through it.

The man lights a flashlight and a large number of pipes and cables appear around him. They are the water and gas pipes and the cables that supply electricity from the plant to all the houses in the sector. But, What is that man doing down there? You are repairing a damaged cable or tube or perhaps you are working on a new installation.