Bourth (X) Mar 10, 2011:

Alternatively the air shaft might convey warm, foul air from the building, and the wiring might be to sensors detecting the temperature of that air, the "return air sensors", like the water-return sensor that is part of the control of my heat pump.

Bourth (X) Mar 10, 2011:

As always everything will depend on your context. It might be an air shaft in a building, used for ventilation, conveying cool (relatively) air, and from which your refrigeration system might draw the air it requires.

Priyank Aggarwal (asker) Mar 10, 2011:

The wiring is for a refrigeration unit.

David Goward Mar 10, 2011:

Common spelling mistake Should be "puits" (even in the singular).

What's the wiring for?