Drilling, turning, countersinking, shaving, planing, lapping, broach, dressing, sawing, grinding, sharpening, etc. of metallic pieces
Repair and maintenance of house boilers
Building of lines and networks of telecommunication
Terracing work: digging, grading of construction sites, opening of trenches, removal of rocks, destruction with explosives, etc.
Ground-water lowering and dredging of construction sites
Removal on construction sites
Installation in buildings or in other projects of building of: heating systems by electricity, gas and fuel, boilers, materials and pipes for ventilation and air conditioning, etc.
Setting of electrical installations of heating
Electro-technical installation works at buildings
Electro-technical installation works, with the exception of those executed at buildings
Plumbing works
Other types of technical and scientific activities
Installation of heating, air-conditioning and ventilation