Sähkönjohdon

Sähkönjohdon (lit. “electric conductor”) refers to any material or device that conducts electric current. In practical use the term most commonly denotes insulated copper or aluminium wire that forms the core of electric circuits, powering appliances or transmitting power over distances. A conductor must have low electrical resistance, high mechanical strength, and adequate thermal and chemical stability to withstand operating conditions.

The typical construction of a modern sähkönjohdon consists of a metallic core surrounded by one or more layers of insulation such as polymer, polyethylene, or PVC. Cables may also include protective sheath, shielding, or a metallic laminate that provides additional mechanical support and electromagnetic compatibility. For long‑distance transmission the core is usually aluminium, selected for its favorable weight‑to‑strength ratio and cost; for building wiring copper is preferred because of its higher conductivity and better insulation properties.

Sähkönjohdon are classified by voltage rating (low voltage, medium voltage, high voltage), current carrying capacity, temperature tolerance and construction (e.g., insulated, armored, XLPE). Standards such as IEC 60228 and IEC 60364 specify performance, safety requirements and testing procedures. Safety design features include over‑current protection, insulation continuity, and insulation resistance monitoring. In many countries of the European Union, products must carry the CE mark indicating compliance with health, safety and environmental regulations.

The manufacture of sähkönjohdon involves extrusion, insulation sheathing, optional vacuum impregnation and quality control measures to verify mechanical and electrical properties. Environmental considerations include recycling of copper and aluminium, proper disposal of insulating polymers and the use of low‑VOC (volatile organic compound) coatings to reduce emissions during production and service.