It's better known as cable 'greening'. ... Although fumes may be given off when PVC is decomposing (this statement is applied to house wiring) it would not be considered to be a health hazard, but there is a danger that the breakdown of a cable could cause an electrical fire.

Why do wires turn green?

Both colors are caused by oxidation as the copper reacts to elements in the environment. The green oxidation is commonly seen when pool chlorine is stored in the same room with electrical equipment and minimal ventilation, producing copper sulfide or hydrated copper sulfate.

What causes green corrosion on copper wire?

Copper turns green because of chemical reactions with the elements. ... Just as iron that is left unprotected in open air will corrode and form a flaky orange-red outer layer, copper that is exposed to the elements undergoes a series of chemical reactions that give the shiny metal a pale green outer layer called a patina.