Copper is one of the shiniest metals that conduct electricity. Many items are made with copper, such as decorative lamps and the bottoms of high-end pots and pans, because it is a durable metal. Copper electrical wire has an outer coating to keep it from rusting, corroding and turning black. The conductivity of copper wire remains in clean wiring although the coating may burn onto the wire in the case of a fire or sparks. Cleaning copper wire correctly will restore the shine.
Wash the burnt copper wire thoroughly in dish soap and water to remove any traces of oil or grease or burnt wire coating. Pull small pieces of coating off the wire by hand.
Rinse the copper wire thoroughly so that no soap residue remains. Dry the copper wire with a towel and set it aside to let it dry completely.
Cut a lemon into six wedges with a sharp knife. Squeeze the lemon while holding it over the copper wire so that juice starts to drip on the wire. Rub the copper wire with the lemon while holding and squeezing the lemon.
Squeeze a second lemon wedge so that most of the juice drips out onto the wire. Sprinkle a heavy application of table salt on the lemon wedge and rub the wire with it.
Repeat rubbing the wire with salt and lemon as necessary until the copper is shiny and clean.
To clean long lengths of copper wire start at one end and clean one section at a time. When one area is clean and shiny move down and clean another section until the entire length is clean. Lemon concentrate may replace the fresh lemon though the fresh lemon juice will work more quickly to clean any type of copper. Lemon oxidises the copper to bring back its natural lustre and salt acts as a natural abrasive.
Lemon juice and salt will burn cuts on hands and fingers. Wear rubber gloves to protect from burning.