The most commonly installed variety of earth rod is copperbonded steel-cored. The copper coating is around the sides of the rod is thin, usually about 250 microns. Copper is a reliable variety of conductor, and is not as prone to deterioration as steel. Far stronger than copper, steel provides a solid core that can be driven into the ground, whereas a solid copper rod would not only be significantly more expensive, but would most likely buckle if driven into the ground. Combined they benefit from the best attributes of each metal, but also sadly, the worst attributes.
If the copper coating is damaged it will leave the steel exposed. Furthermore the steel tip and end of the rod will remain exposed. Steel will deteriorate in line with the local acidity, alkalinity, salinity and toxicity levels.
The image to the right demonstrates the remains of a 1.2m copperbonded steel earth rod 3 months after installation. As you can see all that is left is the threaded end, with the whole piece about 50mm long. The quality of the rod is beyond dispute, it was produced by one of the leading global manufacturers with UL accreditation. In this instance the local ground mass had higher salinity levels due to its coastal location. The problem is not the quality of the product, it’s simply the inherent weakness of the product-type.
In the event of a fault current event the earth rod would have provided no protection. Take a look again at the photograph and consider that an earthing system is much like a second parachute: when you need it to work it has to work or people can die. As earthing systems are infrequently checked, if at all, they need to be able to withstand any kind of environment, and on as permanent a basis as can be achieved. Earthing Services products and methods are permanent, and protect against deterioration.