Cable tray fittings : Names and functions

Different types of earth rods

Types of earth rods 

Types of earth rods

 1) Solid copper earth rods

 2) Copper bonded steel earth rods 

 3) Galvanized Steel earth rods

 4) Stainless steel earth rods 

Solid copper earth rods

It is made from high conductivity hard drawn copper 

Advantages

It is used for soil with high moisure and salt content and is very corrosive 

 It is used where high fault currents are expected .

Disadvantages 

The solid copper is a ductile metal that will often bend when driven into soil so it is not suitable for use when a deep driving into the ground is needed 

Solid copper earth rods are high expensive compared to other types of earth rods

Copper bonded steel earth rods 

 it is made by electroplating 99.9% pure electrolytic copper (with thickness not less than 250 microbs) onto a low carbon high tensile steel bar .

The copper layer is moleculary bonded to the steel bar so it will not tear or slip when driven into the ground. 

Advantages

It is considered the most efficient and cost effective type of earth rods.

It has high mechanical tensile strength and resistance to corrosion at lower cost as compared to other types of earth rods (solid copper or stainless Steel)

The high mechanical tensile strength of the steel bar enables the rod to be driven to great depths

The rod is usually treated to avoid oxidation of the copper bonding.  

Galvanized Steel earth rods

In this type,the low carbon high tensile steel bar is hot dip galvanized with a coating of zink .

The zink coating will delay the corrosion of the steel bar by providing a sacrificial barrier.

Advantages 

It is the cheapest of all earth rod types.

It has good corrosion resistance and conductivity. 

The conductivity of zinc is 2.5 times the steel and more anti-corrosive and conductive

Disadvantages 

It has the lowest resistance to corrosion 

It has the lowest electrical conductivity and poor current carrying capacity. 

Applications

The galvanized steel earth rods are suitable for use in non critical earthing systems in temporary structures such as antennas and electrical panels in construction sites .

Stainless steel earth rods 

It is made of stainless steel bar

Advantages 

It is used when extremely corrosion resistance and high mechanical strength is needed .

The stainless Steel earth rod is treated with an oxide layer that makes it more resistant to corrosion than copper.

It is used to overcome many of the problems caused by the galvanic corrosion that can take place between buried dissimilar metals being in close proximity to each other .

Stainless Steel earth rod provides high mechanical strength so it is unlikely to break or bend when driven into the ground even in rocky soil.

Disadvantages 

It is the most expensive of all types of earth rods .

It has a lower electrical conductivity than other types of earth rods .

The current carrying capacity of steel earth rods is poor compared with copper earth rods

Application

It is primarily used in marine/shore environments and industrial processing .