Tag Archives: ground rods

Components to an effective grounding system

An effective grounding system is one of the most important aspects of ensuring lightning protection. The purpose of this system is to provide a pathway for the lightning energy to safely flow to earth, as if this is not effective the extreme current -given the conditions- can find alternate pathways. If the current does deviate, the damage can range from electromagnetic interference on sensitive equipment and overloading circuits to electrical fires, arc flash and electrocution. For this reason, it is crucial to consult professionals when implementing one of these systems.

Grounding System Components

Effective_grounding_system_components

  1. Earthing network conductor. Conductor must have the current carrying capacity for the maximum fault current for the total clearing time of the fault. Copper or copper-bonded steel conductors are characteristically used for this purpose. WAPP offers various types of conductors for earth grids and bonding ranging from flat copper tape, various copper earth cables to proprietary ERICO Smoothweave cables.
  2. Interconnecting Joints. Connections between grounding conductors are essential to the functionality and reliability of the system, this is how the elements of the grounding system tie together. Exothermically welding the connections, by use of CADWELD provides a superior bond on a molecular level ensuring that it will never corrode or loosen which would otherwise damage the integrity of the electrical continuity. A more economical and procedurally simple alternative are mechanical connectors, these are of bolted, wedge and crimp type which, rely on the physical surface contact to maintain electrical connection. For above ground connections (e.g. fence clamps), this is an acceptable way of bonding.
  3. Grounding Electrode. The grounding electrode (or sometimes referred to as rod/stake) provides electrical connection to the ground and acts to dissipate current to it. Electrodes can be categorised as either “natural” or “made”. A natural ERICO_Ground_rods.jpgelectrode is intrinsic to the structure this could be metal underground water piping, effectively grounded metal framework of the facility, and/or the steel in reinforced concrete foundations. An electrode is considered made when it is implemented for the express function of improving the performance a grounding system this includes buried metal plates, buried mesh conductor and rods or pipes driven into the ground. The ground rod is the single most used, efficient and effective grounding device in the practice today. ERICO has developed bonded ground rods impervious to many issues common in cheaper ground rods, further information see copper ground rods.
  4. Soil Composition. The soil resistivity rating, a measure of ohm-meters, has a large impact on the performance of a grounding system and is to be known prior to GEM25Aengineering a proper grounding system. Based off the soil resistivity the design engineer will locate the area of the most conductive soil and from this, determine the depth the electrodes required to be placed accordingly. The best solution to improving earth composition can be altered to decrease its resistivity through the use of the cost effective Ground Enhancing Material (GEM). The optimal solution is the effective implementation of GEM to reach the desired resistance. There are other solutions such as bentonite which perform the same task however, are deemed inferior, for more information on this see GEM vs Bentonite.
  5. Electrode to Earth Resistivity. Rod surface area and earth composition are the main contributing factors. Doubling radius of the driven rod will reduce resistance by merely 10% and is not a cost-effective option. Doubling the rod length however, will theoretically reduce resistance by 40%. Placement of numerous rods that are driven to a predetermined depth in low resistivity soil.

Western Australian Power Protection (WAPP) offers obligation free consultation and quotation for grounding systems. To speak to a professional to address your specific needs find our contact information on our ‘Contact Us’ page


Copper Ground Rods

When it comes to choosing ground rods for an effective grounding system, you should know your facts and their application.

For a grounding system to operate effectively it is dependent on the ground rods. It is important that when you choose which ground rod to use, you consider many factors including their quality, resistance to corrosion, serviceable life and material costs. So, the decision should be based on these factors to make sure that the lightning protection systems and surge protection devices that rely on these aspects perform efficiently.

The condition of the ground where the ground rods are going to be driven into should also be taken into consideration in order to maximise the life and value of the grounding system.

Ground rods

There are different types of ground rods in use including copper-bonded, galvanized steel and stainless steel rods depending on the specific requirements.

The most commonly used ground rods are copper-bonded and galvanized steel rods. They both have a carbon steel core. The difference between these two rods is mainly due to their costs, service life (resistance to corrosion) and the materials used for / thickness of coating. ERICO’s copper-bonded rods are electrolytic coated with copper over a layer of nickel. Therefore they are known for better conductivity and high resistance to corrosion. Galvanized steel rods are coated with zinc which is prone to corrosion.

According to a study conducted by the National Electrical Grounding Research Project (NEGRP), the results showed that galvanized rods which were excavated after 8 to 12 years were a lot more corroded than copper-bonded rods. (As shown in the following photos).

Use of stainless steel rods are generally limited since they are very expensive compared to the rest by a large amount.  galvanized-ground-rods ground-rods

ground-rods_2Costs vs Benefits

Stainless steel is the most expensive one of all rods while copper-bonded are the least expensive. Stainless steel rods have the highest service life expectancy by a margin of 5 years compared to the copper-bonded rods whereas the margin of cost is much larger.

Copper-bonded rods have a longer serviceable life and a lower annual cost than galvanized rods.  Galvanized rods have a lower purchase price. But they can be more expensive than copper-bonded rods in the long term and their service life expectancy is also the shortest of all in comparison.  So, copper-bonded rods provide better value with longer service life.

Galvanized rods can be more beneficial in short term structures’ grounding systems that are stable.

But in certain cases, the ground rods to be used depend on their application and where they are going to be installed. This is because certain types of soils (highly corrosive soil) and land fill areas may not be well-suited with copper. Or in some cases where structures might be near an array of ground electrodes, stainless steel might be the best option. In these cases, we may have to go for the stainless steel rods but due to their high costs generally they are not widely used.

A technical report prepared by Chris Rempe (ERICO’s Grounding Products Manager) recommends that “galvanized ground rods are better suited for short-term, non-critical installations. For the majority of installations, copper-bonded and stainless steel rods provide better protection for people and equipment due to their longer service life.” (Rempe 2003).

Another report by Chris Rempe comparing copper and galvanized ground rods also suggests the same.

So, overall copper-bonded rods are more cost effective than galvanized rods and stainless steel rods also considering their longer serviceable life expectancy. (As shown in the graphs below).

ground-rod-annual-cost ground-rod-life-expectancy

Types of Ground Rods Costs Comparison Serviceable Life Expectancy Advantages Disadvantages Applications
ERICO’s Copper-bonded Higher purchase price than galvanized steel rods but less expensive than galvanized steel rods in the long term Lower service life expectancy in comparison to the stainless steel rods but only by 5 years Resistance to corrosion,Withstands repeated faults and surge currentLong service life Suitable for most driving / deep driving applications
Galvanized Steel Low purchase price, but more expensive than copper-bonded rods in the long term Lowest service life expectancy Lower initial cost /purchase price Vulnerable to corrosionShort service life Suitable for or non-critical, temporary,  short-term structures which may require shorter service life
Stainless Steel Most expensive of all Highest service life expectancy Longest service life High cost Better alternative for certain soils and land fill areas which are not compatible with copper

 

ERICO’s copper-bonded rods vs Inferior copper-cladded rods

ERICO’s copper-bonded ground rods have an electrolytic coating of copper over them. So, the molecular bond between the steel core and the copper coating is much stronger. Inferior rods are copper cladded which means they are just simply covered with a thin sheet of copper coating.

Under a certain pressure load, ERICO’s copper bonded rods will start to bend but they will not crack and the copper coating will not tear or slip when driven. Copper-cladded inferior rods can easily crack and crease to the outer cover while bending subjected to the same pressure load. This will damage the copper cladding when driven into the soil meaning it can put the whole grounding system at risk and considerably further decrease its serviceable life expectancy.

A document prepared by ERICO about maximising grounding system is available for you to read through this link: https://www.erico.com/catalog/literature/E1011B-WWEN.pdf

If you have any more queries on ground rods or need assistance in choosing the right ground rods for your use, please contact us on (08)9451 2199.

If you need more information on the different ground rods available, please go to the Ground Rods (or Earth Rods) page on our website.