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
- 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.
- 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.
- 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 electrode 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.
- 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 engineering 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.
- 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