Our trained and qualified crews use the proper equipment and procedures for inspecting and accurately testing site electrical grounding and lightning protection systems. Using our test results, you can ensure compliance with regulatory standards and best practices.
Our engineers provide you with a complete electrical grounding audit and grounding safety survey. You can use this information to determine the integrity of your system and schedule corrective measures before an event becomes a tragedy. This means you reduce the probability of injury, lost time, and lost revenue caused by equipment and infrastructure damage as a result of lightning strikes and other high-energy transient events.
Your customized electrical grounding evaluation and electrical grounding site audit will provide a detailed analysis, based on comprehensive electrical grounding system analysis and testing. In addition to showing how your system measures up, the audit reports will disclose any deficiencies in your site grounding and provide recommended solutions for correcting them. You can pass the completed electrical grounding report to the appropriate designer, architect, or engineer to prepare drawings that meet your construction requirements.
Your audit will include:
- Site Survey: Electrical Grounding System Analysis.
- Specification Review.
- Electrical Grounding System Resistance Testing: Clamp-on Induced Frequency Test.
- Written Report with Recommendations.
- Certificate of Certification.
Some testing information
ComSite Construction Company follows the ANSI / ESD S20.20 Electrostatic Discharge Control Program Standard. Approved as an ANSI standard, ANSI / ESD S20.20: Development of an Electrostatic Discharge Control Program covers the requirements necessary to design, establish, implement, and maintain an ESD control program to protect electrical or electronic parts, assemblies, and equipment susceptible to ESD damage from Human Body Model (HBM) discharges greater than or equal to 100 volts. To schedule your free initial consultation, please do not hesitate to contact us or call 864-480-7680.
Ground System Resistance Testing: Site Compliance Testing. Many equipment manufacturers now require that the grounding system for their equipment must be 5-ohms or less and that resistance-to-ground tests be conducted on the grounding system to validate the warrantees on the equipment. The 3-point fall-of-potential method and/or the clamp-on induced frequency test are used to measure the resistance-to-ground of existing grounding systems.
Resistance-to-ground testing requires highly trained personnel to properly conduct the tests and ensure accurate results. In the past, many of these tests have been found to be invalid due to poorly trained technicians running the tests. Don’t let the warrantees on your equipment become “null and void” due to errors on the part of the people conducting those tests.
Our ground system resistance testing (which includes site verification and a certificate of certification) consists of:
- Clamp-on induced frequency tes.
- 3-point fall-of-potential test.
- Computer modeling for online sites.
- Site review of ground system.
- Soil resistivity test: Wenner 4 point soil resistivity testing.
- Computer analysis of the actual site grounding system and written report .
- Soil testing and computer modeling to determine the various soil resistivity layers.
To electrical people, ground testing is a matter of soil resistivity. We do that kind of testing, but also test the ground for structural properties. By utilizing the Wenner 4 Point system, along with soil resistivity results from geotechnical surveys, we’re able to map the dynamic time domain simulation of bus structures under various excitations. These include:
- Magnetic forces.
- Wind loading.
- Ice loading.
- User-defined forces and moments.
The ground system simulations results include:
- Magnetic force magnitude.
- Buss work displacements.
- Torques and moments.
- Tensile, compression, and shear forces.
- Tensile, compression, and shear stresses.
We provide reports of these quantities in time plot format and in tables of maximum values.We use meter elements to select the locations for the reports of displacements, forces, and stresses.
What reports are customers typically interested in? In our many years of experience, we have found those to be the following:
- Soil resistivity analysis
- Low frequency grounding / earthing analysis
- Frequency domain grounding / earthing analysis
- Line and cable constants (parameters) and induction analysis
- Detailed fault current distribution and EMI analysis
- Electromagnetic fields analysis
- Automated fast fourier transform analysis
- Simplified fault current distribution analysis
- Ground system resistance report
- Ground conductor current report
- Soil current density report
- Enhanced touch voltage computations
- Ground conductor voltage plots
- Fault current contribution reports
Qualified tower installers know to where to bond and where to ground. What’s the difference between these two concepts?
When you ground, you connect something to the earth (you can read more about this distinction in the IEEE-142, the Green Book and in the National Electrical Code, Article 250 and in other sources). So when you think of grounding, you could think of it as “earthing” to keep things straight in your mind. We ground for lightning protection purposes. We do not ground to create an equipotential plane, because the resistance of the earth is far too high to facilitate that. Anyone who’s done ground resistance testing can tell you this
When you bond, you create a conductive path between metallic objects. We bond for several purposes. For example, we bond metallic objects to prevent a flashover between them. For electrical systems, we bond to create a low-impedance path for fault current to flow.
Let’s address some common misconceptions about grounding:
- Myth: When you ground something, a person touching it is at the same potential as the ground rod and so can’t be electrocuted. The problem here is Ohm’s Law. You can stand on a ground rod and be electrocuted if your other foot is on the dirt because the earth has resistance and so does your body. Draw out the circuit on paper, and do the math.
- Myth: Grounding eliminates differences of potential. No, this is what bonding does. When you bond, you create an extremely low impedance path between metallic objects. That’s why lightning protection standards require bonding metallic objects on a roof to prevent flashover.
- Myth: Grounding eliminates electrical noise. This misconception arises from the misuse of the word “grounding.” We talk about signal ground, but it’s not actually ground (earth). Airplanes are not connected to the earth, yet their electronics have signal “ground.” What’s meant here is a reference plane, not an actual ground.
- Myth: Grounding creates a return path for electricity. This is a very dangerous myth to believe in. Suppose, for example, we eliminated the neutral wiring in homes and just used ground as a return path. This would make taking a shower a rather lethal experience. Similarly, consider the common 277V lighting system in commercial and industrial buildings. The return path is the neutral, not the bonding or grounding system. In cases where the installers have used the metallic raceway instead of a neutral (a code violation), the result has been undesired circulating current. Why? That brings us to our final myth….
- Myth: Electricity seeks the path of least resistance. This directly contradicts Kirchoff’s Law of Parallel Circuits, upon which our entire electrical infrastructure and all of our electronic devices are based. The reality is that electricity flows along all available paths, in reverse proportion to the resistances.
So, does grounding actually serve any purpose? Yes. The National Electrical Code devotes considerable space to this topic, as do the lightning protection standards. Grounding provides a path to earth for lightning and other high voltage transients. For towers, this is critically important. Lighting strikes tall structures, preferentially. So a tower, being tall, is essentially a big lightning rod. Without a lightning protection systems (which relies on grounding), the tower can suffer catastrophic damage from the million plus volts it gets hit with. But deficiencies in how that system is designed and/or installed can result in currents flowing through structural connectors, overheating those connectors, and weakening them over time. The lightning protection system diverts this energy to ground, thereby protecting the tower.
The three grounding standards in the USA are:
- IEEE-142, The Green Book.
- NFPA 70 (NEC), Article 250.
- IAEI Soares Book on Grounding.
The two lightning protection standards in the USA are:
- LPI-175, the Lightning Protection Institute’s Standard of Practice for the Design, Installation, and Inspection of Lightning Protection Systems.
- NFPA 780, the National Fire Protection Association’s Standard for the Installatoin of Lightning Protection Systems Article 250.