Earthing is a fundamental step in any electrical system installation. Its proper installation also depends on the proper functioning and safety of equipment and people, as it protects against potential differences that can be dangerous in both cases. Why it is so vital, how to set up a project correctly and what regulations must be followed to install the earthing system of a lightning conductor are some of the main questions answered by Aplicaciones Tecnológicas.
Proper grounding provides a low-impedance path for electrical currents that protects installations, preventing these currents from finding unwanted paths that could cause damage to both people and electronic equipment connected to that network. Grounding also reduces electromagnetic noise, which improves signal quality and measurement accuracy of sensors.
The earthing system must also establish a reference potential by equipotentialising the system, which prevents variable voltages that can generate permanent overvoltages leading to equipment damage and even electrical fires.
In lightning protection systems (LPS), it is the earthing system that disperses the current, making its correct installation a vital step in achieving a safe system for structures and people.
From its most basic fundamentals to how how to to make a project from scratch, these are the five most frequently asked questions answered by Aplicaciones Tecnológicas’ specialists about earthing.
- Why is a safe earthing system important?
An earthing system is a direct electrical connection, without any cutting or protection elements, of the metallic parts of an installation with the earth through one or more buried electrodes, with the purpose of:
- Ensure that there are no dangerous potential differences between the installations and the immediate vicinity of the buildings containing them.
- To allow the passage to earth of fault currents or atmospheric discharges.
An earthing system must be designed and executed in an appropriate manner, as it is very difficult to maintain over time if it is buried.
In addition, the most durable joints will be made by APLIWELD Secure+ exothermic welding.
- Which elements do I need to make an earthing system?
The elements that are used in an earthing system, will vary slightly depending of the resistivity of the land.
- Electrodes for earthing
General earthing is usually done via a bare earth ring or horizontal conductor mesh buried in the ground, complemented by vertical electrodes to decrease resistance.
Earth pits are usually situated towards the outside of buildings. Their function is to provide an accessible manhole for any tests and inspections.
The connection to the earth pit is made at the bottom of the excavation, through a device that allows the disconnection of the earth conductors and which must carry an earth symbol.
- Earth bonds: permanent and mechanical
Connection components must ensure the continuity between the down conductor and the earthing. It is recommended that connections be made using the aluminothermic welding APLIWELD®, because unlike mechanical connections, welded joints do not degrade and are a permanent solution that is not going to deteriorated with the passage of time.
- Conductivity enhancers
Conductivity enhancers are used in high resistivity terrains, where obtaining a low resistivity ground value could be impossible, even with the installation of multiple electrodes. Conductivity enhancers achieve a moisture retention in the soil and provide ions that significantly reduce the resistance in a long lasting manner and without any corrosion.
- What is necessary to be able to make an earthing project?
In order to make a basic general earthing project, the following data are required:
For the estimate of the material required:
- Dimensions of the site on which the grounding can be carried out.
- Geo-electrical study with the resistivity of the ground/terrain by strata/layers.
- Target earthing resistance.
For the measurement of step and touch voltages:
- Maximum short-circuit current.
- Maximum duration of the short-circuit current or how long it takes for the protections to operate.
- Type of ground surface layer and thickness.
- What is special about lightning protection earthing systems?
Lightning current, being an impulse current, is discharged to earth in a different way than a current at industrial frequency. These are the special features according to the lightning protection regulations:
- An earth connection shall be made for each down conductor with at least two electrodes for each earth connection.
- The earthing resistance of the lightning conductor must be less than 10 ohms, measured independently of any element of a conductive nature.
- Avoid long earthing points (>20m) in order to ensure the lowest possible impedance.
- They should always be oriented towards the outside of the building.
- Should the general earth connection be connected to the lightning rod earth connection?
Yes. In all lightning protection regulations it is recommended to connect the general earth connection to the lightning conductor earth connection. This avoids potential differences, as well as serious problems of resistive coupling and shunts between earths.
However, in some cases this connection cannot be made directly, because it could lead to corrosion or electromagnetic compatibility problems (noise). In these cases, it is best to connect the earths with a spark gap type protector such as the AT-050K: ATVIA TT.
Under regular conditions, this protector keeps the earthing system isolated from each other, preventing corrosion and noise problems. When a discharge occurs and the potential rises in one of the systems, the spark gap will act by directly bonding both systems and thus preventing the current from passing from one to the other through the internal equipment and installations.
Creating a suitable earthing system
The choice of materials to achieve a good earthing system is crucial for a successful installation. Aplicaciones Tecnológicas has a complete range of products that facilitate the creation of an effective earthing system by reducing the resistance of the ground, the use of conductors with good resistance to corrosion and sections suitable for carrying current.
In addition, aluminothermic welding, also known as exothermic welding, is highly recommended for making connections between conductors, especially for earthig systems, because the molecular bonds guarantee the maximum efficiency and durability. APLIWELD® Secure+ is the most efficient and safest aluminothermic welding on the market, introducing an innovative tablet format, electronic initiators and remote ignition for further safety.
Aplicaciones Tecnológicas also offers a professional service of geoelectric surveys aimed at engineering and architectural firms, using advanced measurement technology with GEOELECTRIC EARTHING METER. The on-site measurements are carried out through a network of local partners. The measurements are processed and treated using Artificial Intelligence. Subsequently, our experts generate the professional report within 24 hours.
If you want to know more about how to make an earthing system, you can contact us by clicking this link.
You can also attend any of our earthing webinars by clicking on the link below.