What is an earth termination? Why is it important? As you know, at Aiditec we work, among other things, on the installation of an external lightning protection system. But what is this, really? Well, as its name suggests, it is a system that is located on the external part of a community of owners, home, or industry of any kind. The purpose is to ensure an optimal level of protection, offering maximum safety to people, animals, and electrical installations when lightning forms during a storm. In other words, it is what is commonly known as a lightning rod.

In this regard, at Aiditec we work with Early Streamer Emission (ESE) lightning rods which will be located at the highest points of the structure. Here, the location of the earth terminations is taken into consideration, ensuring that the path of the down-conductors is as short and straight as possible. In addition, we try to avoid the proximity of electrical, telephone, data conduits, etc., and their crossing with them.

On the other hand, but no less important, the tip of the lightning rod must be located at least 2 meters above any element within the area it protects, including antennas, cooling towers, roofs, tanks, etc. But one of the keys to these systems was mentioned in the lines above, and that is the earth termination.

And, the reason for the importance of this section is the peculiarities it has and that affect the installation of this lightning protection system. The peculiarities of earth terminations are as follows:

  • Unless absolutely impossible, earth terminations must be oriented towards the exterior of the building.
  • One earth termination will be made for each down-conductor.
  • It is recommended to join vertical ground rods with a minimum total length of 6 meters, arranged in a triangle and spaced by a distance at least equal to their buried length, and joined together with a conductor buried in a trench at least 50 cm deep.
  • The resistance value of the earth terminations must be as low as possible and always less than 10 Ω. When it is not possible to achieve these values, 160 meters of buried electrode must be installed for protection level I or 100 meters for the other protection levels, provided that the length of each vertical or horizontal element does not exceed 20 meters.
  • Each earth termination will have an inspection pit and a disconnecting link.
  • Measurements will always be carried out in isolation from any other conductive element.


But, the most important thing in this whole process is that the installation of a lightning protection system must always be carried out by specialized technical personnel and in compliance with all the requirements established in the current regulations.