What is it? Failures in grounding systems How is  a measurement study made?
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Measurements of
Grounding and Lightning Rod Systems


A measurement study of the grounding and lightning rod systems is a study of the resistance of the grounding system and/or lightning rod system of an installation, to verify that the values of resistance meet the standards.

According to the Mexican Official Norm issued by the Secretary of Work and Social Prevention, NOM-022-STPS-2008 , a  "Measurement Resistence Study of the Grounding and Lightning Rod Systems" must be conducted every year.

The purpose of this study, requested annually by the Secretary of  Work and Social Prevention, is to make sure that all static currents are being given  the appropiate dissipation, and to control:

  • the generation and accumulation of statical electrical charges, and to prevent possible effects of the atmospheric discharges that could damage the physical integrity of persons.

The grounding system must have the minimum resistance within an installation.

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Why do the grounding systems fail or why are there problems with the measurements? 

Some of the most common problems in the measurements and failures of grounding systems are:

1.- Uncalibrated measuring equipment.

2.- Failure to implement appropriate methods of measurement.

3.- Untrained staff.

4.- Taking measurements in the wrong places.

5.- Failure to comply with the standards, which indicates that a grounding system measurement must be performed every year.

6.- Lack of maintenance to the grounding system.

7.- Grounding system deterioration (corrosion).

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How is a grounding and lightning rod systems study made?

The measurement of the grounding and ligthning rod systems must be taken by qualified and certified staff, who develop:

- The study and measurement report (includes photos), with the results of the ohmic resistance values, as well as the continuity in the grounding points.

- In order to take the measurements of the soil resistivity and grounding and lightning rod systems resistance, is necessary to have the following materials:

  • Ground resistance tester with four terminals.
  • The tester is used to take the measurement of the resistance of the grounding system; this equipment can measure resistance from 0.01 to more than 4000 Ohms. The equipment must has a current calibration certificate.
  • Four metal pikes approximately 50 cm long.
  • Four insulated cables to connect the pikes to the tester.

Note: We sell ground resistance tester for the measurement of the grounding system resistance and we offer advise in how to use of it.

- Corrections to the grounding systems.

The method used to take the measurement of the soil resistivity is the Wenner Method . The Fall Potential Method (62%)  is used to measure the ground resistance of the grounding and lightning rod systems. 

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What should be included in a measurement report?

The documentation that comes along with the results of the measurement:

  • Copy of the calibration certificate of the equipment used.
  • Description of the equipment used.
  • Description of the use of equipment.
  • Record of the measured values of the ohmic resistance.
  • Conclusions and recommendations to follow.

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Some of the companies we have made this study for:





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Cerro de las Campanas No. 3,
Desp. 509, Col. San Andrés Atenco,
Tlalnepantla, Edo. de México, México, CP. 54040
Tel/Fax: 53 79 28 00 / 01

Hugo Hernández

General Manager


Michelle Hernández

Technical Manager


Ingrid Hernández

Commercial Manager





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