Search

Premium Membership

Learn about power engineering and HV/MV/LV substations. Study specialized technical articles, electrical guides, and papers.

Home / Download Center / Electrical Engineering Books and Technical Guides / Electrical engineering guides / Learn earth ground resistance principles, testing methods and applications

Why test grounding systems?

Good grounding isn’t only for safety. It is also used to prevent damage to industrial plants and equipment. A good grounding system will improve the reliability of equipment and reduce the likelihood of damage due to lightning or fault currents.

Learn earth ground resistance principles, testing methods and applications
Learn earth ground resistance principles, testing methods and applications

Over time, corrosive soils with high moisture content, high salt content, and high temperatures can degrade ground rods and their connections. So although the ground system when initially installed, had low earth ground resistance values, the resistance of the grounding system can increase if the ground rods are eaten away.

Grounding testers are indispensable troubleshooting tools to help you maintain uptime. With frustrating, intermittent electrical problems, the problem could be related to poor grounding or poor power quality.

Components of a ground electrode
Components of a ground electrode

That is why it is highly recommended that all grounds and ground connections are checked at least annually as a part of your normal Predictive Maintenance plan.

During these periodic checks, if an increase in resistance of more than 20 % is measured, the technician should investigate the source of the problem, and make the correction to lower the resistance, by replacing or adding ground rods to the ground system.


What affects the grounding resistance?

First, the NEC code 250-83-3 requires a minimum ground electrode length of 2.5 meters (8.0 feet) to be in contact with soil.

But, there are four variables that affect the ground resistance of a ground system:

  1. Length/depth of the ground electrode
  2. Diameter of the ground electrode
  3. Number of ground electrodes
  4. Ground system design
Title:Earth ground resistance – Principles, testing methods and applications – Fluke
Format:PDF
Size:4.9 MB
Pages:16
Download:Right here | Video Courses | Membership | Download Updates
Learn earth ground resistance principles, testing methods and applications
Learn earth ground resistance principles, testing methods and applications

Premium Membership

Get access to premium HV/MV/LV technical articles, advanced electrical engineering guides, papers, and much more! It will help you to shape up your technical skills in your everyday life as an electrical engineer.
More Information

4 Comments


  1. Patrick Toussaint
    Jul 10, 2020

    Très bon article. Merci de partager avec nous toutes ces précieuses informations.


  2. Samuel Francisco Pongo Porras
    Jul 09, 2020

    Excelente, sus enseñanzas son practicas, gracias


  3. Samer Mahmoud almasri
    Jun 10, 2020

    Your articles is too much good


  4. Pravin Chavan
    May 07, 2020

    Your articles is too much good
    For understanding with pictures
    So thanks very much
    And continue gave electrical information to us
    Thanks very much

Leave a Comment

Tell us what you're thinking... we care about your opinion!

EEP Academy Video Courses

The learning platform for LV/MV/HV electrical engineers. Learn from experienced engineers and sharpen up your knowledge.
Schneider Electric - Coming back stronger together!