Premium Membership

Save 15% on Pro Premium Plan with discount code: UX778 (expires on October 31st). Study specialized LV/MV/HV technical articles and papers.

The ground grid

The substation grounding system is an essential part of the every electrical system. The proper grounding of a substation is essential and very important for the following two reasons. First, it provides a means of dissipating electric current into the earth without exceeding the operating limits of the equipment.

Best practice in substation grounding systems
Best practice in substation grounding systems

Second, it provides a safe environment to protect personnel in the vicinity of grounded facilities from the dangers of electric shock under fault conditions.

The grounding system includes all of the interconnected grounding facilities in the substation area, including the ground grid, overhead ground wires, neutral conductors, underground cables, foundations, deep well, etc.

The ground grid consists of horizontal interconnected bare conductors (mat) and ground rods. The design of the ground grid to control voltage levels to safe values should consider the total grounding system to provide a safe system at an economical cost.

The following information is mainly concerned with personnel safety. The information regarding the grounding system resistance, grid current, and ground potential rise can also be used to determine if the operating limits of the equipment will be exceeded.

Safe grounding requires the interaction of two grounding systems:

  1. The intentional ground: consisting of grounding systems buried at some depth below the earth’s surface
  2. The accidental ground: temporarily established by a person exposed to a potential gradient in the vicinity of a grounded facility

It is often assumed that any grounded object can be safely touched. A low substation ground resistance is not, in itself, a guarantee of safety. There is no simple relation between the resistance of the grounding system as a whole and the maximum shock current to which a person might be exposed.

(a) Exposure to touch voltage; (b) Exposure to step voltage
(a) Exposure to touch voltage; (b) Exposure to step voltage

A substation with relatively low ground resistance might be dangerous, while another substation with very high ground resistance might be safe or could be made safe by careful design.

There are many parameters that have an effect on the voltages in and around the substation area. Since voltages are site-dependent, it is impossible to design one grounding system that is acceptable for all locations.

The grid current, fault duration, soil resistivity, surface material, and the size and shape of the grid all have a substantial effect on the voltages in and around the substation area.

If the geometry, location of ground electrodes, local soil characteristics, and other factors contribute to an excessive potential gradient at the earth surface, the grounding system may be inadequate from a safety aspect despite its capacity to carry the fault current in magnitudes and durations permitted by protective relays.

During typical ground fault conditions, unless proper precautions are taken in design, the maximum potential gradients along the earth surface may be of sufficient magnitude to endanger a person in the area.

Moreover, hazardous voltages may develop between grounded structures or equipment frames and the nearby earth.

Title:Best practice in power substation grounding – Richard P. Keil; Commonwealth Associates, Inc.
Size:1.00 KB
Download:Right here | Video Courses | Membership | Download Updates
Best practice in power substation grounding
Best practice in power substation grounding

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


  1. Halid Mwasumile
    Jul 21, 2020

    We’re getting the best concepts of electrical engineering on development of technology for ELV,LV,MV,HV,EHV and UHV power systems. I’m sending my special congratulation to the entire team who is organizing EEP informations.

    From Professional Electrical Engineer Halid Mwasumile of United Republic of Tanzania.

    • Edvard
      Jul 21, 2020

      Thank you very much Halid, that’s very kind of you.

  2. Jitendra singh patel
    Mar 24, 2020

    I’m working in Jordan .I’m indian

  3. Olabode Aloba .M
    Mar 24, 2020

    Very educating and updating

  4. Khaled Mohseen
    Apr 13, 2019

    Dear sirs
    What are the membership fees?

Leave a Comment

Tell us what you're thinking... we care about your opinion! Please keep in mind that comments are moderated and rel="nofollow" is in use. So, please do not use a spammy keyword or a domain as your name, or it will be deleted. Let's have a professional and meaningful conversation instead. Thanks for dropping by!

  +  fifty nine  =  63

Learn to Design Power Systems

Learn to design LV/MV/HV power systems through professional video courses. Lifetime access. Apply a 15% discount code EAB77 and enjoy learning!

Subscribe to Newsletter

Subscribe to our Weekly Digest newsletter and receive free updates on new technical articles, video courses and electrical guides.