• Skip to main content
  • Skip to primary sidebar
  • Skip to footer

GreyMatters

Electrical Earthing System Design & Soil Resistivity Testing

  • Home
  • About
    • Contact Us
  • Blog
  • Earthing Services
    • Earthing Design Services
    • Lightning Protection Design
  • Earthing Training Courses
  • XGSLab
    • XGSLab Services
    • XGSLab Online Demo
    • XGSLab Sales
  • Members Academy
Home » Ask the Experts Electrical Earthing Blog » Soil Resistivity Testing Why Measure Soil Resistivity?

13/09/2013 By Ian

Soil Resistivity Testing Why Measure Soil Resistivity?

Soil Resistivity testing why measure? is Part 2 in a series of short posts on Soil Resistivity Testing and the common mistakes encountered, with practical advice on how to avoid Soil Resistivity Testing 10 Common Mistakes.

Soil Resistivity Testing 10 Common Mistakes

This is a series of short posts on Soil Resistivity Testing and the common mistakes encountered, with practical advice on how to avoid Soil Resistivity Testing 10 Common Mistakes.

Soil Resistivity Testing Why Measure Soil Resistivity?

The ‘Soil’ itself forms the very medium that any fault current will flow through.  Therefore, understanding the electrical properties of the soil in which an earthing/grounding system is deployed is absolutely vital.  Soil Resistivity constitutes the foundation for any electrical earthing design and cannot be understated.  It is a primary component to all Electrical Safety Calculations, such as, the permissible touch voltage calculations, the EPR (Earth Potential Rise), Hot Zone calculations, and individual system elements.

Soil Resistivity and the soil structure can have a massive effect on the complexity of the earth/ground grid design.  The soil acts as part of the return path for the fault current to source; higher soil resistivity will lead to a higher earth grid impedance value(s) leading to a higher Earth System grid voltage rise (Earth Rise Potential), which in turn gives rise to higher surface voltages across site.  Surface voltages, if not controlled with appropriately positioned grading conductor design, could lead to an unsafe condition.

Every Electrical Power System design relies on understanding all the component parts (impedance’s) and Electrical Earthing Design is no different.  The ground or soil is another component part in a circuit design… HOWEVER, whereas all the other constituent parts behaviour’s are well understood, e.g. the cables, transformers, generators, VT’s, CVT’s, etc. The soil on the other-hand, is a ‘natural’ semi-conductor, which will have a unique set of electrical properties and be subject to infinite variability from site to site.

soil-resistivity-layers

This set of unique properties are analysed and characterised into what is known as a ‘Soil Model’.  This soil resistivity model can be made up of many layers going down to depths of many 10’s of meters in order to understand how much of the energy from a fault (an unplanned release of energy) will a) pass through into the soil, and b) for each layer, how much will enter and travel through each respective layer.

data-centre-soil-model

Example Soil Model – CDEGS RESAP

The amount of energy passing through each layer has a particular relevance when considering ‘Surface Voltages’ and the step and touch potential (voltage) safety calculations.  For example, if the site has a LOW-ON-HIGH resistivity model, then more of the fault energy will prefer to travel in the upper layer, whereas, a HIGH-ON-LOW would encounter the reverse, where more of the Earth Return Current will prefer to travel in the lower layer.  Both the example scenarios are important to understand when designing earthing arrangements to provide safety from the system.

These points alone support the importance of Soil Resistivity Testing.  Click for more information on how to avoid the common mistakes, or simply get in touch – we’re here to help!

Filed Under: Soil Resistivity Tagged With: BS7430, Earth Rise Potential, EPR, fault current, Soil Resistivity Testing, Soil Resistivity Testing 10 Common Mistakes

Electrical Earthing Training – Free Trial

Do you want to understand more about Electrical Earthing System Design – Greymatters Academy is our Earthing Training site take a look or access your free trial here.

Recent Posts:

Why is a hot site a problem

Hugh takes us on a deeper dive into hot sites and answers the question ‘Why is a hot site a problem?’ You can find the webinar replay here. Hugh: Hello, everyone, thanks for joining our webinar this morning. This is a continuation from our previous session where Ian introduced the concept of a hot site […]

why am I getting a hot site?

Hello, and welcome this month’s topic, Ian answers the question Why am I getting a hot site? You can find the webinar replay here. Now for those that know me, I like to start these sessions with a thought of a concept that I’ve come across over the week. This is another one from James […]

Power Systems Design

Are you involved in Power Systems Design – You can now watch tens of hours of webinars in just a few minutes as I’ve summarized the top 3 ideas from over 17 technical webinars during the past 12-months.

Why is a hot site a problem

SPD (surge protection devices) are almost a prerequisite for every electrical and lightning protection system. Knowing when these devices are working or not can be a real pain. Usually, we’re forced to physically open up live panels to check if the plethora of SPDs is still functioning; very often, this task is made even more […]

why am I getting a hot site?

Testing an Earth/ground electrode is usually the final piece of the puzzle. Measuring the earth electrode’s resistance can verify and validate the design. The Earth measurement verifies that all the safety-critical calculations, assumptions and solutions made during the design phase match its predicted performance in the physical world. Earth testing can easily introduce errors that […]

About Ian

This post is written by Ian Griffiths, Principal Engineer at GreyMatters, an Earthing & Lightning Consultant of 28 years, one of the top 1% accredited CDEGS and XGSLab consultants and professional advisor to international utility companies, data centre and infrastructure developers.

Primary Sidebar

Take this short quiz

HV Earthing Quiz

Online Earthing Courses

Free Trial Learn More

Free Online Course – Learn Ohms Law in 10 minutes or less!

Learn Ohms Law

Our Top Earthing Post

Electrical Fault Theory

Blog Categories

  • Acadamy (2)
  • Anti-Theft (1)
  • CDEGS (5)
  • Earth Testing (6)
  • Earthing Designs (3)
  • Earthing System Design (16)
  • Earthing Systems (4)
  • Electrical Earthing (34)
  • General Post (9)
  • Lightning (7)
  • Lightning Protection Design (15)
  • Lightning Strike (1)
  • Renewable Energy (2)
  • Soil Resistivity (16)
  • Soil Resistivity Testing (10)
  • Solar (3)
  • XGSLab Updates (2)

Tag Cloud

BS7430 BS EN 50522 CDEGS data centres earth electrode Earthing Earthing Arrangements earthing design earthing standards Earthing system design earthing systems earth potential rise Electrical Earthing System Design Electromagnetic Field Theory electromagnetic interference EMI EN 50522 EPR Finite Element Analysis Finite Element Analysis Software greymatters Grounding HV Earthing HV Earthing Protection lightning lightning danger Lightning Protection lightning strikes Rise of Earth Potential risk management ROEP Soil Resistivity Soil Resistivity Methods Soil Resistivity Testing Soil Resistivity Testing 10 Common Mistakes Soil Resistivity Testing Methods soil structure Step Potential Step Voltage Surge Protection Tag Archive - Lightning Strike Touch Potential Touch Voltage what to do in a thunderstorm what to do when lightning strikes

Footer

  • Terms
  • Privacy
  • Cookies

Copyright GreyMatters © 2022