Grounding outside

Inside building there are situations where you can see 60-115 V AC between different equipment grounding points. When going outside the building the voltage differences can between different grounding points can become larger. In electrical engineering, Earth Potential Rise (EPR) also called Ground Potential Rise (GPR) occurs when a large current flows to earth through an earth grid impedance. The potential relative to a distant point on the Earth is highest at the point where current enters the ground, and declines with distance from the source. Ground potential rise is a concern in the design of electrical substations because the high potential may be a hazard to people or equipment. The ground potential rise near high voltage substation can be hundreds of volts, even thousands of volts during the ground fault for a short time.

GPR will occur at several locations simultaneously. Fault current will divide among all circuit paths back to the source (metallic and earth return, for example) and create GPRs in the process. Metallic return paths include overhead ground wires, multi-grounded neutrals, bonds, station ground grids, and other conducting materials. Hazardous voltages can appear suddenly as a result of power faults or lightning strikes. Conductive objects (Copper telephone cable, metal, damp saline soils, etc.) can become energized or carry a harmful potential that, if not properly protected, can cause serious injury.

Ground potential rise is also an issue with cell phone base stations. Lightning strokes can hit the base station antenna. And those base stations are also sometimes co-located nearby high voltage electrical lines.

The use of an all-dielectric fiber optic cable in place of a copper telephone cable eliminates the possibility for high voltage to travel from one end of the system to the other. It is of utmost importance to always determine the proper protection scheme when dealing with telecommunication wire line circuits between any location where high voltage and high current equipment is co-located with these circuits. It is always best to design for the worst case situation, since more likely than not, this can happen. Protection against both High voltage and ground potential rise is the best precaution against equipment failures and human injury.

Always when operating with grounding issues remember that there is no absolute ground. There is always a certain amount of resistance to electrical current between all grounding points. This resistance can change with humidity, temperature, connected equipment and many other variables. And there is always a change that some fault current can get to that resistance.


  1. tomi says:

    We’ve seen many videos on Youtube, and even on the news about so called “free energy generators”, but they don’t work period.
    Think of it this way, the most basic laws of physics say that these devices are impossible. Whenever these have been tested in the past they have never worked, if they at first seemed to work they have been shown to be frauds. Laws of physics say that you cannot create energy out of nothing, and I believe that.
    The free energy plans are all scams, and have taken literally millions from people that buy into the carefully crafted lies.

    As a scientific concept, the existence of zero point energy is not controversial although the ability to harness it is. In particular, perpetual motion machines and other power generating devices supposedly based on zero point energy are highly controversial. No device claimed to operate using zero point energy has been demonstrated to operate as claimed. No plausible description of a device drawing useful power from a source of zero point energy has been given. Thus, current claims to zero point energy-based power generation systems currently have the status of pseudoscience or constitute outright fraud.

    Zero point energy is a minimum energy below which a thermodynamic system can never go, thus none of this energy can be withdrawn without altering the system to a different form in which the system has a lower zero point energy. There is no theoretical basis or practical evidence to suggest that infinite amounts of zero point energy are available for use, that zero point energy can be withdrawn for free, or that zero point energy can be used in violation of conservation of energy.

    Information sources:

  2. tomi says:

    You can follow the updates using RSS feed and Twitter.

  3. tomi says:

    Free Magnetic Generator Plans you are referring to do not work.
    Post facts to your site and not misinformation.

  4. Flyg Hotell says:

    greetings! =) im at the office currently, thus i don’t have very much time to write… however! I really enjoyed reading through this article. It turned out to be a bunch of really good stuff. thanks! All the best, Flyg Hotell

  5. Tomi Engdahl says:

    Best practices for bonding and grounding armored fiber cable

    Armored fiber-optic cables are often installed in a network for added mechanical protection. Two types of armoring exist: interlocking and corrugated. Interlocking armor is an aluminum armor that is helically wrapped around the cable and found in indoor and indoor/outdoor cables. It offers ruggedness and superior crush resistance. Corrugated armor is a coated steel tape folded around the cable longitudinally. It is found in outdoor cables and offers extra mechanical and rodent protection.

    Installing armored fiber-optic cable has several benefits, but one inconvenience is the need to bond and ground the cable. This inconvenience can be eliminated by using a dielectric-armored cable

    During some fiber-optic installations there is a need to provide extra protection for the cable due to the installation environment. That environment may be underground or in buildings with congested pathways. Installing an armored fiber-optic cable in these scenarios would provide extra protection for the optical fiber and added reliability for the network, lessening the risk of downtime and cable damage due to rodents, construction work, weight of other cables and other factors.

    An alternative to installing armored optical cable is to place conduit and pull in the fiber-optic cable. However, placing a single-armored fiber cable is usually the more cost-effective choice.

    Proper grounding and bonding is required for the safe and effective dissipation of unwanted electrical current, and it promotes personal and site safety. Typically, fiber-optic systems do not carry electrical power, but the metallic components of a conductive cable are capable of transmitting current. This would occur if a metallic piece of the cable—such as the interlocking or corrugated armor—were to come into contact or close proximity with electrical current from sources such as exposed wiring, faulty electrical systems, lightning or other events. This creates the potential for the occurrence of several hazards, such as electrical shock, fire, damage to electronics and system failures resulting in downtime.

    Bonding and grounding of armored fiber-optic cable are simple steps in the installation process that are often misunderstood or overlooked. The National Electrical Code (NEC) and several industry standards have been established to promote safe and effective bonding and grounding practices of armored optical cables

    Pert Article 770 of the NEC, a fiber-optic cable containing non-current-carrying metallic components, such as armor or metallic strength members, is considered conductive. This is why conductive fiber-optic cables should be bonded and grounded as specified in NEC Article 770.100.

    When all the components of a system are properly bonded together and grounded to the earth, the risk associated with electrical current harming personnel or damaging property and equipment is reduced.

    The first step is to connect/bond the cable armor to a bonding or grounding electrode conductor. This can be accomplished right after the cable is accessed, and the armor is exposed. A bonding conductor or jumper is a short length of conductor, such as copper wire, that maintains electrical conductivity between two metal objects. The bonding conductor is required to be UL-listed and made of either copper or another corrosion-resistant conductive metal

    For the conductive fiber-optic cable to be fully grounded, the bonding conductor from the cable needs to be bonded to the intersystem bonding termination (if present), or another accessible location per NEC Article 770.100. The intersystem bonding termination is the device that connects the bonding conductors to the building’s grounding electrode and ultimately, to earth. Typically this is accomplished by connecting the bonding conductor to a dedicated path back to the telecommunications main grounding busbar (TMGB) or the telecommunications grounding busbar (TGB).

    The dielectric alternative

    If the fiber-optic cable in a system needs extra protection, there is an alternative to using conduit or a bonded and grounded conductive cable, such as an all-dielectric armored cable.

    Because all-dielectric armored cable has no metallic components, there is no need to ground or bond the cable.

  6. fibre optic cable specification says:

    From interfering with all the wire ultimately, an outside protective layer keeps the
    surface atmosphere, for example water or soil.

  7. Tomi Engdahl says:

    Explosion shows effects of an improperly grounded fence

    Ron takes a look at how an explosion at the Escanaba Power Plant substation damaged a fence that was not properly grounded and the steps being taken to properly ground the new fence being installed at the substation.

  8. Tomi Engdahl says:

    6 of 7 Grounding Myths (26min:55sec)

    Learn Grounding Myths in this clip that is part 6 of a 7-part series called Electrical Fundamentals – Protection against electric shoc


    I’ve wondered about some of these issues for over 40 years. Finally, I found these very simple (funny) explanations. Thanks!

    Most modern day electrician have a poor understanding of electricity or at least how to explain it to the customer. So they offer parables and dumb down the understanding to the general public.

    WOW !!! I am really surprised… You just change my mind about grounding. THANK YOU SO MUCH.

    During my time in the telecom industry I was told all of these myths and more. Those “instructing” us were adamant about the “practices”. NONE of them had any idea what they were talking about but were passing this misinformation along over many years in a sort of “good faith”—all the while being blind and leading more of the blind down the same path. I imagine what faulty information was propagated by uneducated persons—who tend to “make something up” which seems to be right. In turn this misinformation is passed along, twisted even further and 50 years later bears no resemblance to fact. No wonder our mechanical trades so full of misinformation.

    This applies to all trades—especially electricity—and welding—which is loaded with BS, myths, misconceptions, guesses and worse. When I learned to weld it was very difficult to find anyone who actually knew the physics of welding in even the slightest way.

    This is the first sensible explanation I’ve ever seen concerning ground. I have heard all these myths before–and they are all wrong!!

    Best explanation of grounding ever!

    Great information.

    Grounding – Safety Fundamentals (1hr:13min:19sec)

  9. Tomi Engdahl says:

    Grounding PV – Grounding Electrode System, NEC 2014 – 690.47 (34min:01sec)

    Grounding Electrode System with code expert Mike Holt in this excerpt from his best-selling library – Solar Photovoltaic Systems DVD program.

  10. Tomi Engdahl says:

    Ground Resistance Measurement, Fall potential method

    In this demonstration we show how to install your earth spikes and why they should be installed correctly. Using a digital resistance meter we demonstrate the importance of depth and spacing of the earth spikes in the ground to obtain the best results with least resistance.

  11. Tomi Engdahl says:

    Earthing Systems for Outbuildings

    Considerations for what type of earth connection to use when connecting power to a shed, garage or other outbuilding.

    Types of Earthing System for Electricity Supplies (UK)

    The three main types of earthing for mains electricity supplies to buildings in the UK. TT, TN-S and TN-C-S.

  12. Tomi Engdahl says:

    Loop Impedance

    Loop impedance, why it matters and typical values.

  13. Tomi Engdahl says:

    Lightning Protection Design, Earthing System Design Lightning Protection for Buildings Design

    Lightning Protection Consultants India provides lightning protection design, earthing system design and grounding system design for buildings

  14. Tomi Engdahl says:

    AEMC® – Understanding Ground Resistance Testing

    This video is an introduction to grounding systems. Our goal is to provide you with a good basic understanding of why grounding is important, the environmental factors to consider when designing a grounding system, and the testing required to ensure your grounding is properly installed and performing to specifications.

  15. Tomi Engdahl says:

    Megger test

    Earth resistivity testing in Cranbrook

  16. Tomi Engdahl says:

    Electrical testing measuring external earth fault loop impedance Ze

    Student trading aid for testing for external earth fault loop impedance Ze using a MFT Megger tester. Please note this test is carried out with only the external earth path in circuit. Includes a full demonstration on how to carry out an earth fault loop impedance test of a single phase installation.

  17. Tomi Engdahl says:

    Earth Electrode Testing

    Testing earth electrodes to ensure their impedance is low enough.

  18. Tomi Engdahl says:

    Grounding – Ground Resistance Measurement, 250.53(A)(2) (26min:27sec)

    This real world test will be conducted by Nationally recognized Code Expert Mike Holt and electrical utility professional Joe Symmes using a 3 pole fault potential method, a clamp on meter to check the ground, an Amp meter to measure the current flow in the event of a ground fault and a volt meter and also test the test potential.

    Mike is nationally recognized as one of America’s most knowledgeable Code Experts and electrical trainers. His instruction has helped tens of thousands of electrical professionals ensure that the proper design and installation of electrical systems are in accordance with the NEC. His dynamic and animated teaching style is relaxed, direct and enjoyable.

  19. Tomi Engdahl says:

    The Megger DET14C and DET24C Clamp On Meters

    DET Earth/Ground Clamp-on Testers

    The new DET14C and DET24C are advanced new earth / ground clamp-on testers that set new standards in terms of access, features, simple operation and safety.

  20. Tomi Engdahl says:

    Grounding Mats for Step and Touch Voltage Protection

    Originally presented at the 2015 Purdue Underground Corrosion Short Course, this video covers the essentials of using gradient control mats to address over-voltage concerns from touch and step potentials.

  21. Tomi Engdahl says:

    External earth loop impedance (Ze) test

    For many installations the resistance of the earth electrode can be measured using an earth fault loop impedance test instrument.
    This test is explained in the video.

    Loop Impedance

    Loop impedance, why it matters and typical values.

  22. Tomi Engdahl says:

    Earth Fault Loop Impedance Test & Prospective Fault Current Test

    Trade Skills 4U tutor Andy Summers talks you through earth fault loop impedance and prospective fault current testing.

  23. Tomi Engdahl says:

    Grounding – Objectionable Current, NEC 2014 – 250.6 (29min:14sec)

  24. Tomi Engdahl says:

    Pretty simple rule: Neutral is connected to ground ONE PLACE per system. That place is where the system begins (meter, or transformer).

  25. Tomi Engdahl says:

    2017 NEC – Equipotential Bonding [680.26], (20min:51sec)

    Swimming Pool Equipotential Bonding 1 of 3 Stray Voltage, (1hr:34min:27sec)
    Swimming Pool Equipotential Bonding 2 of 3, NEC 2014 – 680.26, (19min:50sec)
    Swimming Pool Equipotential Bonding [Part 3 of 3, Testing], (28min:39sec)

  26. Tomi Engdahl says:

    Grounding – Ground Resistance Measurement, 250.53(A)(2) (26min:27sec)

    This real world test will be conducted by Nationally recognized Code Expert Mike Holt and electrical utility professional Joe Symmes using a 3 pole fault potential method, a clamp on meter to check the ground, an Amp meter to measure the current flow in the event of a ground fault and a volt meter and also test the test potential.

  27. Tomi Engdahl says:

    Earth Terminal Voltage Drop TN-C-S

    How the earth terminal on a TN-C-S supply can be at a different voltage to the true Earth.

    As the neutral and earth conductor are combined outside the installation, current in the neutral causes a voltage drop, which results in the earth terminal having a different potential (voltage) to the true Earth outside.

  28. tomi says:

    The Magniwork advertised on your page will not produce free energy.
    It is a false claim that is produces free energy.


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