IEEE Grounding Recommendations

The IEEE (Institute of Electrical and Electronics Engineers) is a professional association that promotes the educational and technical advancement of electrical and electronic engineering, telecommunications, computer engineering and allied disciplines. It has 13 “color books” that provide standards for electrical applications, including standards on the design of electrical system grounding, the calculations to be used when designing utility line grounding, and testing methods. Read on to find out more about IEEE grounding recommendations as outlined in these ‘color books’.

About Grounding Electrical Equipment

Grounding electrical equipment is a good idea for several reasons. It protects personnel and equipment from overvoltages, faults and lighting. It also provides a solid reference to earth, keeping system voltages stable and establishing a reference to control electrical ‘noise’ that can interfere with the proper operation of electrical equipment.

When we talk about grounding, we can refer to a few different things. It is important to differentiate between which application we are referring to when discussing the testing of grounding so that the proper tests and analysis can be completed.  These different types of grounding include:

  •         Establishing the grounding electrode system (earth reference)
  •         Bonding metallic parts to create a continuous circle that is at earth potential
  •         To provide a low impedance equipment grounding conductor that can conduct an adequate current during a fault to ground and allow overcurrent devices to operate.

There are several standards that must be followed when grounding electrical equipment. Practices for various types of grounding and the testing of grounding are outlined in many of the Color Books as mentioned below.

IEEE’s Color Book’s Grounding Recommendations

The IEEE has several books that offer different advises concerning grounding recommendations. The IEEE 1100 is also known as the Emerald Book and it outlines the practices for the powering and grounding of electronic equipment. IEEE 142 is the Green Book and it gives proposed practices for the grounding of industrial and commercial power systems only, including an earth resistance in the range of ½ to 5 ohms.

IEEE’s Color Book’s Electrical Stations and Substations

The IEEE also has color books for the grounding of electrical stations and substations. The IEEE 1246 gives guidelines on how to temporarily grounding of electrical substations that originates in the Substation Safety Working Group WGE4.

The IEEE 837 lists the permanent connection that is permitted in substation grounding. The IEEE standard 367 describes the practices for determining power station ground potential rise and induced voltage in the case of a power fault. These calculations include the GPR (ground potential rise) and LI voltage (longitudinal induction). The IEEE 367 also gives recommendations on how to lower these values if they are too high.

The IEEE 80 has a list of safety measures that can be taken during alternating current substation grounding. It has values of ½ to 1 ohm for generating plants and large substations. IEEE 665 once provided the guide for generating station grounding but has since been withdrawn as the standard.

The IEEE 487 has recommended practices on how to protect wire line communications, including telephone wires for electrical supply locations. IEEE std 1050 is the association’s guide for grounding instruments and control equipment that is located in power-generating stations.

IEEE Color Book’s Ground Wire Standards

The IEEE 1591.1 is the standard for the performance of OPGW (optical ground wire), also known as shield or earth wire. The IEEE 1138 is where you can find the standard for mechanical properties and testing when OPGW is used in utility power lines.

Testing, that is also common in grounding applications, includes the grounding electrode, water pipe, Ufer system, ground ring and ground rods (or ground grids). Applicable standards are outlined in the IEEE 81 and IEEE 81.2. The “Three Point Fall of Potential” procedure is the most common testing method which if offered in IEEE 81. This is adequate for systems that are relatively small and have an earth resistance greater than 1 ohm. For large grids and systems that require a ground resistance of less than 1 ohm, the IEEE 81.2 standard should be considered.

IEEE 81.2 offers a standard on the measurement of the impedance of connected grounding systems but that was since withdrawn. However, the IEEE 81-1983, which is the guide for measuring earth resistivity is still active. The IEEE 524 gives recommendation for installing overhead transmission line conductors and ground wires safely.

IEEE’s Color Book for Neutral Grounding of Utility Power Systems

The IEEE C62.92 series addresses neutral grounding in electrical utility power systems. C62.92.1 provides the introduction to the C62.92 standard family. It contains subsections which cover different parts of the electrical utility system.

The IEEE 62.92.3 outlines the grounding generator auxiliary systems. IEEE C62.92.4 applies to 2.3-34.5 kV Ac distribution system grounding. C62.92.5 covers the neutral grounding of the sub-transmission systems. These standards are set by the surge protective devices and high voltage oversight committee.

Related Grounding Standards

The IEEE uses the standard 32 by the American National Standards Institute to define the terminology and test procedures that apply to neutral grounding devices. IEEE C37.101 gives the recommendations for generator ground protection but does not include how to select a generator or connect it to a grounding device.

IEEE C37.20.6 is the standard for 47.6 kilovolts to 38 kilovolts rated ground devices as well as test devices used in enclosures. IEEE 57.13.3 describes the practices for grounding instrument transformer secondary circuits. IEEE 1048 gives recommendations for grounding power lines.

The IEEE Color Books can be useful to those who work in the electrical industry. A familiarity with these books can be helpful in providing valuable information pertaining to their professions. These books are available for purchase on the internet and are widely accessible to anyone looking for information that they contain.