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Grounding Electrode — A conducting object through which a direct connection to the earth is established. Section 250.52(A)(1–8) lists the permissible grounding electrode options. While all the available grounding electrodes are required to be bonded per 250.50, it’s fair to say the most common are typically rod and pipe electrodes
This practice is called “grounding” and it is done to limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and to stabilize the voltage to earth during normal operation as documented by 250.4(A)(1) of the Code.
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- Tion 250.53(A) Rod, Pipe, and Plate Electrodes
- 53(A)(1) Below Constant Moisture Level
- 53(A)(2) Supplemental Electrode Required
- 53(A)(3) Supplemental Electrode
- 53(A)(4) Rod and Pipe Electrodes
- Tion 250.53(B) Electrode Spacing
- Tion 250.53(C) Bonding Jumper
- Tion 250.53(D) Metal Underground Water Pipe
- Tion 250.53(E) Bonding Jumper Size For The Supplemental Grounding Electrode
Rod, pipe, and plate grounding electrodes must meet the requisites of sections 250.53 (A)(1) through (3) and be free from nonconductive coatings.
Bury the rod, pipe, or plate’s upper end in a soil stratum with permanent moisture, if attainable, and submerge the electrode entirely unless the soil condition averts such installation – apply Section 250.53(A)(4) for options. See Figure 1. Moisture content is a typical approach to controlling soil resistivity. The electrode’s ground resistance, u...
Add an electrode–selected from the types depicted in sections 250.52(A)(2) through (8)–to single rods, pipes, or plates unless they have a measured resistance to the ground not higher than 25 Ω (see Figure 1). Bond the additional electrode to one of the following: 1. Directly to the rod, pipe, or plate electrode 2. Grounding electrode conductor 3. ...
Set apart the supplemental rod, pipe, or plate a minimum of 1.8 m. According to the Informational Note in this section, the paralleling efficiency of ground rods increases by separating them twice the length of the most extended rod. Figure 2 shows a ground rod supplying current to the earth. There are infinite imaginary layers around the rod, each...
The electrode must be installed straight down for at least 2.44 m in length, contacting the soil. Connecting a 2.44-long rod above the ground surface will not comply with the rule. Where encountering rock bottom, the electrode may be pushed at an oblique angle not to exceed 45° from a vertical line–keeping at least 2.44 m of its length inside the g...
Maintain a minimum separation of 1.83 m between any electrodes of the types specified in sections 250.52(A)(5) or (7)–rod, pipe, or plate electrodes–when used on different grounding systems. An example is a grounding electrode for power and light separated from a grounding electrode connected to a strike termination device (see Figure 5). In practi...
The bonding jumpers connect the grounding electrodes to form the grounding electrode system. The rules are: 1. Install by sections 250.64(A), (B), and (E) 2. Size by Section 250.66 3. Connect as specified in Section 250.70 4. Do not use rebar as a conductor to interconnect the electrodes Example 1. Determine the bonding jumper sizes in Figure 6. Us...
The underground metallic water pipe used as a grounding electrode should meet the following: 1. Ensure the continuity of the grounding path or the bonding connection to the interior piping does not depend on meters, filters, or the like. Figure 8 shows a water meter and filter bypassed via bonding jumpers. This rule avoids the loss of grounding if ...
When the supplemental electrode is a rod, pipe, or plate, the size of the bonding jumper dedicated solely to the supplemental electrode does not need to be larger than 6 AWG in copper or 4 AWG in aluminum. See the bonding jumper in Figure 9.
May 21, 2021 · Do you know what the grounding electrode system is and why it is important for electrical safety? Learn from the experts at NFPA how to identify and understand the eight items that form this system, and how they are regulated by the NFPA codes and standards. Read this informative blog post and discover more about our electrical world.
A grounded conductor (may be a neutral) is grounded at the source and at the service. Some separately derived systems are required to be grounded. The grounded system conductor is generally required to be isolated (insulated) downstream from the service and source of a separately derived system.
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Nov 7, 2022 · Section 250.1. This section explains that Article 250 focuses on general grounding and bonding electrical installation requirements, including: The grounding of systems, circuits, and equipment. Which circuit conductor must be grounded. Where to locate the grounding connections.
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Methods of making an earth connection of the metal frame of the building or structure are described. Requires direct contact with the earth, concrete encasement or by connection to concrete encased grounding electrode. Once a recognized grounding electrode, it can be used to bond other electrodes. 12.
