Installing
Electrical Grounds
Installing |
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[lesson title] |
| 2-1. Types of Conductors. Three different types of conductors are used to install grounding systems. They are copper, aluminum, and copper-coated aluminum (Figure 2-1).
Figure 2-1. Types of conductors a. Ground conductors are shown in Figure 2-2. If the ground conductor is covered or insulated, the material must be green.
Figure 2-2. Ground conductors
Figure 2-3. Aluminum conductors b. The size of the conductor used between the power panel and the grounding rod is determined by the ampacity of the system being grounded. For a 100-ampere service, the ground conductor must be No. 8 copper or No. 6 aluminum (Figure 2-4).
Figure 2-4. Size of conductor c. When the grounding electrode is a high-capacity grounding system, such as metallic water or piping systems with at least 10 feet of underground pipe in contact with the soil, the system (metallic or piping) must be used as indicated in Table 2-1. d. Metallic water pipe that has 10 feet or more of its length in direct contact with soil must be bonded into the grounding system (Figure 2-5).
Table 2-1. Grounding electrode conductor for alternating current systems
Figure 2-5. Ground conductor installed on a metallic water pipe e. A ground conductor hooked to a metallic water system must be continuous (without splices) from the power panel, the water system, and the grounding rod (Figure 2-6). f. Aluminum or copper-coated aluminum conductors will not be placed closer than 18 inches from the soil. g. Aluminum or copper-coated aluminum conductors will not be placed in direct contact with masonry. When aluminum is placed in contact with soil and masonry, corrosion occurs at an accelerated rate. This corrosion is called electrolysis.
Figure 2-6. Ground conductor hooked to a metallic water system |
| Content provider: U.S. Army, David L. Heiserman Publisher: SweetHaven Publishing Services |
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Revised: April 19, 2005
