UNIT 3 Grounding Electrode System and Grounuimg Which of the following statement
ID: 3348942 • Letter: U
Question
UNIT 3 Grounding Electrode System and Grounuimg Which of the following statements about grounding electrodes is true? a. An undergr 6. round metal water pipe electrode is required to be supplemented by another grounding electrode. b. A concrete-encased electrode is required to be supplemented by another grounding electrode. cAn 8 ft (2.5 m) ground rod with a resistance of 24 ohms is required to be supple- mented by another grounding electrode. Two ground plate equired to be supplemented by another grounding electrode. d. grounding electrodes that are installed 6 ft (1.8 m) apart are 7. Which of the following statements about the installation of a ground rod is correct? vertically if practicable, then at not more than a 45-degree angle if not prac- or arid regions, it is required to install rods that are longer than 8 ft to reach c. First measure the resistance of the first ground rod, and install additional rods until d. It is permitted to install the rod vertically at not more than a 45-degree angle or in a a. Install ticable to install vertically, then in a ditch at least 212 ft(750 mm) deep if not practicable to install at not more than a 45-degree angle. permanent moisture level. the resistance of the group is 25 ohms or less. ditch at least 21g ft (750 mm) deep, at the installer's option.Explanation / Answer
NEC Guidelines based questions. I won't be explaining much here.
6). A
Per NEC guidelines for grounding electrode system, an underground metal water pipe shall be supplemented by another grounding electrode. In rest of the given options, additional grounding electrodes are not required.
Also, note that if a single rod, pipe or plate electrode is installed it shall be supplemented by additional electrode. However, if the single rod, pipe or plate has a resistance to earth of 25 ohms or less then, additional electrodes are not required.
7). A is true.
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