【Daily Topic】【Electrical Edition 20160826】
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Participation reward: 2 Wealth. Reward for the correct answer: 9 Wealth. Which of the following statements is correct? ( ) A. In power circuits with a directly grounded neutral point that are used specifically at construction sites, a TN-C neutral protection system must be employed. B. The bases of insulators, the flanges of bushings, protective nets (covers), and busbar supports, as well as other accessible exposed conductors, must be reliably grounded (PE) or connected to the neutral (PEN). It shall not be used as a connecting conductor for grounding (PR) or bonding to neutral (PEN). C. When a regular copper wire is used as the protective conductor, its cross-sectional area shall be no less than 2.5 mm² when mechanical protection is provided; it shall be no less than 5 mm² when no mechanical protection is available. D. Metal cable supports and cable conduits must be reliably grounded (PE) or bonded to neutral (PEN). Correct answers: BD
The correct statements are (BD). A. In power circuits with a directly grounded neutral point that are used specifically at construction sites, a TN-C neutral protection system must be employed. B. The bases of insulators, the flanges of bushings, protective nets (covers), and busbar supports, as well as other accessible exposed conductors, must be reliably grounded (PE) or connected to the neutral (PEN). It shall not be used as a connecting conductor for grounding (PR) or neutral connection (PEN). C. When a conventional copper wire is used as the protective conductor, its cross-sectional area shall be no less than 2.5 mm² when mechanical protection is provided; it shall be no less than 5 mm² when no mechanical protection is available. D. Metal cable supports and cable conduits must be reliably grounded (PE) or connected to the neutral (PEN)
B. The bases of insulators, the flanges of bushings, protective nets (covers), and busbar supports, as well as other accessible exposed conductors, should be reliably grounded (PE) or connected to the neutral (PEN). It shall not be used as a connecting conductor for grounding (PR) or neutral connection (PEN). D. Metal cable supports and cable conduits must be reliably grounded (PE) or connected to the neutral (PEN)