【Daily Topic】【Electrical Edition 20160903】
Thread Content
Participation reward: 2 Wealth. Reward for correct answer: 9 Wealth. Which of the following statements is incorrect? ( ) A. When angle steel is used as an artificial grounding electrode and is laid underground, its minimum thickness is 4 mm. B. For grounding wires buried in the ground, without any anti-corrosion protection but with mechanical protection, the minimum cross-sectional area of the copper conductor is 25 mm². C. For the distribution circuits of hand-held and mobile electrical equipment, residual current protection is advisable, with a tripping current of 30 mA. D. For the distribution circuits of electrical equipment at construction sites, residual current protection is advisable, with a tripping current of 20–50 mA. Correct answers: CD
The incorrect statement is (CD). A. When angle steel is used as an artificial grounding electrode buried underground, its minimum thickness is 4 mm. B. For grounding wires buried in the ground, without any anti-corrosion protection but with mechanical protection, the minimum cross-sectional area of the copper conductor is 25 mm². C. For the power distribution circuits of hand-held and mobile electrical equipment, residual current protection is advisable, with a tripping current of 30 mA. D. For the power distribution circuits of electrical equipment at construction sites, residual current protection is advisable, with a tripping current of 20–50 mA
The incorrect statement is (CD). A. When angle steel is used as an artificial grounding electrode buried underground, its minimum thickness is 4 mm. B. For grounding wires buried in the ground, without any anti-corrosion protection but with mechanical protection, the minimum cross-sectional area of the copper conductor is 25 mm². C. For the power distribution circuits of hand-held and mobile electrical equipment, residual current protection is advisable, with a tripping current of 30 mA. D. For the power distribution circuits of electrical equipment at construction sites, residual current protection is advisable, with a tripping current of 20–50 mA
D. For the power distribution circuits of electrical equipment at construction sites, residual current protection should be installed, with a tripping current of 20–50 mA
The incorrect statement is (CD). A. When angle steel is used as an artificial grounding electrode buried underground, its minimum thickness is 4 mm. B. For grounding wires buried in the ground, without any anti-corrosion protection but with mechanical protection, the minimum cross-sectional area of the copper conductor should be 25 mm². C. For the distribution circuits of hand-held and mobile electrical equipment, residual current protection is advisable, with a tripping current of 30 mA. D. For the distribution circuits of electrical equipment at construction sites, residual current protection is advisable, with a tripping current of 20–50 mA
CD、、、、、、、、、
The incorrect statement is (c).