Kiểm tra & Khắc phục sự cốCâu 511 / 521
A non-contact voltage tester (NCVT) does not light up near a conductor you must work on. Before treating the conductor as dead, what is the correct action?
a.Trust the NCVT completely and begin work
b.Assume the conductor is a neutral and cut it
c.NCVTs are infallible, so no further check is needed
d.Confirm de-energization with a contact voltage tester using live-dead-live, since NCVTs can miss voltage (shielding, ganged wires, low sensitivity)
Giải thích
An NCVT is only a first indicator; it can fail to detect voltage due to shielding, cable geometry, or dead batteries, so it must never be the sole basis for calling a conductor dead. Verify with a contact tester using the live-dead-live method before touching conductors. Trusting it blindly (a, c) or guessing it's a neutral (b) can be fatal.
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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