An toànCâu 432 / 521
Before you rely on a voltage detector to verify absence of voltage, you should:
a.Assume it works if the battery indicator light is on
b.Only test after your hand is already on the conductors
c.Do nothing, because meters never fail
d.Test it on a known energized source before and after the check to confirm it is functioning (live-dead-live test)
Giải thích
A voltage tester must be proven functional on a known live source immediately before and after checking the circuit, so a failed meter cannot fool you into treating a live circuit as dead. A battery light does not prove the tester reads voltage, and touching first defeats the purpose of verification.
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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