Kiểm tra & Khắc phục sự cốCâu 503 / 521
A homeowner reports a 'weird' outlet. Which instrument most quickly indicates common miswires (open ground, open neutral, reversed polarity) at a 120 V receptacle?
a.A megohmmeter
b.A clamp-on ammeter
c.A plug-in receptacle (three-light) tester
d.A phase-rotation meter
Giải thích
A plug-in three-light receptacle tester lights a coded pattern that flags open ground, open neutral, and reversed polarity instantly. A megohmmeter tests insulation, a clamp meter reads current, and a phase-rotation meter is for three-phase sequence, none of which quickly maps outlet miswires.
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- For routine voltage checks at 120 V cord-and-plug receptacle outlets on a branch circuit, what CAT rating is generally the minimum appropriate category?
- You want to measure current with a DMM's internal ammeter function. Which practice is essential to avoid a dangerous fault?
- A conductor with 0.2 ohms of resistance carries 15 A. How much power is dissipated as heat in that conductor?
- Two identical 60 W, 120 V lamps are accidentally wired in series across 120 V. Approximately what voltage will a DMM read across each lamp, and how will they glow?
- You must measure current on a circuit feeding electronic (nonlinear) loads such as LED drivers and VFDs. Which meter feature gives an accurate reading?
- A 6 ohm and a 3 ohm resistor are connected in parallel. What total resistance should an ohmmeter read?
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