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Safety and work practicesQuestion 740 of 1506

Why was the 4-20 mA standard preferred over the old 10-50 mA standard?

  1. It used AC, which is safer to wire
  2. It used more current to give a stronger and clearer signal
  3. It needed no wiring at all between the transmitter and the indicator
  4. Lower voltage and current meant less shock and spark risk
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Correct answer: Lower voltage and current meant less shock and spark risk

Lower levels mean less danger of shock and of sparks that could ignite flammable atmospheres.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 9.3: Current Signal Systems

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Questions last reviewed: 18 October 2026