Red Seal Electrician Practice
Signalling and communicationQuestion 123 of 1506

In the hypothetical BogusBus, one maker grounds the negative side of its 24 V DC supply and another grounds the positive. Why is this a problem?

  1. The lamps would not light at all because 24 V is too low for them
  2. The transmitter would run at 48 V instead of its rated 24 V
  3. Through the earth grounds, each supply would short the other
  4. The switches would send a serial signal instead of parallel
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Correct answer: Through the earth grounds, each supply would short the other

A standard must also set power supply grounding rules.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 14.2: Networks and Busses

Practice signalling and communication

Questions last reviewed: 18 October 2026