Red Seal Electrician Practice
Motor controlsQuestion 32 of 1506

A pushbutton must now turn a lamp off when pressed, instead of on. The lamp is driven by a PLC. What is the easiest change?

  1. Replace the PLC output module with one that has a normally closed output
  2. Rewire the lamp across L1 and L2 in series with the pushbutton switch
  3. Change the program contact from normally open to normally closed
  4. Move the Common terminal of the PLC from the neutral over to L1
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Correct answer: Change the program contact from normally open to normally closed

In a PLC the logic is software, so a program edit replaces a hardware change.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.6: Programmable Logic Controllers (PLC)

Practice motor controls

Questions last reviewed: 18 October 2026