Red Seal Electrician Practice
Wiring and componentsQuestion 10 of 1506

Why are electromechanical relays often preferred over solid-state relays where safety matters?

  1. Electromechanical relays switch faster than solid-state devices
  2. A fail-open state is generally safer than a fail-closed state
  3. Electromechanical relays have no moving parts to wear out
  4. Electromechanical relays isolate better than optical coupling
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Correct answer: A fail-open state is generally safer than a fail-closed state

Open contact failures are usually safer than a load that cannot be switched off.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 5.5: Solid-state Relays

Practice wiring and components

Questions last reviewed: 18 October 2026