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Security Fundamentals & Crypto · Foundational

Fail-Safe

Failure mode that defaults to a state protecting human life, often unlocking doors when power fails.

Definition

In physical security, a fail-safe lock releases when it loses power so people can exit during emergencies such as fires. In some engineering contexts fail-safe means failing to the least harmful state. On security exams, fail-safe is contrasted with fail-secure, and life safety always takes precedence.

Example

Magnetic door locks on a building's emergency exits release when the fire alarm triggers or power is lost.

Exam tip

If the question involves people's safety, the fail-safe option is correct; know that terminology varies by source.

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