Interlock (Engineering)

> Defeatable interlocks are allowed on electrical equipment up to 600 volts.

Fun fact, "high voltage" starts at 600v according to many regulatory bodies. 1kv is another popular threshold.

The blast pressure from an arc can get to a point where protective gear is irrelevant. Copper expands something like 30000x when it vaporizes.

    E - Establish (Identify all sources)
    S - Switch (Disconnect)
    V - Verify (Visually check, if possible)
    R - Release (Stored energy)
    L - Lockout/Tagout
    T - Test (Absence of voltage)
    G - Ground (If necessary)
    Renergize - Re-energizing Equipment

Type systems, database normalisation, reactive programming (i.e.: non-manual state management), or more generally making illegal states unrepresentable are the software equivalents!

> In modern days, most cars have an anti-theft feature that restricts the turning of the steering wheel if the key is not inserted in the ignition

This needs updating:

> In the past, most cars had an anti-theft feature that restricted the turning of the steering wheel if the key was not inserted in the ignition. These days, for convenience, is enough that the key has been in the vicinity of the car in the recent past.