At what minimum voltage must live parts of electrical equipment be guarded?

The correct choice is that live parts of electrical equipment must be guarded at a minimum voltage of 50 volts. This standard is critical for ensuring safety in electrical installations. At voltages above this threshold, the risk of electrical shock or arc flash increases significantly, posing a serious hazard to workers and anyone who might come into contact with unguarded live parts.

The 50-volt mark is recognized based on various safety standards, including those outlined by the National Electrical Code (NEC) and OSHA regulations, which aim to protect individuals from potentially life-threatening electrical shocks. Equipment operating at voltages above this level necessitates specific guarding measures to mitigate risks, such as insulated barriers or enclosures, to prevent accidental contact.

Lower voltage levels, such as 30 volts, 40 volts, and 60 volts, do not hold the same level of risk and may not require the same strict guarding measures as those mandated for 50 volts and above. This distinction is vital for compliance with safety regulations and ensuring proper safeguards are in place in workplace settings.