Lock out/tag out (LO/TO) is required by which organization?

• A. OSHA
• B. NFPA
• C. UL
• D. NEC

Answer: (A)

Lockout/tagout is a safety procedure used to control hazardous energy during maintenance, preventing unexpected machine startup or release of stored energy. The organization that requires it is OSHA, which enforces 29 CFR 1910.147, the standard for the control of hazardous energy. This rule mandates de-energizing equipment, applying locks or tags, and verifying energy isolation before work begins. It applies to most general industry workplaces in the United States, with state plans that mirror OSHA. The other organizations—NFPA, UL, and NEC—deal with codes, product safety testing, and electrical installation standards, but LO/TO requirements come from OSHA rather than these groups. NFPA 70E provides electrical safety guidance that complements OSHA practices, but does not replace OSHA’s mandatory LO/TO rule.