Full definition
Procedure for locking out and tagging hazardous energy sources before maintenance on equipment. Energy types controlled: electrical, pneumatic, hydraulic, mechanical (springs), gravitational, thermal, chemical. Steps: identify sources → isolate → lock with personal padlock → tag → verify zero energy (attempt startup). Standards: NOM-004-STPS, OSHA 29 CFR 1910.147. LOTO failures account for 10% of industrial fatalities in the US and Mexico.