Which activities are covered
NOM-029-STPS-2011 is listed as current and applies to maintenance of permanent or temporary electrical installations in Mexico. It covers overhead and underground lines and work involving energised parts under its specific conditions. It does not indiscriminately authorise every form of intervention.
The electrical risk entry explains the general hazards. This standard adds work organisation, documentation, competence, procedures and equipment. Compliance with installation design requirements does not replace the preparation needed to maintain that installation safely.
Work plan and installation information
The workplace needs a work plan and an updated single-line diagram, with the relevant load information. The plan identifies activities and local hazards, including adjacent equipment, other operations and planned switching or related movements.
For example, an extension introducing another supply can make the diagram used by maintenance obsolete. Documentation must reflect the actual installation before it is relied upon to define controls. Incomplete identification can affect people who are not even involved in the initial intervention.
Competence and equipment control
Activities are performed by trained personnel using specific procedures. The standard requires written authorisation for particular work, including height, confined spaces, substations and live parts. Authorisation is connected to the activity and preparation, rather than informal confidence in the worker.
Tools, equipment and insulating implements require appropriate selection, inspection, care and replacement. Appearance alone does not demonstrate suitability for the voltage or working conditions. Personal protection is integrated with installation controls rather than replacing them or making every situation acceptable.
Coordination, emergencies and records
Procedures must address energy control and safe verification of installation conditions by competent personnel. This entry does not reproduce an intervention sequence because omission of a situation-specific condition could make it dangerous.
Employers must also supervise contractors, communicate risks and maintain an emergency plan. Records identify responsible people, activities, results and maintenance dates. Work closeout should clarify handover conditions and the information needed by those returning the installation to use. The documentation must describe what was actually done, including unresolved abnormalities, rather than merely recording that a maintenance visit occurred.
