Mexican Standard NOM-022-STPS-2015

• The document concerns the Official Mexican Standard NOM-022-STPS-2015, which deals with static electricity in workplaces and sets out safety conditions
• The standard is issued by the Ministry of Labor and Social Welfare

Key Articles Referenced

• Article 40, sections I and XI, of the Federal Public Administration Organic Law
• Articles 512, 523, section I, 524, and 527 of the Federal Labor Law
• Sections of the Federal Law on Metrology and Standardization

Purpose of the Standard

• It aims to establish safety conditions in workplaces to prevent risks associated with static electricity and atmospheric electrical discharges

Scope of Application

• Applies to areas in workplaces where flammable or explosive substances are stored, handled, or transported
• Also applies where processes, materials, and equipment can generate static electrical charges
• Does not apply to vehicles, trains, ships, or aircraft used for transportation regulated by the Secretariat of Communications and Transportation

Key Definitions

• Static Electrical Charge: The physical property of matter due to loss or gain of electrons, typically in insulators or isolated conductors
• Grounding: Connecting equipment or circuits to an electrode or grounding system to achieve zero electrical potential
• Lightning Current: Current that flows at the point of contact between lightning and the earth or a protective system
• Electrical Discharge: Current flow between two bodies with a potential difference, breaking the dielectric of the air
• Atmospheric Electrical Discharge: Transfer of electrical charges between clouds or between a cloud and the earth
• Static Electricity: Electrical charges generated and stored in solids, particles, or fluids
• Grounding Electrode(s): Metal element(s) buried to establish an electrical connection to the earth
• Lightning Rod: Metallic elements providing an impact point for atmospheric discharges
• Grounding System: A network of conductors, connections, electrodes, and accessories designed to drain lightning and static charges to the earth
• System for Protection Against Atmospheric Electrical Discharges: A set of elements to protect an area from atmospheric discharges, comprising external and internal systems

Employer Obligations

• To establish safety conditions to control static electricity generation/accumulation as per Chapter 7 of the standard
• To install a protection system against atmospheric electrical discharges where flammable or explosive substances are handled, stored, or transported, as per Chapter 8
• Regularly measure the resistance to ground of the grounding system, check continuity, and measure relative humidity if it's a control measure
• Inform employees and the Safety and Hygiene Commission about the risks of static electricity and how to prevent them
• Train employees on techniques to discharge or avoid static electricity accumulation, as per Chapter 10
• Maintain records of grounding resistance, electrical continuity, & relative humidity
• Provide the authorities with all required information

Employee Obligations

• Comply with safety measures outlined in the standard and established by the workplace
• Participate in training provided by the employer
• Report any abnormal conditions in grounding and lightning protection systems

Safety Conditions for controlling static electricity

• Must be determined by the nature of work, features of substances, environmental conditions, characteristics of construction materials
• Install grounding systems, devices, or equipment, like ionizers, neutralizers, grounding devices, static electricity dissipation bars, etc
• Ensure electrical bonding between machines, equipment, containers, and metallic components

Grounding System Measurement

• The measurement must be done at least every twelve months
• Must have a resistance of less than or equal to 10 ohms for resistance to earth of electrodes in lightning rods or lightning protection systems
• Must have has a resistance of less than or equal to 25 ohms, for the resistance to earth of the grounding network
• Electrical continuity at connection points of equipment that may generate or store static electricity to exist

Humidification of the environment

• Humidify the environment, maintaining a relative humidity above 65%
• If closed, workplace must maintain humidity above 65%, measuring and recording values at least every 12 months
• The measurement equipment must be up to date and calibrated
• Equipment should be recalibrated, according to federal law

Lightning Protection Systems

• Workplaces classified as high fire risk must install a lightning protection system (lightning rods)
• The electrical earthing systems should interconnect with other earthing networks and be disconnectable for testing

Training Requirements

• Provision of training regarding generating and accumulating static electricity
• Knowledge on installation and maintenance of systems
• Training on properly wearing protective equipment

Verification Units and Testing Labs

• Employers can contract verification units and/or testing labs accredited and approved
• The validity of the verification report and result is one year if conditions remain unaltered

Conformity Assessment

• The evaluation done physically, documented or through interviews
• Evaluation requires checking the elements of the system, proper installment and proper grounding

Electricity Static Guide

• The guide is non-mandatory but serves as guidelines to accident prevention
• Equipment needing static control includes, rolling objects, ventilation products, and painting equipment