NFPA 70E/CSA Z462 – Workplace Standard for Electrical Safety
NFPA 70E/CSA-Z462 -The standard for electrical safety in the workplace
As the foremost consensus standard for electrical safety in the workplace, NFPA 70E is the primary resource for employers to use in determining how to comply with OSHA’s electrical safety regulations. It is also used by OSHA and the courts in the investigation of injuries in order to assess whether or not the involved employers took reasonable steps and precautions to protect their employees.
The 70E standard was developed in the U.S., but has been largely adopted in Canada’s CSA Z462 ‘Workplace Electrical Safety’ standard and is also increasingly recognized and used in Mexico. The key elements summarized below will generally apply in all three countries. Consult the standards for complete details.
Electrical Safety Program
Employers are required to maintain a documented electrical safety program to direct employee activities in a manner appropriate for the different voltage, energy level, and circuit conditions that may be encountered. The program must address inspections, maintenance conditions, employee awareness, electrical safety procedures, risk assessment and control, job planning and communication, incident investigations, audits, and lockout/tagout.
Risk control methods are to be implemented according to the following hierarchy, which clearly indicates that eliminating the potential hazard should be the first priority, while using PPE to protect against it as the last line of defense.
- Engineering Controls
- Administrative Controls
If work on or near energized electrical conductors and circuit parts operating at 50V or more is required, the safety program must:
- Include procedures that define requirements and provide guidance for workers as they perform work on or near live parts.
- Identify the hazard/risk evaluation procedure to be used before work is started within the limited approach boundary of energized electrical conductors and circuit parts.
- Include a job briefing process to inform employees of the hazards, proper procedures, special precautions, energy source controls, and PPE requirements.
Employees who may be exposed to electrical hazards must be specifically trained to understand the hazards associated with electrical energy as well as the safety-related work practices and procedures required to provide protection from them. The level of training an employee receives determines the tasks he/she is qualified to perform.
Only ‘Qualified Persons’ may perform work on or near exposed and energized electrical conductors or circuit parts. The training requirements include:
- Recognizing the potential hazards that exist
- Distinguishing energized from non-energized parts
- Determining the voltage of exposed energized electrical conductors
- Understanding the relationship between the hazard and potential injury
- Hazard/risk assessment and control methods
- Selecting appropriate personal protective equipment
- Specific work practices and procedures to be followed
- Lockout/tagout procedures
- Emergency procedures for assisting victims of electrical incidents
- Determining approach and flash protection boundaries
The most effective way to prevent electrical injury is to completely remove the source of electrical energy and eliminate the possibility of its reappearance. To do so, workers must identify and disconnect all possible sources of electricity and employ effective lockout/tagout procedures.
Process of Establishing and Verifying an Electrically Safe Work Condition
- Identify and locate all possible sources of electric supply. Care should be taken to identify possible secondary sources.
- Properly interrupt the load current(s) and open the disconnecting device(s). Not all disconnecting devices are rated to interrupt load currents; this should only be done with a properly rated device.
- Verify deenergization through visual inspection of the disconnect contacts. Disconnecting means may sometimes fail to open all phase conductors when the handle is operated, so it is necessary to verify physical contact separation. If this requires removing the disconnect door or cover, appropriate PPE must be used.
- Release stored electrical energy.
- Release or block mechanical energy.
Apply lockout/tagout devices. This should be done in accordance with a formally established company policy.
Use an adequately rated portable test instrument to test each conductor to which the worker may be exposed in order to verify deenergization. The voltage detecting device must be functionally tested both before and after
taking the measurements in order to ensure that it is working satisfactorily.
Circuit parts with induced voltages or stored electrical energy must be grounded. If the conductors being deenergized could contact other energized conductors or circuit parts, temporary grounding devices rated for the available fault duty should be applied.
- A description of the circuit and equipment to be worked on and its location
- A description of the work to be performed
- Justification for performing the work in an energized condition
- A description of the safe work practices to be employed
- Results of the shock risk assessment
- Determination of shock protection boundaries
- Results of the arc flash risk assessment
- The flash protection boundary
- The personal protective equipment required for worker safety
- Restricted access of unqualified persons from the work area
- Evidence that the job briefing has been completed
Shock Risk Assessment and Approach Boundaries
A shock risk assessment must be performed to determine the extent to which shock hazards exist and the associated required protective measures. Because personnel will approach energized electrical conductors or other live circuit parts, limited and restricted approach boundaries must be determined in order to identify safe approach distances and the precautions required to minimize the possibility of shock. These boundaries are described in the illustration in the left margin and can be determined from tables in the standard.
Arc Flash Risk Assessment
An arc flash risk assessment shall also be performed by a qualified person in order to determine the level of risk and any precautions that are required to protect personnel from the possibility of being injured by an arc flash. As part of this analysis, flash protection boundaries must be determined based on available bolted fault currents and the incident energy exposure level for personnel working within this boundary must be calculated.
Personal and Other Protective Equipment
Employees working in areas where electrical hazards are present must be qualified to perform the work and must be provided with, and use, protective equipment designed and constructed for the specific part of the body to be protected and for the work to be performed. Personal Protective Equipment (PPE) requirements can be determined from tables in the standard, based either on the calculated incident energy level or on the PPE category assigned to the type and electrical energy characteristics of the equipment being worked on. Four categories of increasingly protective PPE are defined and specified for use with the various types of equipment.
Energized Work - Normal Operation
Normal operation of electric equipment shall be permitted where the equipment; is properly installed and maintained; used in accordance with instructions included in the labeling and listing, and included in the manufacturer’s instructions; doors are closed and secured; covers are in place and secured; there is no evidence of impending failures.
MELTRIC Switch-Rated plugs and receptacles simplify NFPA 70E and NEC compliance by eliminating the possibility of exposure to energized parts and arcing when making and breaking the electrical connections required to change-out motors and other equipment. Our devices eliminate arc flash at disconnection and protect users from other electrical hazards, including shock and burns.
Pin and sleeve and twist type devices are not intended to be connected or disconnected under load. Doing so may expose users to live contacts and arc flash hazards that can result in serious injuries. However, MELTRIC Switch-Rated devices are engineered for safety and can be safely made and broken under full load, without the need for PPE or additional safety precautions. Built-in provisions make OSHA-compliant lockout/tagout fast and easy.
Here's how MELTRIC makes NFPA 70E and NEC compliance easy:
Establishing and Verifying an Electrically Safe Work Condition - Article 120.5
Switch Ratings ensure a safe and proper interruption of the load current (2); Removal of the plug from the receptacle provides clear visual and physical verification of de-energization (3) and (7); and integral lockout provisions make applying lockout/tagout simple (6).
Normal Operation - Article 130.2 (A)(4)
PPE isn’t required when making and breaking electrical connections with MELTRIC Switch-Rated plugs and receptacles; these products meet the NFPA 70E definition of “Normal Operation.”
NEC Line-of-Sight Motor Disconnect - Article 430.102(B) (1) and 430.109 (A)(1), 430.110
MELTRIC Switch-Rated plugs and receptacles are horsepower-rated and UL/CSA listed for motor circuit disconnect switching; they meet all NEC requirements as an approved line-of-sight motor disconnect. These switch ratings eliminate the need for the auxiliary disconnect required with most other plugs and receptacles.