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 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.
The OSHA CFR 1910.333 Standard is quite clear about employer’s responsibilities: Section (a) states that “Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized.”
Article 110 of the NFPA70E standard provides helpful guidance on how these and associated other legal requirements in the OSHA Standard can be met.
First Priority: Hazard Elimination
Hazard elimination is specifically identified as the first priority in the implementation of safety-related work practices, and accordingly is the first method listed in the Hierarchy of Risk Control Methods to be employed:
(3) Engineering Controls
(5) Administrative Controls
It is important to note that the use of PPE is indicated as the least effective risk control method. If a hazard can be eliminated, it should be eliminated; there is no risk of injury if hazards do not exist.
Electrically Safe Work Condition
The OSHA CFR 1910.333 Standard also requires in section (a)(1) that “Live parts (above 50V) to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.”
Thus, an employer’s Electrical Safety-Related Work Practices must include the determination of when it is necessary to establish an Electrically Safe Work Condition by disconnecting and isolating the circuit parts to be worked on from the energized circuit.
Energized electrical conductors and circuit parts operating at 50V or more, are required to be placed into an electrically safe work condition before work can begin, if:
- The activity is not a permitted normal operation of energized equipment
- The employee is within the limited approach boundary
- There is an increased likelihood of injury from an exposure to arc flash hazards
Normal Operation of energized electric equipment shall be permitted provided the equipment is properly installed and maintained with no evidence of impending failure; and is being used for its intended function in accordance with the manufacturer’s instructions, labeling and listings, and with any doors or covers closed and secured. Normal operation refers to using the equipment, not working on it.
Justification for Energized Work
Deciding to work on or near energized electrical conductors and circuit parts should be a last resort in the workplace, after all opportunities for establishing an electrically safe work condition have been exhausted. Work on energized parts at 50V or more should only be performed if the employer can demonstrate that deenergizing will introduce additional hazards, or is not feasible due to equipment design or operational limitations.
Electrical Safety Program
Another key work practice requirement is the maintenance of 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, employee awareness and self-discipline, electrical safety principles and procedures, risk assessment and control, job planning, communication, and scope changes, incident investigations, electrically safe work condition policy, lockout/tagout, audits, and documentation.
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’ with appropriate qualifications may perform work on or near exposed and energized electrical conductors or circuit parts. The training requirements include:
- Recognizing and assessing potential hazards and risk control methods
- Distinguishing energized from non-energized parts and determining the voltage
- Understanding the relationship between the hazard and potential injury
- Determining approach and flash protection boundaries
- Selecting appropriate personal protective equipment and tools
- Specific work practices and procedures to be followed
- Lockout/tagout procedures
- Emergency procedures for assisting victims of electrical incidents
The most effective way to prevent electrical injury is to eliminate the hazards by establishing an electrically safe work condition. To do so, workers must identify and disconnect all possible sources of electrical energy and prevent its reappearance through effective lockout/tagout procedures.
This article of the standard focuses heavily on lockout-tagout principals, equipment, and procedures. It defines the following eight-step procedure for establishing and verifying an electrically safe work condition.
Procedure to Establish an Electrically Safe Work Condition
- Identify and locate all possible sources of electric supply. Check applicable up-to-date drawings, diagrams, and identification tags. 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 stored 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 phase conductor or circuit part 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.
When electrical conductors and circuits over 50 volts cannot be placed into an electrically safe work condition, and work is performed as permitted in accordance with NFPA 70E Section 110.4, the following requirements must be met:
- Only qualified persons are permitted to work on electrical conductors or circuits that have not been placed in an electrically safe work condition.
- A required energized electrical work permit shall be completed.
- Required shock and arc flash risk assessments shall be performed.
When non-routine work must be performed on energized parts or within the restricted approach boundary, a detailed work permit must be prepared before the work can begin. The work permit must document the following elements and be approved/signed by a responsible owner, manager, or safety officer:
- The location and description of the circuit and equipment to be worked on
- 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
- Determination of 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 shall be performed to identify shock hazards, estimate the likelihood and severity of injury or damage, and determine the associated required protective measures, including PPE. 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 determined by consulting tables in the standard based on voltage and conductor type.
Arc Flash Risk Assessment
An arc flash risk assessment shall also be performed by a qualified person to identify arc flash hazards, estimate the likelihood and severity of injury or damage, and to determine if additional protective measures, including PPE, are required. As a part of this assessment, flash protection boundaries must be determined based on the incident energy, and will be the distance at which the incident energy equals 1.2 cal/CM². The distances for common equipment and voltage levels are provided by table in the standard. Others must be determined by specific calculation.
Personal and Other Protective Equipment
Employees working in areas where electrical hazards are present must be qualified to perform the work. They 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.
Section 130.7(C)(15) provides details on selection of appropriate arc rated PPE. Four categories of increasingly protective PPE are defined based on the minimum level of incident energy they provide protection against. The PPE category required can be determined by calculation of the incident energy level or by consulting the table identifying PPE categories for common equipment and voltage levels.
MELTRIC Switch-Rated plugs and receptacles simplify compliance with NFPA 70E by eliminating exposure to live parts and arcing when making and breaking electrical connections to changeout or service motors and other equipment. The hazard is eliminated, so there is no need for cumbersome PPE or time-consuming safety procedures.
MELTRIC Switch-Rated plugs and receptacles are designed specifically to ensure safe use and are UL/CSA rated for branch circuit and motor circuit disconnect switching.
- They have a quick break mechanism that automatically ejects the plug to the ‘Off’ position and minimizes associated arcing.
- Arcing that does occur is safely contained and isolated in internal arc chambers.
- The design of the casings prevents access to live parts when the plug is ejected to the ‘Off’ position; this dead-front is maintained by a safety shutter which closes automatically over the receptacle contacts before the plug can be removed.
At no time in the process is the user subject to potential electrical hazards. Making and breaking connections with them is an NFPA 70E “Normal Operation” and requires no PPE or special precautions.
In addition to eliminating the potential hazards common with pin and sleeve and other types of plugs and receptacles, MELTRIC Switch-Rated plugs and receptacles simplify NFPA 70E compliance by making it easy to establish an electrically safe working condition:
- They provide the safe and proper means of interrupting the load current.
- The removal of the plug from the receptacle provides clear visual verification of deenergization without the voltage testing required on bladed disconnects and rotary switches.
- Integral provisions make lockout/tagout simple on either the plug or the receptacle.
- Work can be done without the need for specially qualified personnel.