Managing Electrical Safety
CSA Z462 Workplace electrical safety – Canada’s first national workplace electrical safety standard.
One of the most common questions asked of the technical committee members working to develop CSA-Z462, Canada’s first national workplace electrical safety standard, is: “How’s the arc flash standard going?” While the new standard includes guidelines regarding arc flash and shock it’s far more comprehensive and far-reaching, representing a broad cultural shift in workplace electrical safety.
The cost of an electrical injury or fatality can be devastating, involving tremendous personal cost, particularly following burn injuries. An injured worker may never be able to return to work, treatment can require years of skin grafts and rehabilitation, families are traumatized, and depression and divorce are common. Employers also face such costs as production and equipment downtime, government investigations, legal fees, and workers compensation expenses.
Currently, Canada simply doesn’t have an existing national standard for workplace electrical safety. While various Canadian jurisdictions have developed regulations to address specific electrical hazards, workers continue to suffer serious, even fatal, injuries as a result of shock and arc flash. In 2006, eight workplace fatalities and 18 critical injuries occurred in Ontario alone, reports the Ministry of Labour’s Electrical Incidents and Occurrences Summary.
A voluntary technical committee is developing CSA-Z462, with members selected from stakeholders representing industry, labour and government across Canada.
CSA has scheduled the publication of the first edition of CSA-Z462, which will be known as the Standard on Workplace Electrical Safety, for the end of 2008. Like many CSA standards, it will be presented as a voluntary best practice standard for use anywhere in Canada. Once published in both official languages, the document will be submitted to Standards Council of Canada for approval as a national standard. Each province and the federal government may choose to reference the standard in their own regulations to make it mandatory through such regulatory authorities as the various ministries of labour. The province of Saskatchewan has already indicated an interest in adopting the standard as law. What follows is an advance look at the new standard.
Previous regulations targeted electrical workers only. CSA-Z462 will apply to any workers potentially at risk for working in proximity to electrical equipment, whether they’re HVAC technicians, construction workers, engineers, manufacturing workers, or millwrights. The new standard will also define areas within which anybody—including non-electrical workers and onlookers—must follow strict safety precautions, which include the use of specialized personal protective equipment (PPE).
Many refer to the new standard as the Canadian adoption of NFPA 70E, Standard for Electrical Safety in the Workplace, which was developed by the US National Fire Protection Association (NFPA) and first published in 1979. In the absence of a Canadian standard, many companies have already adopted NFPA 70E, particularly those with operations on both sides of the border.
It’s the NFPA document’s emphasis on arc flash standards that has some Canadians referring to the new CSA standard as “the arc flash standard.” The CSA standard uses the 2009 edition of the NFPA 70E standard as a seed document. Revisions provided by NFPA participants will ensure harmony between the Canadian guidelines and the NFPA’s 2009 edition.
The CSA standard is divided into three main clauses:
- Clause 4 applies generally to safety related work practices Annexes will provide real-life examples for informational purposes, but won’t form part of the requirements of the standard.
- Clause 5 applies to safety related maintenance requirements for electrical equipment and workplace installations
- Clause 6 supplements or modifies Clause 4 with safety requirements for special equipment
KEY ELEMENTS OF CLAUSE 4
Clause 4 describes electrical safety related practices and procedures for workers exposed to electrical hazards in the workplaces covered by the standard (for a list of workplaces not covered, see “CSA Standard Z462 at a Glance”). Since electric circuits and equipment not included might present a hazard to workers not qualified to work near such facilities, Clause 4 includes requirements to protect unqualified persons from these hazards. Information on specific subclauses follows.
Clause 4.1 provides general requirements for electrical safety-related work practices. Clause 4.1 calls for all employers to implement an overall Electrical Safety Program, and cautions that safety-related work practices are just one component. Included are contractor and employer relationships and responsibilities. It also covers training requirements for qualified and unqualified persons.
This sub-clause references CSA-Z1000-06, Occupational Health and Safety Management Standard, which provides a framework for developing and implementing an OHS management system. The clause identifies the importance of establishing an Electrical Safety Program that includes a hazard/risk evaluation procedure to be used before work is started on energized electrical conductors and circuit parts operating at 50 volts or more, or where an electrical hazard exists. CSA-Z462’s Annex E provides an example of a typical Electrical Safety Program procedure, while Annex F provides examples of hazard/risk evaluation procedures.
Clause 4.2 covers the establishment of an Electrically Safe Working Conditions, including isolation, lockout, verification and, if applicable, installation of temporary grounds. In this clause, the principles of lockout execution are taken from a sister standard, CSA-Z460, The Control of Hazardous Energy—Lockout and Other Methods.
One important distinction of this clause is a definition of the term “working on,” in reference to energized electrical conductors or circuit parts. The standard defines “working on” as coming in contact with energized electrical conductors or circuit parts with the hands, feet, or other body parts, with tools, probes, or with test equipment, regardless of the personal protective equipment (PPE) a person is wearing. The standard also clears up a misperception that there is only one category of working on energized equipment, when in fact there are two:
- Diagnostic (testing)—taking readings or measurements of electrical equipment with test equipment that does not require making physical changes to the equipment
- Repair—any physical alteration of electrical equipment, such as making or tightening connections, removing or replacing components, etc.
Clause 4.3 covers justifications for working energized. Under the standard, energized electrical work would be permitted when the employer can demonstrate that de-energizing introduces additional or increased overall hazards; for example, in working on hospital life-support systems that would threaten the lives of patients if shut down. Energized work would also be permitted where the employer can demonstrate that the task to be performed is unfeasible in a de-energized state, due to equipment design or operational limitations.
If electrical conductors or circuit parts are not placed in an Electrically Safe Work Condition, work would be performed following requirements outlined in Clause 4.3 Work involving electrical hazard which may require a written permit to be obtained by the worker. This is known as the Energized Electrical Work Permit.
There is an exemption to the Energized Electrical Work Permit: where work performed by qualified persons relates to tasks such as testing, troubleshooting, voltage measuring, inspection, etc., provided appropriate safe work practices (e.g. use of procedures) and PPE are provided and used. It may be advisable, however, to have a blanket Energized Electrical Work Permit for testing and troubleshooting. The permit could be reviewed at a tailboard meeting on a quarterly or semi-annual basis.
This clause also states that de-energization of circuits is not required for systems of voltage less than 50 volts to ground, such as are found in a 24-volt DC telephone system. Energized work may also be permissible when overcurrent protection is sufficient to determine that there will be no increased exposure to electrical burns or to explosion due to electric arcs.
HAZARDS OF WORKING ENERGIZED
The CSA Z462 Standard addresses two electrical hazards involved with work on energized electrical equipment: electrical shock and arc flash.
Electrical shock is a dangerous condition associated with the possible release of energy caused by contact or approach to exposed energized electrical conductors or circuit parts. Electrical shock can cause serious injury or death.
The Standard calls for a shock hazard analysis, which would determine the voltage to which personnel will be exposed, boundary requirements, and the shock PPE, tools & equipment necessary to minimize the possibility of electric shock to personnel. The shock protection boundaries are identified as Limited, Restricted, and Prohibited. Table 1 in the CSA Z462 Standard identifies the distances required for various voltage levels. The distances are fixed and voltage-dependent, and apply to both qualified and unqualified personnel.
Arc flash with associated arc blast is also a dangerous condition, associated with energized electrical equipment and the possible release of energy caused by an electric arc. An arc flash hazard exists when a person interacts with equipment in a way that could cause an electric arc. Such tasks may include testing or troubleshooting, application of temporary protective grounds, or the racking in or out of power circuit breakers. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard.
To address this hazard, the standard calls for an arc flash hazard analysis— a comprehensive study investigating potential worker exposure to arc flash energy. The purpose of the analysis: to determine the arc flash protection boundary, and appropriate levels of arc flash protective PPE.
The standard does not require an arc flash hazard analysis where all of the following conditions exist:
a) the circuit is rated 240 volts or less
b) the circuit is supplied by one transformer
c) the transformer supplying the circuit is rated less than 125KVA
DETERMINING AN ARC FLASH PROTECTION BOUNDARY
Clause 4.3 also provides direction on determining the arc flash protection boundary for voltage levels between 50 and 600 volts. At this boundary, an arc flash event would create enough heat incident energy (e.g. heat released from an arc flash) to cause a curable second degree burn to the bare skin of a worker.
Where it has been determined that work will be performed within the arc flash protection boundary, two methods are offered for the selection of protective clothing and other personal protective equipment (see “Determining an Arc Flash Protection Boundary”).
As well, Clause 4.3 details other areas, such as:
- care of personal and other protective equipment
- test intervals for rubber insulating equipment
- protective equipment standards
- factors in selecting protective clothing and equipment, clothing material characteristics, care and maintenance of flame-resistant clothing, arc flash suits and insulated tools and equipment
CLAUSE 5: REGULARLY SCHEDULED MAINTENANCE
Clause 5 covers practical, safety-related maintenance requirements for electrical equipment and installations that are directly associated with worker safety. First, some maintenance-related statistics:
- studies by the Electrical Safety Authority of Ontario indicate that 60% of safety incidents can be attributed to maintenance activities
- a 2007 survey performed by the International Electrical Testing Association (NETA) indicates that 22% of serviceaged circuit breakers had some type of malfunction, and 10.5% did not operate at all during maintenance testing.
Improper equipment operation can drastically increase the risk of worker exposure to electrical hazards
There are two main North American industry standards for maintenance of electrical power distribution equipment systems:
- NFPA 70B, Recommended Practice for Electrical Equipment Maintenance
- NETA Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems
These standards are used in conjunction with manufacturers’ individual recommendations to provide an overall Electrical Equipment Maintenance Program.
CLAUSE 6: SPECIAL ELECTRICAL EQUIPMENT
This clause, which supplements and modifies the general requirements of Clause 4, is divided into six sections, covering
- general requirements
- electrolytic cells
- batteries and battery rooms
- power electronic equipment
- safety-related work requirements for research and development laboratories
Once CSA-Z462 is published, it will offer workers and companies far more than arc flash awareness and injury prevention. Such items as lockout, preventive maintenance of electrical equipment, personal protective equipment, and safety-related work practices and procedures are all key components of a workplace Electrical Safety Program and covered in the new standard.
The CSA-Z462 Technical Committee strongly recommends that companies adopt the standard proactively. It represents a major change in the way that workplace electrical work will be conducted in Canada, and will serve as an important tool for preventing workplace electrical incidents.