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Summary of regulations applicable to electrical safety (shock and arc-flash) – in
In Manitoba, the Manitoba Workplace Safety and Health Act (WSHA), Chapter W210 regulates safety in the workplace. Electrical work is covered under chapters 25 and 38.
Article 4(1)(a) of the WSHA, states that « …every employer shall…ensure, so far as reasonably practicable, the safety, health and welfare at work of all his workers… « . In addition, article 4(2)(b) of the Act reads “provide to all his workers such information, instruction, training, supervision and facilities to ensure, so far as is reasonably practicable…”
At the federal level in Canada, it is expected that employers exercise “due diligence”, i.e. do everything that is “reasonably practicable” when protecting their employees against hazards in the workplace. Bill C-45 added Section 217.1 to the Criminal Code which reads:
« 217.1 Every one who undertakes, or has the authority, to direct how another person does work or performs a task is under a legal duty to take reasonable steps to prevent bodily harm to that person, or any other person, arising from that work or task. »
The expected precautions typically include as a minimum complying with the applicable electrical code for all electrical installations. In the majority of Manitoba, the “Manitoba Electrical Code” includes the Canadian Electrical Code (CSA 22.1), with some Manitoba-specific amendments. Note that specific to the city of Winnipeg, the corresponding document “Winnipeg Electrical By-Law” is in effect.
Article 2-306 specifies that equipment that requires servicing or maintenance be field marked with warnings regarding shock and arc flash hazards. This is normally the owner’s responsibility.
The notes regarding Rule 2-306 in Appendix B (which is informative) refer to CSA Z462 for guidance in determining the severity of the electrical hazards.
Z462 Workplace Electrical Safety:
This CSA standard complements the CEC. While the CEC focuses on designing and building safe electrical installations, Z462 addresses the safety of the workers relative to electrical equipment, during installation, maintenance and repairs. It covers work procedures, personal protective equipment (PPE), as well as the training and qualifications of the workers.
Z462 article 4.1.7 clarifies the roles and responsibilities of both the host and contract employers in keeping workers safe.
One of its main recommendations is to avoid live electrical work whenever possible. However, it is also recognized that this is not always possible, for instance when troubleshooting equipment, and even when checking that power has been turned off (during lockout/tagout).
2Z462-15 Annex Q, fig. Q.1 provides an example of a basic label that would comply with the CEC:
While this does alerts workers to some potential dangers, electrical hazards vary widely within industrial settings. Different types of equipment, operating at various voltages, with varying levels of arc-flash hazards are present. The problem with the basic label is that there is no guidance as to what procedures or precautions the workers need to follow. Looking only at this label, it is likely that a court of law would judge that not all “reasonable steps…” were taken to inform and protect the workers.
A more detailed label would look like (fig. Q.3):
Comparatively to the previous editions, Z462-15, which is now in force in Manitoba, has made clearer the requirements that an arc-flash risk assessment is required:
- Article 22.214.171.124 now says “An arc flash risk assessment shall be performed.”
- Article 126.96.36.199.1 does allow two methods for selecting arc-flash PPE:
- Incident energy analysis.
- Selection based on Table 4A, followed by Table 4B (AC current) or Table 4C (DC current), then Table 5.
While it appears simpler to use, the second method is applicable only when some specific constraints are met regarding the available short-circuit current and the fault clearing time (FCT). For instance, some of the categories listed in Table 4B read: “Maximum of 25 kA short-circuit current available; maximum of 0.03 s (2 cycles)fault clearing time; working distance 455 mm (18 in)”. Confirming these assumptions may be difficult, as someone must perform at the very least a short-circuit study and creating time- current curves (TCC)s for each location.
Gathering the information required to perform those tasks usually necessitates a field survey of the installation. It is possible to perform the calculations by hand, but it is time-consuming and error-prone. Electrical analysis software is now available that allows using the same field information to complete the short-circuit study, prepare TCCs and validate the selective coordination, as well as calculate the
incident energy and produce detailed shock and arc-flash warning labels.
Therefore, unless the installation is very small and simple, the second method should probably be used only until a complete analysis is done. That said, using the tables without verifying the assumptions are valid would not be considered acting with “due diligence”.
Note that the analysis needs to be updated at intervals not exceeding 5 years, or whenever major modifications are made to the system, as specified in Z462, article 188.8.131.52.