Analysis of electric shock which could have been avoided

According to Tucker and Keefe (2019) of the University of Regina, the annual percentage of non-fatal accidents in Quebec between 2010 and 2017 remained relatively constant (slightly less than 2%). The rate of fatal accidents fell slightly during the same period, from 2.6 to 1.6 (per 100 000). For example, with regard to accidents related to electricity, in 2018 this represented 164 cases and 161 in 2017, a little more than 2 per day on average (CNESST, 2019).

Below is the description of a fatal electrical accident happened during the last year in a new home built. The victim had to clean the apartment for delivery and was electrocuted by coming into contact simultaneously with the dishwasher and the stove in the kitchen.

For the purposes of the investigation, an electrical continuity test has shown that there is earth continuity between the cooker chassis and the earth continuity rod of the plug. The continuity of the stove masses was not faulty either.

Finally, specialists realized that the grounding conductor and the live conductor were reversed in the wall outlet. The 120 V difference between the dishwasher and the stove chassis caused an electrical current of 100 mA to pass through the worker’s body, causing electric shock.

Various factors influence the severity of injuries caused by an electric shock that passes through the human body. Among these factors are the path taken by the current in the body, the potential difference, the intensity of the current and the resistance of the human body. But on average, from 25 mA the current is high enough to cause serious injuries and from 80 mA the risk of death is very likely.

The investigation showed that the company that did the electrical work does not keep any documentation of the verifications done on the connections. A simple check of the operation of the wall outlet would have immediately helped to detect the error and correct the problem. This is, moreover, a requirement of the Canadian Electrical Code.

To minimize the probability of accidents, it would be important to develop an electrical safety program in all companies and to know what to do in the event of an electric shock.

To learn more about the electrical safety program (PSE) you can read our blog. You can also consult our blog on the notion of competence and electricity to know what tasks will have to be performed by a trained electrician.

You can also follow our online training on PPE against arcs and electric shocks and qualifications and electrical safety.

References

Regulation respecting occupational health and safety in Quebec, c. S-2.1, r. 13. (RSST)

CNESST, (2019). Annual statistics 2018. DC200-1016web.

Online: https://www.cnesst.gouv.qc.ca/Publications/200/Documents/DC200-1046web.pdf

Tucker, S., Keefe, A. (2019). 2019 Report on Work Fatality and Injury Rates in Canada. University of Regina.

CNESST, (2019). Fatal accident that occurred on May 28, 2019, at a worker at 9070-3422 Québec Inc .. CNESST, Investigation report EN004205.

Online: https://www.centredoc.cnesst.gouv.qc.ca/pdf/Enquete/ed004205.pdf