Page 18 - Occupational Health & Safety - eDITION, August 2017

SHOCK RISK ASSESSMENT
DITION
Shock Risk Assessment in the Workplace
Depending on how you break it down, there are about seven steps in Z462-15 for completing a good shock risk assessment.
TBY MIKE DOHERTY
he source of risk assessment procedure best practices that you find in CSA Z462-15 “Workplace electrical safety” (Clause 4.1.5.7) is CAN/CSA-Z1002-12 “Occupational health and safety - Hazard identification and elimination
and risk assessment and control.”
Z1002’s technical committee has done an outstanding job
of compiling a common language for defining leading-edge job planning techniques. The resulting generic risk assessment pro- cedure can be used for any hazard in any workplace, as the com- mon language and well thought-out methodology are useful on any job site.
In the electrical workplace, a comprehensive electrical risk as- sessment procedure must be completed by safety-qualified person- nel; that is, someone qualified to CSA Z462-15 “Qualified persons.” Specifically, look at Clause 4.1.6.4.1 (b)(iv), (1), (2), (3) and (4).
You may be a licensed electrician or professional electrical engineer, but that does not necessarily mean you are a qualified person when it comes to electrical safety. It is critical to ascertain whether your licensed electricians and electrical engineers are truly safety-qualified in alignment with Clause 4.1.6.4.1, as well as those you contract.
Only when due diligence requirements are met—and you’ve ensured safety-qualified personnel are truly in place—can compre- hensive and effective electrical job planning begin.
Using the principles of the generic risk assessment procedure, the path for any electrical work splits into two sections; I always start with a comprehensive shock risk assessment. While a compre- hensive arc flash risk assessment should also be completed as re- quired), the rest of this column will deal primarily with the former.
To execute a thorough shock or arc flash risk assessment, you need to be able to navigate CSA Z462, which, admittedly, is not laid out so as to provide a simple procedural walkthrough. No, you need to take time to make your way through the standard to ensure you have all the details, then document them in your own written electrical work procedures.
You cannot expect your supervisors and workers to use Z462 to execute efficient work without first transferring its risk assessment
When they know the work at hand, a competent and qualified electrical person can usually quite easily determine the voltage(s) to which personnel could be exposed.
procedures to a logical flow for an electrical workplace. Depending on how you break it down, there are about seven steps in Z462-15 for completing a good shock risk assessment. Specific details are in the standard but, on page 35, you will find Clause 4.3.4.1 “Shock risk assessment,” for which there are three
basic determinations:
1. Voltage to which personnel will be exposed.
2. Boundary requirements.
3. PPE necessary to minimize the possibility of electric shock. When they know the work at hand, a competent and qualified
electrical person can usually quite easily determine the voltage(s) to which personnel could be exposed.
As for the second point, there are two boundary requirements in Z462-15 (the 3rd boundary requirement—Prohibited—was re- moved from the 2015 version). Clause 4.3.4.3 gives specific details for the Limited Approach Boundary, which applies to approach by unqualified persons, working at or close to the Limited Approach Boundary, and entering the Limited Approach Boundary.
Requirements for the second boundary—Restricted Ap- proach—can be found in Clause 4.3.4.4, which also provides guid- ance for qualified and unqualified personnel. Tables 1A and 1B on pages 36 and 37 give the particulars for AC and DC equipment, which are, in fact, distances calculated from specific voltages.
The PPE requirements for the identified shock hazard can be found on page 130, Table H.3 “Summary of specific sections de- scribing PPE for electrical hazards.” Your next source of guidance is found on page 42, Clause 4.3.7.3.7(a) “Shock protection.”
For the sake of due diligence, after you’ve transposed Z462’s shock risk assessment requirements into a simple, effective, busi- ness-specific electrical procedure, have your efforts signed and dated by the accountable management team.
Mike Doherty is the president and owner of Blue Arc Electrical Safety Technologies Inc. since 2003 and an independent consultant and trainer for e-Hazard in Canada. He is a licensed electrician, Industrial Instrumentation Technician, Engineering Technician and H&S professional, serves as the Technical Committee Chair of CSA Z462—Workplace Electrical Safety, since inception in 2006, and the official liaison between Canada (CSA) and U.S.A. (NFPA) for elec- trical safety from 2006 -2015 & 2017 to present. He was the H & S manager and consultant at PowerTel Utilities Contractors Limited, a high voltage specialist in transmission, distribution, and substation construction and maintenance and currently is the IEEE IAS Elec- trical Safety Committee—Construction Subcommittee chair. This article first appeared in Electrical Business Magazine, March 2017, www.ebmag.com
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