Fatalities that are Easily Preventable
I was recently reviewing OSHA accident investigation data from 2020, In one case an employee was pulling wire into an electrical cabinet. At some point, the employee contacted a live wire or other live electrical component in the electrical cabinet. The employee was killed by electrocution. In another report an employee was replacing a photocell in a wall-pack light mounted to the side of a building. The worker contacted an energized wire the shock knocked him off the ladder and he fell to his death after hitting his head on the concrete parking lot. Unfortunately, these stories are all too common.
Why are workers who identify themselves as electrical professionals getting shocked and electrocuted? Aren’t we supposed to know better? The answer to this question could get complicated but the solution to the problem is quite simple. In too many cases electrical workers do not turn off the power putting themselves at increased risk for shock injuries, electrocutions, or burns due to arc flash.
Rules require we deenergize
Many of the citations written by OSHA that relate to electrical accidents include the failure to lock and tag out the equipment. This is because OSHA has strong language that nearly prohibits work on energized circuits. Although general OSHA lockout requirements reside in standard 1910.147 The Control of Hazardous Energy. Electrical work has its own lockout requirements under OSHA. This is because locking, tagging, and trying out is simply not enough to keep electrical workers safe. Electrical workers must go a few steps further including the verification of the absence of voltage and considering the equipment energized until the absence of voltage verification and lock out process is complete. OSHA 1910.333 Selection and use of work practices is where we will find the OSHA requirements for electrical LOTO. NFPA 70E has very similar language in Article 120 Establishing and Electrically Safe Work Condition and Article 110.4 Energized Work.
OSHA 1910.333(a)(1)
“Deenergized parts.” Live parts 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”.
The OSHA standard clearly states that the employees must deenergized before working on electrical equipment unless the employer can demonstrate that certain conditions exist.
Exemptions to the rule
OSHA offers a few exemptions to the 1910.333(a)(1) If deenergizing introduces an additional hazard or increased risk then it is permitted to work on the equipment in an energized state. OSHA gives examples of what they would consider increased or additional hazards these include interruption of life support equipment, deactivation of emergency alarm systems, shutdown of hazardous location ventilation equipment, or removal of illumination for an area.
In most cases emergency alarm systems, life support equipment, and plant lighting are required by other codes and standards to have back-up systems making it, in our opinion, nearly impossible to meet the requirements of this exception.
How Can I Troubleshooting With The Power Off?
Work that may be performed on or near energized circuit parts because of infeasibility due to equipment design or operational limitations include testing of electric circuits that can only be performed with the circuit energized. In some cases, troubleshooting activities must be performed with the power on. You can’t measure voltage or inrush current to a motor with the power off so in these situations OSHA makes an exception to the deenergizing rule.
No Free Pass When Troubleshooting
Keep in mind troubleshooting activities with the power on does not give us a free pass. OSHA 1910.333(a)(2) states “that if the exposed live parts are not deenergized, other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved”.
What OSHA is saying in this paragraph is if you are going to troubleshoot with the power on and you are exposing yourself to a shock and or arc flash hazard, you must employ other safety related work practices including, but not limited to, insulated tools, shields, barriers, and personal protective equipment. Essentially, we have a choice, put on your arc flash gear and rubber insulating gloves or figure out how to troubleshoot with the power off.
Continuous Industrial Process
OSHA makes another exception to the deenergized work standard that is often misinterpreted. After reading the exception production-oriented workers and management members might determine that their production line falls under this “continuous industrial process” exception. Again, this exception is very difficult to achieve. In a letter of interpretation from OSHA dated December 19, 2006. OSHA explains what they consider to be a “continuous industrial process”.
” The term “continuous industrial process” was derived from its use in the National Electrical Code (NEC). In the NEC “continuous industrial process” is used in the context of situations where the orderly shut-down of integrated processes and equipment would introduce additional or increased hazards. Therefore, to qualify for the exception found in Note 2 of §1910.333(a)(1), the employer must, on a case-by-case basis, determine if the orderly shutdown of the related equipment (including the panel) and processes would introduce additional or increased hazards”. Read entire OSHA letter by following the link below.
Energized work less than 50-volts
OSHA 1910.333(a)(1) states that live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
If you have ever accidently placed a wrench from one terminal to the other of a car battery, you know what OSHA is referring to when they say, “no exposure to electrical burns”. Industrial battery banks for UPS systems may fall into this category as well. In some cases, there may be enough electrical power to create an arc flash. However, working on 24-volt control circuits (low levels of electric power) would most likely meet OSHA’s exception. The employer must, on a case-by-case basis, determine level of hazard and determine if protective measure would be required when working in and around the equipment operating at 50-volts or less.
Infeasible Does Not Mean Inconvenient
OSHA states that if de-energizing the conductors or equipment is infeasible due to equipment design or operational limitations energized work is permitted. Keep in mind that there is a significant difference between infeasible and inconvenient, and the two terms should not be used interchangeably. Inconveniences such as “we can’t shut it off because hours of production will be lost” or the worker perceives that it will be much faster and require less effort to work with the power.
How do we stay safe?
There are many factors which effect our decision to work with the equipment energized. This could include pressure to get the equipment restored to a running condition quickly, lack of proper training and qualifications to work on electrical equipment, inaccurate perception of risk, etc. I always tell my students that “the safest way to work on electricity is not to work on electricity”. I go to say that “the rules are written for a reason”. There is a reason that OSHA and NFPA 70E have rules that require us to deenergize. The risk of accidents, many resulting in injury or even a fatality increases dramatically when we work with the power on. Follow the rules that are designed to keep you and your employees safe. Eliminate the risk by deenergizing.
Links to References
OSHA 1910.333 – Use of Safe Work practices
OSHA 1910.147 – Control of Hazardous Energy
NFPA70E 2021 EDITION
OSHA Letter of Interpretation “Continuous industrial processes” and the infeasibility of de-energizing equipment under 29 CFR 1910.333. https://www.osha.gov/laws-regs/standardinterpretations/2006-12-19
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