Common mistakes people make when working on electrical systems

1. Thinking that it’s “only 120 volts”

“It’s only low voltage.” Okay, I’ll admit that you can have an open casket with a low-voltage hit, but you’ll still be dead. The only difference between low and high voltage is how fast it can kill you. High voltage kills instantly; low voltage may take a little longer.

Dr. A.G. Soto, consulting physician to Ontario Power Generation presented a paper at the 2007 IEEE Electrical Safety Workshop discussing low-voltage shock exposures. In that paper, he stated that a 120-volt shock can kill up to 48 hours later. He also stated that many emergency room physicians are unfamiliar with electric shock and that an EKG may not show a problem. The injury to the heart muscle tends to spread over time and cannot always be identified using EKGs.

2. Working on energized systems or equipment when it can be de-energized.

De-energizing is the only way to eliminate hazards. Arc flash personal protective equipment (PPE) just increases your chances of survival; it doesn’t guarantee it. Just be aware that until equipment and systems are placed in an electrically-safe work condition, proper PPE and procedures must be used to protect the worker. See Article 120 in NFPA 70E 2012.

3. Not wearing any PPE.

This could go into number 2 above, but people really don’t like wearing rubber insulating gloves or arc flash PPE and equipment. It’s hot, uncomfortable, restricts movement, and slows the entire work process down — not only by wearing it, but by selecting the correct PPE and putting it on and taking it off.  It will also save your life. One of the most likely times people neglect to wear their PPE is during troubleshooting. The rationale seems to be, “I’m not really working on it; I’m just testing it.”  Yet, CDC/NIOSH studies have found that 24% of electrical accidents are caused by troubleshooting, voltage testing and like activities. We have a tendency to ignore hazards associated with tasks we consider “safe”.

4. Not wearing the right PPE.

Some people think that if they wear anything by way of PPE, that should be enough. Do you know how to interpret arc flash labels? What do you do if there’s no arc flash label on electrical power equipment? Do you know how to use the tables in the NFPA 70E? Do you refer to the notes when you use the tables? If you answer “no” to any of these questions, you aren’t choosing the right PPE.

5. Using outdated or defective test equipment to troubleshoot.

When the leads are frayed or your meter is damaged, it’s time to replace it.  The NFPA committee was concerned enough to put two different requirements for using only portable electric tools and test equipment that were properly rated.

6. Not using an Energized Electrical Work Permit system.

People tend to hate paperwork. This is one great exception. You should plan each job, have the right tools and equipment to do the job safely and follow your work plan. How do you document the Hazard/Risk Analysis or our PPE Assessment? The Energized Electrical Work Permit provides the means to plan the work, assess the hazard and the risk, choose the proper PPE for the job and document it.


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