Lockout/Tagout Can Save Lives
As safety professionals, we need to always consider the electrical issue as it relates to lockout/tagout.
- By Jeff Buckau
- Aug 02, 2021
In the safety world, one tends to think of lockout/tagout as an electrical problem. People dealing with energized equipment spend significant amounts of time working through the de-energization process to ensure that electricians and quality control people are kept safe from bolts of current flowing through conductors or components. As safety professionals, we need to always consider the electrical issue as it relates to lockout/tagout.
However, there are so many other items to consider when talking about the unexpected release of stored energy in the direction of workers. Some might call it a “line of fire” issue. A lot has been made of the avalanche issue from this past winter season. Snowpack on the side of a mountain has the potential for that unexpected release of stored energy. Millions of tons of snow sliding off the side of a mountain would surely have dramatic impacts on those in the way of the rushing snow slide. However, it isn’t like one could lockout/tagout the side of a mountain, right? Actually, you can. The ski patrol usually does this through proper signage and barricading.
At work, there are many times where stored energy is found near the worker. Gravity, chemical, high pressure, steam, hydraulic, mechanical, etc. are all found on worksites every day. If we were sitting in a classroom, a discussion could be held where examples for each of the items listed above would be explored. Stop for a moment and think of the last time you walked around your worksite and looked specifically for those areas where stored energy might be found.
One such example to discuss would be the case of the mechanic who was working on a cement truck. The truck had a mechanical problem where the mechanic had to climb under the rotating drum to complete the fix. The mechanic placed a “do not operate” sign on the steering wheel of the vehicle, the vehicle was turned off, and the key was removed. However, somehow someone was able to climb into the cab, remove the steering wheel sign and place another key into the ignition, starting the vehicle. As the vehicle started the drum began to rotate and the mechanic was crushed between the rotating drum and the frame, a completely preventable and a totally unnecessary loss of life.
Another area where stored energy could occur on a construction job site would be in an excavation. A hole is dug creating a trench (deeper than it is wide) or excavation (wider than it is deep). The side walls have the potential of stored energy. With the side walls weakened, any slight pressure on the top of the side wall can create a downward sheer force causing the side wall to collapse into the hole. If it’s there by a worker in that area without proper protection, tragedy can occur. We all know that cave-in is the big issue here. The tons of dirt or material caving in around the worker can bury an employee, but it is easily preventable.
What would be the lockout/tagout for this scenario? According to the current standards, there are plenty of safeguards in place for this. The 2,2,4,4,5,6 rule of thumb comes to mind.
- The first 2 is placing spoil piles at least two feet from the edge of the hole. This helps keeps the shear force placed on the non-reinforced side wall of the opening to a minimum.
- The second 2 is that when one is digging below a trench box more than two feet, the trench box must be lowered deeper into the hole.
- 4, if the hole is four feet or greater then oxygen monitoring must be completed to maintain the allowed concentration at 21.5 percent +/- 2 percent.
- Finally, if the hole is more than four feet, the hole needs an egress no greater than 25 feet from the worker.
- If the trench is 50 feet long, how many egress points are needed? When the hole is greater than five feet, the hole side walls need to be either shored, sloped or benched.
- And of course, if the hole is six feet or greater, then fall protection must be used to prevent someone from falling into the hole.
It is a best practice to provide barricades and signage around any opening in the ground to protect not only the worker, but the general public from falling into an unguarded and unprotected area.
One more example of this lock out/tag out system would be around swimming pools. Whether they are commercial or private, they should be fenced and have adequate signage to warn away curious wanderers. In areas where swimming pools are very popular, it is not uncommon for the local news to highlight unnecessary drownings of individuals when these people find their way into an unguarded pool.
Within the world of electricity, the term lockout/tagout is synonymous with making sure there is no stored or residual energy in the circuit. Remember that electricity flows like water in a pipe. It is controlled by the confines of the conductor and its insulation. Should someone become part of that circuit and that person is connected to ground, then the electricity has an opportunity to escape the circuit and go to ground. Which, by the way, is its only real purpose. Perhaps, someday we will be able to communicate with electricity (science fiction, of course) and when we ask what the electrons’ and protons’ purpose in life is, they will undoubtedly say “to go to ground.”
So, when someone makes contact with a circuit and are grounded, guess where the electricity will go? That is correct, to the ground through the person. By de-energizing the circuit and locking it out, the potential of a worker coming in contact with live electricity is minimal. A standard process would be to de-energize the circuit, lock it out/tag it out, dissipate any stored or residual energy and then verify isolation with live-dead-live testing with a voltmeter.
Most electricians know that a voltmeter is a quantity measuring device that measures the amounts of volts, amps and ohms within a circuit. When a system is unplugged or de-energized, there should be zero of all of those. Do not make the mistake of checking live-dead-live with a voltage detector. That is a quality measuring device. Is there energy in the item being tested, yes or no. The professionals in the electrical world call these devices “tic tracers” or “widow makers.”
One other item to keep in mind with lockout/tagout is lock placement and removal. A person is only allowed to remove his/her lockout/tagout device, not anyone else’s. Doing so places the other person in harm’s way. In most companies interfering with someone else’s lock is grounds for immediate termination.
In conclusion, to prevent the unexpected release of stored energy in the direction of the employee, a lockout/tagout device must be placed on systems where the stored energy is found. We all need to be reminded of the very serious and lethal ramifications should we not follow this simple rule.
This article originally appeared in the July/August 2021 issue of Occupational Health & Safety.