top of page

The Importance of an Effective Verification Step in Lock Out Tag Out

Engineer checking electrical equipment

Controlling hazardous energy, better known as lock out tag out, is an essential safety measure for anyone working on electrical or mechanical equipment. It is a critical procedure that needs to be performed with utmost care and attention to detail. The main objective of lock out tag out is to ensure that equipment is de-energized (i.e. the equipment can't start up on you) so that workers are safe from any potential harm before performing maintenance or repairs. One crucial aspect of lock out tag out, which is sometimes overlooked, is the effectiveness of the verification step. You don't really know something worked if you don't test it, do you? In this post, we'll cover why the verification step is critical and how to make sure it's effective.

Verification Keeps Dangerous Equipment From Hurting You

The grim reality is that hazardous energy, when not controlled, can lead to severe, even fatal injuries. This unsettling proposition is not limited to those working in industrial settings but extends to anyone interacting with mechanical or electrical equipment, be it commercial, industrial, or even household level. Despite the meticulous planning and execution of procedures to de-energize equipment, there remains a lingering uncertainty: Has it truly worked? Enter the seemingly simple, but vitally important, step of verification. Verification serves as the ultimate test of a successful lock out tag out procedure. It is the fail-safe measure that ensures the hazardous energy has been thoroughly isolated from the equipment, thereby guaranteeing its safe state before any work commences. Without this crucial step, the effectiveness of the entire lock out tag out process remains in question.

Verification Methods and Considerations

Testing new equipment

That said, there are good ways to verify and there are not so good ways. One thing some companies may do, and I can see why, is to make use of electrical main disconnects. These disconnects usually have many electrical and mechanical equipment connected to them. So, it seems to be a logical choice in achieving a safe energy state for the downstream equipment to be worked on. The rationale behind this approach is that by flipping a single switch, all downstream equipment linked to the disconnect can be de-energized, creating what appears to be a quick, efficient lock out tag out solution.

The Perceived Benefits and Potential Pitfalls of Using Electrical Main Disconnects

Shutting off and locking out a main disconnect does indeed seem like an easy and effective solution. Properly wired, installed, and maintained, this approach will indeed cut power to everything downstream of it, including any machine controls. However, this method has its pitfalls. It operates on the assumption that the disconnect will work flawlessly all the time, which is not always the case. Normal wear and tear or unforeseen damage can lead to a failure, creating a potentially dangerous situation. Moreover, this approach often results in the elimination of control power for the machine controls. Consequently, they can't be utilized as part of a verification step. This is problematic because although you're aware that the control power is cut, such as the control lights going out, there's no certainty that the source power - the power that ultimately drives the machine - is also cut. This disconnect between the control power and the source power can prove to be a hazardous oversight in the lock out tag out process.

In addition to the mentioned methods, there are also lock out tag out devices that can be installed or are built into some models of electrical disconnects to serve as verification indicators. These verification indicators typically feature lights that illuminate when the outbound energy side of the disconnect is active. When you turn the disconnect switch to the off position, these lights extinguish. These indicators are specifically designed for this purpose and can be extremely useful for those who wish to employ electrical main disconnects for a simplified lock out tag out process. Incorporating these devices into your lock out tag out procedures can offer an added level of security, providing a clear, visual confirmation of the energy status and significantly enhancing the safety measures in place.

Using Equipment Controls

A simpler, more feasible method to ensure your verification step is effective involves maintaining power to the controls and using them to attempt to start the machine. By doing this, you are essentially simulating a failure scenario. Depending on the specifics of your equipment, you may even hear the controls or associated parts trying to engage and start the machine. However, if you have successfully disconnected the true energy sources that power the machine, not just the controls, then the machine will not start. It physically can't! This is the exact outcome that your lock out tag out procedures should produce. Ensuring that your machine cannot start even when the controls are engaged provides a tangible, effective verification of your lock out tag out procedures, substantially reducing the risk of unexpected startup or release of stored energy. It's an extra layer of assurance that truly takes the safety of your workers to the next level.

Dealing With Residual Energy

Observing and ensuring that all residual energy sources have been released or bled off is a critical component of the lock out tag out verification process. This can be achieved in various ways depending on the type of equipment you're dealing with. For instance, on certain machines, you might need to open specific valves to allow hydraulic fluid to flow back into the pump reservoir. In some cases, you may need to utilize the controls themselves to bleed off any remaining air or hydraulic pressure. However, one aspect that may be overlooked, yet is incredibly vital, is the observation of movement in machinery. Namely, you want to observe that moving machinery has come to a complete stop. For example, a machine component with significant mass that rotates at high speed can continue spinning for some time even after its energy sources have been shut off. A large wood chipper is a good example of this if it wasn't installed with some good magnetic stops. If someone attempts to work on such moving equipment, it could lead to dangerous, even catastrophic, outcomes. Therefore, to truly ensure the safety of your workers, your verification steps should always include observing that all moving equipment has come to a complete stop before any maintenance or repair work is initiated.

Electrical Lock Out Tag Out

Electrical control center

In situations where work needs to be performed on electrical equipment, such as replacing an electric motor or installing a new electrical disconnect, the process for verifying a de-energized state slightly differs. One potential hazard is electrical arcing, which can occur simply by opening an electrical panel that isn't internally covered. Also, there are electrical shock hazards. Proper training and the use of adequate personal protective equipment typically mitigate these risks. To work on any electrical equipment, you must go upstream to what powers it and verify that the equipment you're working on is de-energized using electrical testing equipment. Only after this verification, and once the energy sources are locked out, can you proceed. This process allows for the safe removal of personal protective equipment and the commencement of the work.

When undertaking electrical work, significant considerations need to be taken into account. One major component is adhering to the requirements set forth by the Occupational Safety and Health Administration's (OSHA) electrical standards. These standards provide a comprehensive list of requirements (for construction and general industries) aimed at ensuring the safety of workers interacting with electrical systems. The standards encompass a variety of areas including, but not limited to, design safety standards, safety-related work practices, and safety-related maintenance requirements. By adhering to these requirements, you can ensure that any work conducted on electrical systems is carried out in the safest manner possible, mitigating risks associated with electrical arcing and shocks. Be sure to familiarize yourself with OSHA's electrical standard to fully understand all necessary safety precautions before embarking on any electrical work.


In conclusion, the verification step in the lock out tag out procedure is arguably the most crucial. It's the point at which your safety procedures are put to the ultimate test. If your procedure fails at this step, it's essential to halt all work until you can verify with certainty that the equipment won't unexpectedly start or that no hazardous energy can reach you. Anything less is akin to gambling with your well-being -- a risk that no one should take. Workers dealing with potentially dangerous equipment have their very lives at stake. Having seen the ferocity with which machinery can manipulate raw materials like rocks, metal, or wood, it's a sobering reminder of what could happen if safety procedures are not rigorously adhered to. Employing lock out tag out procedures isn't just about meeting OSHA's standards -- it's about ensuring you can safely return home at the end of the day.

31 views0 comments
bottom of page