Did you ever stop to think of the vast number of switches and circuit breakers found in the world? They are found in virtually every market and application around the globe. Operation of those circuit breakers and switches is a common task. It is probably very conservative to say that they are being operated tens of thousands of times each day. Even so, prior to moving the handle workers should always assess the risk and confirm that the equipment is in normal operating condition.
Normal Operating Condition
Clearly the likelihood of arc flash incident is high when employees are working on or near exposed live parts. Live parts are considered to be exposed when they are not suitably guarded, isolated, or insulated. Normal operation of enclosed equipment is not likely to result in an arc flash provided it is in a normal operating condition. So how do we define normal operating condition? A great start is found in the Standard for Electrical Safety in the Workplace, NFPA 70E. Here you will find that to be in normal operating condition, the equipment must:
- be properly installed.
- be properly maintained.
- used in accordance with instructions included in the listing and labeling and in accordance with manufacturer’s instructions.
- have doors closed and secured.
- have covers in place and secured.
- not show evidence of impending failure.
To consider the equipment in a normal operating condition all six of these conditions must be met. If any of the criteria are not met, the equipment is not in a normal operating condition and additional protective measures, including the use of PPE, must be considered.
Understanding the Conditions
Reviewing each of these criteria will help us to better understand them.
The phrase “properly installed” means that the equipment has been installed per the manufacturer’s instructions and installation codes and standards. Consider the wiring methods, workmanship, clearances, operating environment and commissioning.
The phrase “properly maintained” indicates that the equipment has been maintained in accordance with the manufacturer’s recommendations and industry codes and standards. These are published by organizations such as NEMA and NFPA. A comprehensive maintenance program is invaluable and real time asset monitoring methods can help users gather even more information related to the condition of maintenance.
The next criteria are that the equipment is to be used in accordance with the instructions and the listing and labeling. These criteria address potential misuse or misapplication of the product and ensure it is used per the product standards.
The following two items point out that equipment doors and covers must be in place, closed and secured. These are self-explanatory since open or missing equipment covers can expose live parts and increase the likelihood of creating both shock and arc flash hazards.
Finally, the phrase “evidence of impending failure” encompasses a variety of issues. These include arcing, overheating, loose parts, bound mechanisms, physical damage, water or dust contamination, certain odors and corrosion. Workers can use multiple sensory inputs (hearing, seeing, touching, and smelling) to identify signs of impending failure.
Repetitive tasks can cause complacency and overconfidence. Prior to operation, workers must make a habit of confirming that equipment is in normal operating condition and know what to do if it is not. Stay up to date on NFPA 70E by joining our Electrical Contractor Portal.
4 years ago
Thank you for the information. will be sharing on my blog.
4 years ago
Nice post. Thanks for sharing such type of valuable article. Keep sharing this type of informative post.