It is surprising that users of a consensus standard think that by applying the requirements they are always following best practices. Although standards are a starting point they are more often than not only a starting point. In other words, the requirements of a standard or code are at a level that the public or industry came to a consensus on. Some wanted it to do more and some wanted it to do less. Of course, there is a practical limit to a return on the investment. You could spend billions of dollars to achieve a negligible increase in electrical safety. That is also a factor when it comes to a best practice. In any event, I am not aware of any available standard which requires the absolute most that can be done. NFPA 70E® is no exception since it is a consensus standard.
If NFPA 70E®, Standard for Electrical Safety in the Workplace® were the “best practice” it would only need to contain one requirement. That requirement would simply state ENERGIZED ELECTRICAL WORK SHALL NOT BE PERMITTED. That would be it. End of standard. Use an on/off switch. An inexpensive way to achieve an extremely high level of electrical safety. If there is no electricity then there should be no electrical hazard. That would be the best available practice (FACT: it is the primary method of protecting an employee required by both NFPA 70E and federal regulations). Doing anything other than this would not be the best practice since it would only serve to increase the risk of injury to the employee. Everyone should agree that something that greatly increases the potential for a negative outcome should not be considered to be the best practice.
We all know that it is not an option to have this one requirement. So, the consensus standard provides a compromise of what can be done if the best practice is not applied. Again, these compromises are not the limit of what can be done and should not be considered as such. The requirements serve to establish an accepted consensus level of safety. I cannot think of any code or standard that prohibits you from doing more than what is required. There are many things that could be used to illustrate this point but I will pick one. Think about what you do when you have justified energized electrical work, have exhausted the hierarchy of risk controls and are at the step of specifying arc-flash PPE. Do you use the minimum of the standard or do you go beyond it?
You have done an incident energy analysis and have determined through calculation that the incident energy will be 11.8 cal/cm2 at a working distance of 18 inches. If available do you permit the use of gear rated 11.8 cal/cm2? Do you round it up to 12 cal/cm2. The standard would allow either. Do you try to rationalize that the calculated energy should be a higher value than the real world arc-flash were one to occur? Do you keep it at less than 12 cal/cm2 because an arc-flash hood is necessary if it were greater? Do you specify something else? Maybe something rated even higher? Think about your answer before continuing on.
Thought about what you would do? Now consider how you arrived at this point. You applied risk controls which included administrative and behavioral controls. You selected one calculation method which used the expected parameters and relied upon the function of several pieces of electrical equipment. This provided you with an anticipated incident energy at a very specific working distance. You will specify arc-flash PPE which has a 50% chance of the wearer receiving a 2nd degree burn based on testing of samples at a specific incident energy. Is it a “best practice” to use 11.8 cal/cm2 rated PPE for a calculated incident energy of 11.8 cal/cm2? Would the answer be the same if you were the one wearing the gear to perform the energized work?
Standards are written through a consensus process involving all types of interests, industries and the public. Some of these entities will have needs which exceed the requirements of a general standard. Standards and codes have to provide some guidance but only you can decide if the requirements are your “best practice.”
Next time: The burden of increasing the likelihood that you return home each day.