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This was pretty common prior to around 2008 when 70E itself was written in such a way that the limited approach boundary "triggered" arc flash requirements. So the assumption in many plants by the way it was worded was that doors closed = no hazard. This interpretation temporarily disappeared around for about 6 or 7 years and has now reappeared in a way in the current (2015) edition, although it still existed although implied in the definitions during the entire time.
Fundamentally, electrical equipment is very reliable as long as it is designed, installed, and maintained properly. While we have an extensive definition of the first two conditions embodied in the National Electric Code and NESC, no such animal exists in total in terms of maintenance. So although it is clearly recognized as a requirement, there is not much in the way of a concrete definition of what "proper maintenance" means.
It is so reliable that it is frequently more likely to be killed in a plane crash than by electrical equipment while just "walking by". So on a comparative basis just as planes are not required to carry parachutes for every passenger, 5 point safety harnesses, ejection seats, etc., electrical equipment does not need any special treatment for just walking by or being in the room with it. It is only when we begin interacting with equipment that things get more interesting.
And on that note again, equipment that is properly designed, installed, and maintained, doesn't generally "blow up" even while normal operation such as operating disconnects or circuit breakers, displays, etc., are occurring. Similarly certain types of maintenance such as infrared inspections in and of themselves are no worse than "just walking by". There are some activities that are clearly outright dangerous though such as inserting or removing jumpers on energized terminals, although it can and is done safely on a regular basis by utilities across the country. Many electrical personnel though have been severely injured when equipment is unknowingly energized, or when tools, parts, or materials accidentally drop into energized equipment. A smaller percentage of personnel have been injured while working on equipment following a fault due to a hidden failure.
In all of these cases, the general approach is to minimize this type of work to that which is absolutely necessary (hence the requirement for an "EEWP"), and if it must be done, use a hierarchy of controls with the last line of defense being PPE to minimize either the likelihood or the magnitude of the potential hazard.
In reference to your specific case of operating breakers then, this is where there is some divergence of opinion. Breakers are rated for a limited number of electrical trips and the lifespan gets exponentially shorter as the fault current increases. Barring some recent monitoring equipment for switchgear, there is generally no way to tell if the last fault was the last time that the breaker was rated to successfully open. As a result standards such as NEMA AB4 require an inspection of the breaker following a fault. If this is not done, operating the breaker has a pretty good potential for ending badly. In just the last 6 months, I've run into this on 4 different breakers (older ones).
There is also a major flaw in 70E. The tables in 70E require the doors closed. This is a huge mistake. The issue is whether or not the employee is within the restricted approach boundary. This creates a lot of aggravation and hand waving when it comes to equipment which is protected by location rather than by enclosures such as overhead switchgear. OSHA 1910.269 Annex gets this right. Kudos to them.
The fundamental issue here is that we are dealing with 4 different conditions. First condition on whether or not PPE is required depends on the equipment. For example low voltage or severely curent limited equipment that can't generate much of an arc is or should be exempt. Similarly, when employees are out of harms way or not doing any activities which can cause an arc flash in the first place, it should be exempt. When either or both of these situations coincide though, arc flash mitigation (again, PPE is only one option and not the best one) should be done.
So...the choices are:
1. Require PPE every time. This is knee jerk, ridiculous, and pretty much how 70E has been written from around 2009 until the 2015 edition, and the 2015 edition is still not clear on this point.
2. No PPE ever for operating breakers. 'No need to comment on how stupid this is.
3. No PPE required if the doors are closed. Again, this is how Article 130 was written and interpreted not too long ago. It's wrong but gets closer to the correct answer.
4. No PPE required unless the equipment fails to meet the properly designed/installed/maintained criteria or there is some obvious indication of defective equipment, or the employee is doing something that requires crossing the limited approach boundary or is doing an activity that may cause a problem regardless such as working directly over the top of energized equipment with tools or materials that could potentially drop into the energized equipemnt. Again, this is a simple list of conditions of concern. The task list in 70E-2015 is huge and has a lot of issues with the way that it is written.
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