I work in a chemical facility and was recently informed that in order for production technicians to operate 480V breakers with the covers secured this would require 25cal arc flash PPE. I have not been able to confirm this level of PPE requirement.
not into electrical
This is 2008:
Wow talk about a sensitive topic. Let me give you my opinion, and as I do I’ll try to break down what I know for you.
The Standard for Electrical Safety in the Workplace (NFPA 70E, and here I am talking about language that is fairly consistent over the last thee releases of the standard, 2009, 2012, and 2015) recognizes that there is a Risk (with associated potential hazards) with the operation of electrical devices (circuit breakers and switches are the ones when tend to think of first). When electrical equipment is interacted with (operated, in this case) there is always a chance that it might fail to perform as designed and expected. When electrical equipment does not perform as designed, the failure modes can vary from slight and unobservable, to catastrophic, and anyone who has worked in the trade long enough has probably seen both.
However, effort is made to recognize that manufacturers test their equipment, rigorously, to ensure that if (IF, BIG IF) that equipment was installed and maintained properly, and is not being used in a system that exceeds its ratings, its failure, even if catastrophic, should be contained by the enclosure it is part of, in accordance with the listing provided.
And this is where out in the real world things get complicated. We acknowledge (those of us who work in the construction and maintenance industries) that not all electrical equipment is:
Used in accordance with the listings it is provided with
And this makes determining just how much risk there actually is, with operating these devices, when energized, in the field, difficult at best.
The Standard has a statement, identifying these conditions, which suggests that operating devices in “normal” configuration does not introduce a hazard of the sort requiring specific mitigation (electrical safe work practices, including the wearing of PPE).
If it is your responsibility to ensure that every effort is made to protect workers from hazards associated with working on or near energized electrical devices, OR you yourself are employed working on or near energized electrical devices, ask yourself, “How confident am I that this equipment meets those criteria? Is it installed correctly? Has it been maintained (in accordance with manufacturer’s instructions at least) correctly? Is it listed by the manufacturer for short circuits that it might be expected to withstand?”
If the answer is even a little bit “I’m not sure,” then why wouldn’t you take the precaution of wearing the proper PPE?
If, on the other hand, you can be sure your facility is making every effort to put electrical safety at the top of your priority list, and those criteria are met, and well documented, you should be confident in allowing employees to operate devices without PPE, but then again, who is taking the risk?
The issue, operating electrical devices in normal configuration, is a widely debated and discussed topic, and I image my answer wasn’t all that helpful. But let me address the other part of your question
The specific level of PPE required (by the individual or organization calling out 25 cal rated PPE) SHOULD be based upon one of two things, either a specific calculation (done by a qualified engineer, or perhaps on software programs designed to produce those kinds of results) or from an understanding of the application of the tables found in part 130.7 of NFPA 70E (and I could write a whole new response on that topic *sheesh*), but in either case, the level of PPE should be derived from the potential hazard associated with the equipment. Some companies might think it is easy to default to a “category” of PPE thinking the higher the better, but many working people will tell you that this is not always the case.
Good luck, and if this answer just gave you more questions, I’ll be happy to work through them with you.
Take a look at NFPA 70E Table 130.7 (NFPA 70E: Standard for Electrical Safety in the Workplace® ). It shows that operation of a circuit breaker with the doors closed (normal operation) is a category 0 risk - regular (non melting - cotton) shirt/pants.
If the panels are in place (normal operation) there is NO SPECIAL CLOTHING requirement except non-melting fabric/natural fiber - also in table 130.7
Switchgear is another story
Just to be clear, Normal Operation implies
Listed for the available fault current.
Since I am out at the plant at 2:00 am waiting to verify a process repair I will also add my thoughts. Actually, David and Rick both did a very good job but hey, here I am.
I notice that you joined the Xchange and posted your question immediately which I think is fantastic, it shows that you are willing to reach out for for solutions to issues that are concerning to you.
My proposal is such,
(1) Identify (make a list) of all the possible hazards involved. Involve other team members in this effort. If your electrical equipment meets all of the parameters requirements to enable using the charts provided in the 70E, use them. If not conduct an study to verify system configuration, determine hazard levels and approach boundaries. Keep in mind that the hazard, unless eliminated by disconnecting power from the equipment, remains. Securing the doors does not remove the hazard. PPE does not remove the hazard.
(2) Assess the risk(s). List the individuals or job classifications that will be interacting with the equipment and what tasks they will be required to performed. What will each persons exposure to the hazard be? Examine how often, how many, and how long they will be exposed. Determine the condition of the equipment and maintenance intervals. Have the individuals been trained to perform the task that they will be required to perform as part of their normal duties? The result of a good risk assessment, after taking into account all available information, will provide the likelihood of an occurrence for a person performing a certain task on a particular piece of equipment.
(3) So...Let's say you have a motor control center that has a determined incident energy of 25 cal/cm2. The electrical equipment was installed using the most up to date standards available at the time. Company records show that maintenance has been kept up and the equipment is in good repair. There is no evidence of an impending failure.( no funny smells, unusual noises, abnormal conditions) All the covers and doors are in place and secured. Employee "A" has been trained in the proper operation of the equipment and is operating the equipment as the manufacture intended it to be operated. The likelihood of an occurrence in which employee "A" would be injured is considered to be minimal. The language of the 70E 130.2(A)(4) "Normal Operation" recognizes this as does Table 130.7(C)(15)(A)(a). But...your company must identify each hazard and evaluate the risk for each worker.
Stephen Benton, CESCP
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