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 Post subject: No EWP required within the LAB and the RAB
PostPosted: Fri Oct 03, 2014 8:17 pm 
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Hi all, I have been following the conversations on this great site for a while now but this is my first post. I've tried to be a student of 70E since 2000 and am presently digesting the 2015 addition. I'm going to have lots of questions. Here is what is on my mind now: 130.2 says we have to put the equipment into an electrically safe work condition if a worker is going to cross the LAB. It allows us to cross and do energized work per the exceptions in 130.2A 1 & 2 for greater risk and infeasibility. The 2012 70E would require an EWP at this point if the activity was maintenance or repair. Under the 2015 70E 130.2B1 the EWP is required if I cross the RAB. Am I reading this right? If justifiable under the exceptions of 130.2A 1 & 2 a worker could do maintenance or repair on energized equipment now within the limited approach boundary without authorization, an EWP, as long as he or she did not cross the restricted approach boundary? If so isn't this leaving it up to the worker as to whether the task is justifiable energized? Is this prudent, wouldn't at least an additional opinion from a management type be wise?


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 Post subject: Re: No EWP required within the LAB and the RAB
PostPosted: Tue Oct 07, 2014 8:13 am 
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Let's make it more simple.

The RAB is also known as the "MAD" (minimum approach distance) in OSHA Subchapter R as well as IEEE 516. 70E chose to rename this. I have no idea why. This is the distance at which we would require a QUALIFIED worker to get out the shock protection PPE.

The LAB is the point at which we need to prevent unauthorized access to UNQUALIFIED workers. This is the point where we post barricades. The effect on the qualified worker is nothing.

However, these two boundaries exist only when there is EXPOSED, energized equipment. If it is guarded, isolated, or insulated, nothing is exposed. In most instance it only becomes exposed when you open the door.

There is a second condition. If the work that will be performed interacts with the equipment in such a way that it can create an arcing fault, then a third boundary, the AFB (arc flash boundary) exists. Otherwise, this one doesn't exist either. The UNQUALIFIED workers must also be kept outside this one. So we need to put up barricade tape, post a guard, etc., at whichever boundary is greater.


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 Post subject: Re: No EWP required within the LAB and the RAB
PostPosted: Tue Oct 07, 2014 9:39 am 
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Now with regards to when an EWP is or is not required...

It is required if you are working within the AFB or the RAB. Here's a hint...no exposed conductors and not interacting in such a way that you can create an arcing fault means no EEWP. Otherwise, this is "working on energized equipment" (using the definitions).

In the 2012 edition we can pretty much end here. We are stuck guessing at (or doing a full risk assessment) what "interacting" means. I've seen anything from "anywhere you see an H/RC 0" to "everything except just walking by" as interpretations for that phrase. However the 2015 edition tables give vastly more hints as to what should or should not be considered "interacting". The first of the new tables has several task descriptions followed by a chart of "arc flash hazard?" yes/no. All "no's" mean it's not interacting. If yes, then you go on to the equipment table to determine the incident energy ("PPE level") followed by the clothing table. You could also use the suggested table in the annexes of OSHA 1910.269 which is similar, or develop your own table (doing a risk assessment).

Now with regards to working on energized equipment, there is one final consideration, whether the work is permit required or not. Certain tasks are exempt from a written permit. These are work on equipment under 50 V (no hazard), visual observation (no hazard), and diagnostic work such as startup, troubleshooting, voltage measurement, etc. (can't be done de-energized). The "50 V" rule is treated rather strangely because it gets mentioned in multiple places in every edition of 70E so far, including an extremely contorted definition that requires the end user to determine whether or not there is a shock or arc flash hazard. All I can say to that is that so far there have been no reported cases of a fatality in an OSHA jurisdiction under 50 V, and I can't find any evidence of a significant arc flash hazard at 120 VAC or less (and barely the case for DC). All others require an energized work permit (EWP) or else de-energizing.

The key section of the energized work permit is where justification is provided for doing so and the intention is that this should be a management decision. The justification must be either that a greater hazard is created by working de-enerigzed, or that it is not feasible to do so. Production losses are not an acceptable justification. Note that there is no restriction against "annual" work permits. For instance I strongly recommend considering issuing an EWP annually for 120 VAC. Arc flash is not a concern but shock is. But it is pretty common to insert or remove breakers in lighting panels on the bus and to do a lot of similar things in 120 VAC control systems due to the relatively low risk to anything other than shock. Don't get me wrong...more people die from 120 VAC shocks than other voltages. But it is a huge waste of time and dilutes the purpose of the energized work permit if it is constantly being used for low risk situations. We don't want management conditioned to sign off on 100 permits for changing lighting circuits and then to give a similar cursory glance at fishing new wire into a 480 V, 240 cal/cm^2 live, energized switchgear. And converting MCC's over to under 50 V is an exercise in frustration. It can be done by converting to 48 VAC control voltage but that makes everything special order and nonstandard.


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