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 Post subject: Significance of an Equipment Labels PPE Requirements
PostPosted: Sat Feb 10, 2018 9:04 am 
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Joined: Fri Oct 03, 2014 7:11 pm
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Location: Illinois
Hi All,
What is the significance of a labels listed arc flash PPE requirements? If my arc flash risk assessment indicates the likelihood of an arc event than I have the information available to dress accordingly. If my arc flash risk analysis indicates an arc event is highly unlikely than would it be considered appropriate to work within the arc flash boundary without arc rated PPE? If my understanding of this is correct than my next question is about arc flash PPE requirements for diagnostics/troubleshooting versus repair/maintenance. The job planning requirements including the arc flash risk assessment would indicate the level of PPE required regardless of the equipment's label requirements for PPE? If the technician is troubleshooting why the conveyor stopped is it 70Es expectation that a Job Plan has been first created and documented including the arc flash risk assessment? Even if this is 70Es expectation I'm thinking it is probably not happening much. In this case the technician would follow the equipment's label PPE requirements?
Any thoughts about what I might have right or wrong in regards to this would be much appreciated.
Thanks,
Jerry


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 Post subject: Re: Significance of an Equipment Labels PPE Requirements
PostPosted: Sat Feb 10, 2018 10:52 pm 
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First I'm not entirely sure where you are going with this. The risk depends not only on the condition and sometimes the type of the equipment but the task. Take for instance a draw out "ANSI" style breaker with a separate controls cabinet that houses the protection relay. I think we can both agree that no PPE is needed to operate the breaker with the trip/close buttons nor to check readings and settings at the relay. That's because clearly there is no shock hazard because nothing is exposed. Arc flash PPE MIGHT be necessary if the breaker is in bad or questionable shape in the first place but then again if it is and the activity is anything other than maintenance to get it into that condition, 70E makes it pretty clear that the arc flash study is worthless in the first place if you're not going to maintain your equipment. So this should be the exception rather than the rule when it comes to operating the breaker.

There might be some additional requirements if we open the door of the control compartment to do some kind of work. At this point the arc flash hazard is almost always nonexistent because there just isn't anything in there that exceeds 120 VAC and so arcing faults can't sustain an arc with the one single exception of breaking a lead on the CT leads. Although there are some theoretical arguments making a case for a hazard here they are pretty weak overall and the fact is that the CT itself or the CT wiring tends to vaporize so fast that the arc flash calculation doesn't really capture the reality. Still most older breakers tend to have some very "open" wiring in them. When I'm working on one generally its very easy to avoid contact but there are sometimes some very tight situations where it's hard to reach over or into some spots for testing, particularly when large components are sitting in the middle of the floor of the cabinet and you have to reach over them to get to something else. That's when the gloves come out.

There really isn't any danger either to simply open the door on the breaker itself because the "business end" is packed in behind the body of the breaker where it is not very accessible. Most of the time the door is really just a thin piece of sheet metal that prevents accidentally poking something such as a stick of conduit back into the breaker and some dust protection. The door itself doesn't have anything mounted on it. Things take a big step up though the moment that for instance someone wants to reach in past the breaker to where the stabs are at to do something (if it is even accessible for this). Here obviously "full blown" protection becomes necessary. I know it sounds like this is an utterly stupid act but I can think of a particular customer, a prison, where something happened in the past where some insulated case breakers were actually fused onto the bus work. We could see the stabs were burned a bit while looking from a safe distance and we knew from trying that these breakers simply would not budge at all but we couldn't really see what's going on without sticking a mirror or a camera back there to have a look around. That's obviously where again things get downright dangerous so gloves and full arc flash protection becomes necessary.

Finally we have to consider racking breakers on and off the bus for drawout style breakers. Every time I've ever done it, I've never had a problem. But I've heard horror stories and I've seen the results. Once in a while something goes horribly wrong during racking in (never heard or seen it for racking out). Mostly I've heard of stabs misaligning and folding over to where it bridges to another stab. With some breaker designs I can see this but with others the stabs are not physically long enough to do this so I'm at a loss as to how this kind of thing happens. Suffice to say though that erring on the side of caution is the best approach. So the full arc flash PPE makes sense but I'd have o strongly question whether or not shock protection is needed during this task.

So for even something as simple as a draw out breaker it should be obvious that sometimes arc flash PPE is needed and sometimes it isn't. Similarly sometimes shock PPE is needed and sometimes it isn't. There is no one-size-fits-all case.

A final word can be said for the "under 1.2 cal/cm2" case. If the equipment is not labeled then what is the incident energy rating? Do you go by the tables or is this an indication that it is under 1.2 cal/cm2? No label leads to confusion. And don't tell me you can always tell because you can't. I was just at a plant earlier this week where the issue is that under certain circumstances during operation they would put their largest motor under a heavy load and trip out the system. But the "trip" in this case is to trip out the utility fuses which caused a lot of downtime waiting on a lineman to come out to swap fuses. If the high side of the transformer was 34.5 kV then everything looked to be as it should and this should not be happening. But the actual build looked a whole lot more like a 15 kV system (and thus system voltage was more likely 12.47 kV) in which case the utility fuse was badly miscoordinated with just about everything. The utility couldn't supply that information without getting engineering involved which was going to take longer than I had so I just had to work with what I had. The utility just didn't label anything aside from the low side. And this isn't a local EMC or REA...it is the largest utility in the United States.


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 Post subject: Re: Significance of an Equipment Labels PPE Requirements
PostPosted: Mon Feb 12, 2018 7:59 am 
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Thanks for the response Paul, I fear my question was to wordy, let me try it this way. If a technician were standing inside an arc flash boundary wearing less cals (or no cals of protection) than the labeled equipment called for would OSHA consider it a violation? If they would then wouldn't this make the arc flash risk assessment meaningless because you would always be dressed as if the flash was going to happen. If they wouldn't then the risk assessment makes sense.


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 Post subject: Re: Significance of an Equipment Labels PPE Requirements
PostPosted: Mon Feb 12, 2018 8:24 am 
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Joined: Fri Apr 15, 2011 7:43 am
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Location: Colorado
First I am assuming energized work is being done with exposed equipment (exposed bus). Standing just in the arc flash boundary with PPE less than required is impossible. The AFB has a lower limit of 1.2 cal. That being said, the closer to the energized equipment the higher the incident energy! being closer requires appropriate PPE!
Not having the proper PPE could be a OSHA violation!
On-the-other-hand, if no work other than normal operation then it doesn't matter.


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 Post subject: Re: Significance of an Equipment Labels PPE Requirements
PostPosted: Fri Feb 16, 2018 8:13 am 
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This might sound like splitting hairs here but we have to be clear on the arc flash boundary, similar to the shock protection boundaries.

If there is no exposed equipment then the shock hazard boundary does not exist. The label gives what the shock boundary is, ONLY when it exists.

Similarly if there is no task being performed which could cause an arc, then the arc flash boundary does not exist. The label gives what the arc flash boundary is, ONLY when it exists.

For example if I'm coming to your shop to give you a quote on doing some work and I am simply reading the labels and everything is in reasonably well maintained condition then regardless of your stickers, no arc flash or shock boundaries exist.

Once those activities begin which create exposed equipment or could potentially create an arc, then the shock and/or arc flash boundaries exist and the PPE should be at least present.

Further, NFPA 70E stresses that workers HAVE the equipment when crossing for instance the limited approach boundary. It doesn't specify that it has to be on continuously at that point with good reason. But the limited approach boundary is a different matter. Similarly the arc flash boundary operates in the same kind of way although we don't have two different boundaries.

In utility work a common work rule is to wear gloves "cradle to cradle" (before the bucket in a bucket truck leaves the ground). Under this rule you typically see lineman passing equipment down to a ground man and back again to manipulate hardware or adjust the equipment. On a one man operation, you typically see linemen enter and leave the cradle multiple times to accomplish a task where wearing gloves simply isn't practical. Another rule is that the gloves are on when you are within working distance. So in the latter case the lineman might swing the bucket back beyond the MAD (restricted approach boundary in 70E terms) to loosely attach bolts or screws without gloves while out of hot stick distance before putting the gloves back on and going in to the work zone. The work goes much faster this way and is just as safe but it puts more responsibility on the lineman to use good judgement in deciding when it is safe to remove gloves and when it isn't.

Similarly for industrial workers it is just about impossible to see or do much of anything with gloves and a hood on so a common practice is to leave the gloves and hood off, get everything set up while it is nowhere near a hazard (the restricted approach boundary), put the gloves on, grab the parts, maybe even take one last look and kind of line things up, flip the hood down, and do the job. Then pull back beyond the restricted approach boundary and dump the hood and gloves again if further inspection is needed. The other rule is to remain fully gloved and suited up for the duration of the task. Again in many cases this really isn't very practical and work rules that rely more on good judgement of the person doing the work are both more efficient, safer, and more comfortable.

The onus is on the employer to make sure that irrespective of which work rule you choose that employees are given the proper tools for the job, the proper training, and that there is a paper trail of audits, inspections, and maybe even disciplinary actions showing that there is a continuous and ongoing effort by the employer to ensure that every reasonable effort is being made to ensure that employees are following the work rules. If you have all that in place, you'd be showing compliance.


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