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 Post subject: Labels below 480V level?
PostPosted: Fri Jun 02, 2017 7:42 am 
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Is labeling of equipment below 480V level required? If so are all panels required to be labeled even at 120V? If so can you a generic label be applied or are calculations required to be performed?


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 Post subject: Re: Labels below 480V level?
PostPosted: Fri Jun 02, 2017 10:05 pm 
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NEC does not have a voltage cutoff but if there is no recognized hazard a label wouldn't make sense. NEC is the mandatory (regulatory) requirement not 70E and under that Cide a very generic "Warning - Arc flash hazard may exist" label is sufficuent. And not all equipment needs a label. See NEC.


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 05, 2017 7:01 am 
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I believe the answer should be yes, but with a qualifier.

Consider this: if the equipment may at some point be opened to work on, then I'd label it with the proper arc flash and voltage warning label. If you believe there's a chance someone could remove a cover, then they are exposed to both shock and arc flash hazards. And yes, there's a reasonable argument to be made to not label certain pieces of equipment, but if you consider the possible long term problems, spending a few dollars on labeling could prevent trouble going forward.
So if someone were to be injured, there's a good possibility that this event could trigger a trip to court. Even though you may be able to prove the injured person was not qualified or should not have been working in this equipment, juries often ignore that fact and award the injured person damages. However, if equipment has been properly labeled, making a case that you were somehow negligent is much more difficult.


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 05, 2017 10:56 am 
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Specifically for NEC it's 110.16. Recently (2017 edition) it has been split into two sections. The key wording in section (A) of the 2017 edition (or the whole section in 2002 through 2014 editions) is: "electrical equipment located in other than dwelling units that will likely require examination, adjustment, servicing, or maintenance while energized." It then gives a list of examples such as switchboards, MCC's, meter sockets, industrial control panels, etc. They are examples only and the list does not specifically mandate a label on anything on the list and there can be equipment not on the list that requires a label. There is some "grey area" here. For instance the word "likely" is a bit vague. A good general rule of thumb that I use is whether or not it will require "examination, adjustment, servicing, or maintenance" more than once a year. If it is less than that, a label probably isn't required and someone can take the extra time to look it up. Also the words "while energized" mean just that in the general term, and voltage testing is exempted. So for instance no need to label motor peckerheads and other types of termination boxes on equipment where the general practice is to shut the power off before opening and servicing it. This also avoids maintaining labels in what are generally rough service environments.

The new 110.16(B) requirement is for "service equipment" only and only applies to service equipment rated 1200 A or more...this is the rating of the equipment, NOT the protective device rating. So an 800 A MCC protected by a 1200 A fuse doesn't count. With this equipment it can either be labeled with the voltage, available fault current, overcurrent opening time based on the available fault current, and the date the label was printed, or else with an arc flash label.

Nowhere in either of these is there a voltage cutoff. Some plants have a practice of for instance putting something in their work instructions, procedures, etc., that unlabeled panels have an assumed incident energy level and this certainly cuts down on the amount of required labels. Generally this is the lowest ATPV PPE used by their electrical staff (1.2, 2, or 4 cal/cm2). It is something of an NEC violation though although some of those same plants just put a very generic sticker on (<4 cal/cm^2 for instance). Again...it avoids a lot of unnecessary labels.


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 19, 2017 9:14 am 
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Voltage level should not be used as an indicator to install an arc flash label or not. Downtown Seattle has 208 Volt Network vaults with arc flash energy over 40 Cal/cm2. They have fault currents over 100 kA. These are extremely dangerous places to work in.

I answer has more to do with what IEEE 1584 says. Currently on page 6, it states, "Equipment below 240 V need not be considered unless it involves at least one 125 kVA or larger low impedance transformer in its immediate power supply."

The 125 kVA cut off has been called into question and it is rumored that in the next version of IEEE 1584, this 125 kVA cutoff will be reduced. Our Arc Flash labels serve two purposes. They warn the work of the Arc Flash Energy Level and the Shock Hazard. Our labels also state voltage level and the minimum Insulated Glove Class. Our new labels will list the maximum available short circuit current as well.

Not labeling all major electrical equipment can lead to confusion. If a piece of equipment is not labeled, is it because the arc flash energy is low (less than 1.2 Cal/cm2) or is it new?

We recommend labeling all of the major electrical equipment shown on the one line and any additional equipment that will likely require servicing while energized.

_________________
Robert Fuhr, P.E.; P.Eng.
PowerStudies


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 19, 2017 9:56 am 
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Great discussion. I have a few things to add.

The 125 kVA cut off IS changing. It is not cast in stone as to what the final language will be (if any). The present thinking is to have it in terms of current not kVA. That way long 208 V. lines from larger transformers may also be excluded. However this may not be the final form. There is also discussion just to eliminate the exception and leave it up to the user's risk assessment. The problem would be if the circuit is excluded, what goes on the label?

I conducted a survey right here a few years ago and used it as the basis for an article in Electrical Contractor Magazine regarding what get's labeled. Here it is: http://www.ecmag.com/section/safety/such


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 19, 2017 10:41 am 
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Jim Phillips (brainfiller) wrote:
There is also discussion just to eliminate the exception and leave it up to the user's risk assessment. The problem would be if the circuit is excluded, what goes on the label?


True that if it is excluded, what label (if any) should it get. Traditionally we don't go around putting "no hazard" labels on things. Anyone who has ever participated in a formal risk assessment method would roll their eyes at the idea of labelling things that are not hazards. It's not unusual to have 5-10 PAGES of risk assessment spreadsheets where every single row is a "no hazard" entry.

However what I believe that the "exception" helps with is another case. Right now we target the Stoll curve at the face/chest area as a lower cutoff for PPE more or less. So if the hazard is less than this threshold, there is no PPE required. We can't honestly say that there is no hazard but take for instance a real case documented by OSHA where an IT worker had an IEC-style 120 V plug explode and was hospitalized for burn injuries to the fingers or another one in which someone received burn injuries from a 120 V plug while inserting it into a defective power strip where a metal cover on the strip was loose. It wasn't documented whether or not either of these injuries were 2nd degree burns or greater but currently the cutoff following ASTM 1959 and IEEE 1584 allows second degree or greater burns on the arms and hands anyways...the face/chest area is the "cutoff". So any arcing fault causing a burn that is less than that criteria (second degree or greater burn at face/chest area) is not addressed by IEEE 1584/ASTM 1959.

So I'm not sure of the wording here whether we call this a comparable risk or minor risk or minor hazard or something...it's obviously a hazard but not one that we intend on addressing by any standard right now. Sort of like paper cuts...they are out there in every office environment but we don't ban paper or require office workers to wear cut resistant gloves as a consequence.

This doesn't even address the problem that at low (<250 VAC) voltages, arcs tend to not be ver sustainable/stable and so the IEEE 1584 measurement method for instance breaks down. So far without a way to calculate when this happens we will probably have to resort to a consensus-built table.

Right now though there is no standard describing what arcing fault incidents are "safe" (below the above threshold category) or "unsafe". Getting rid of the exemption in IEEE 1584 leaves everyone in a lurch...there isn't an acceptable definition of a lower cutoff for anything. So even 1.5 V "AAA" batteries would need an arc flash analysis. Granted this is a prety silly excample but that's exactly where we are headed if the exemption goes away entirely.


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 Post subject: Re: Labels below 480V level?
PostPosted: Mon Jun 19, 2017 11:55 am 
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Thanks Paul. I'm pushing to keep something in IEEE 1584 as a lower exemption but since it is a consensus standard, it's up to those voting and not everyone is in agreement (no surprise). The users need some kind of guidance. Once we get past the first balloting and comments, the direction will become clearer.


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