Arc Flash Labeling FAQ—Part Two
/Today’s installment investigates the conditional questions of the “what” and “when” of arc flash labeling—what needs labeling and when is it necessary to update those labels?
2. What needs labeling?
General: This question often comes up because the level of labeling can have a significant impact on financial outcome an arc flash study. Do you need to spend the money to label every single disconnect and panel?
In a general sense, the NEC and the NFPA 70E-2018 both share a common perspective on the subject. Comparing the references from the two standards, they are virtually identical: The NFPA 70E puts it this way—
"Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and that are likely to require examination, adjustment, servicing, or maintenance while energized shall be marked with a label … " (NFPA 70E-2018 Art. 130.5(H))
The NEC is nearly verbatim to 70E however it adds this, “… shall be field or factory marked to warn qualified persons of potential electrical arc flash hazards.” (NEC Art. 110.16(A)).
Low Energy Systems. Do we need to label low energy equipment? In the past, it was accepted practice to exempt low voltage equipment from arc flash hazard analysis and the consequent labeling. This was based on a statement in the 2009 edition NFPA 70E which specifically exempted arc flash hazard analysis for systems in which the circuit is rated at 240 V or less, is supplied by one transformer, and the transformer supplying the circuit is rated at less than 125 kVA (NFPA 70E-2009 article 130.3 Exception No. 1). Newer editions of 70E have removed this exemption. So what is to be done with this lower energy equipment? One can still appeal to the de facto standard on arc flash analysis, IEEE 1584-2002 for it maintains the exemption. In 1584, we find this note on the process of arc flash incident energy analysis, “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.”
An argument, therefore, can still be made for excluding certain low energy devices from the requirement to label the equipment. However, a serious issue remains—how will the worker interpret the absence of labels? Having unlabeled equipment leaves open room for confusion that may increase the risk to electrical workers. Somehow, either in the training process or by other means, the worker needs to be able to interpret the meaning of this absence. Does the missing label indicate intentional absence because it has been determined to be safe low energy equipment? Or is the absent label due to a new unlabeled device that may pose potentially dangerous energy to the unwary worker? If it is the latter condition, it is possible the worker might assume it to be low energy equipment and the inadvertently exposing them to hazardous energy unprepared.Consistency seems to be the better policy. Label everything, even if it is some generic low-level label. This would prevent dangerous misunderstanding.
We would underscore the importance of ensuring that we not ignore low-voltage systems lest confusion place workers in unnecessary danger. Even though systems may have relatively low-voltage they may at the same time have high available fault current and thus present a genuine arc flash risk. It must be remembered that in most cases it is difficult to sustain an arc at very low-voltage, however, according to the IEEE 1584 there are conditions where low voltage arc flash may be sustained,“Arc faults can be sustained at 208V and have caused severe injuries with very high short-circuit current applications in meter enclosures…” (IEEE 1584-2002 page 25). Thus, for most systems labeling will be necessary for all equipment that requires examination, adjustment, servicing or maintenance while energized except for very low-voltage equipment (less than 240 V) systems that are fed by transformers of less than 125 kVA.
No Labeling? The New Exception: Believe it, or not, labeling is now optional—sort of! NFPA 70E Article 130.5(H) Exception #2 says, “In supervised industrial installations where conditions of maintenance and engineering supervision ensure that only qualifed persons monitor and service the system, the information required in 130.5(H)(1) through 130.5(H)(3) shall be permitted to be documented in a manner that is readily available to persons likely to perform examination, servicing, maintenance, and operation of the equipment while energized.” The whole point of labeling electrical equipment is to provide readily available and understandable safety information to enable the worker to make effective risk assessment and PPE decisions. In our day of technology gives us options other than the old-style label method . You could put it in a manual, you could put it in a computer database, you could attach a bar code or QR code that the worker can access the information with a smart phone, or some other option that meets the requirements.
However, notice that there are a couple of caveats. Firstly, this exception only applies “where conditions of maintenance and engineering supervision ensure that only qualified persons monitor and service the system.” The term “qualified” carries with it the assumption that those workers have sufficient training to be able assess the hazard and make informed risk reduction methods. Consequently, the training of these qualified employees must include the ability to assess whatever alternative method of information delivery that is used. Without this training, the label substitute would not pass the requirement that the employees servicing the equipment be qualified
The second requirement is that the documentation be “readily available.” What if the documentation is maintained at a distance from the work location or it is difficult to access or digest? Then the likelihood that the worker would use the information is low and would then fail the “readily available” requirement. So if an alternative method is used to document the arc flash safety information, extra care must be taken to ensure that availability is maximized or it will be ineffective. One observation, it is hard to beat the accessibility and understandability of properly placed and designed labels.
It appears that a push for the use of alternate methods of documentation diverging from the standard label method may be driven by economic pressures to avoid the expense of producing and installing the labels. We must be cautious not to sacrifice safety for financial gain. If a serious arc flash occurs and workers are not properly protected the medical and other expenses occurred by the event may exceed any cost savings by a huge margin. It may be that in the near future, an alternate method of documentation will supplant the typical arc flash label, but so far, effective alternatives methods of documentation are not yet evident.
3. When do the labels need installation/updating?
There are a couple of possibilities to consider while investigating the “when” question. Firstly, when do you need to start labeling your facility? We run into folk who assume there is some kind of grace period and a consequent completion date somewhere in the distant future. Alternatively, they expect that existing equipment may be “grandfathered-in.” That kind of grandfather clause may be true of electrical code issues as it pertains to the NEC, but does not apply to the NFPA 70E. The essential difference between the NEC and 70E is that the purpose of the NEC is to protect equipment while 70E protects people. Safety can never be grandfathered nor compromised, therefore there is no grace period and no grandfathering of old installations.
Next, lets consider the periods required for updating the labels. Are they installed once then forgotten? Nope!
To substantiate this answer, we have to consider two related issues: (1) the incident energy analysis and (2) the accuracy of the labels themselves. It is safe to say that most arc flash labels are founded upon the engineering-based incident energy analysis. Incident energy is essentially the amount of heat energy that may be applied to a workers unprotected body—especially the face and chest area—in a potential arc flash. This is extremely useful information since once you know the potential severity of the arc flash, you are then able to estimate what kind of protection is required to keep workers protected from the potential arc flash. Incident energy involves engineering evaluation. According to NFPA 70E Article 130.5 (G) “The incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis. The incident energy analysis shall also be reviewed for accuracy at intervals not to exceed 5 years.” The accuracy of arc flash estimates depends upon the accuracy of the data collected from the existing system. If the system changes, the arc flash incident energy is likely to change—possibly in a more dangerous direction. So, if the system changes or if five or more years have passed, the incident energy analysis will need to be updated and also the labels dependent on them if found to be inaccurate. Note that this does not per se require complete relabeling of a facility every 5 years, but it may be that wholesale relabeling might nevertheless be the most efficient method of handling the changes uncovered
The other issue, is of course, the actual label accuracy itself. According to NFPA 70E Article 130.5(H) Exception No. 1, “Unless changes in electrical distribution system(s) render the label inaccurate, labels applied prior to the effective date of this edition of the standard shall be acceptable if they complied with the requirements for equipment labeling in the standard in effect at the time the labels were applied.” If the labels are compliant at the time they were installed AND the labels continue to accurately reflect the current state of the systems they need not be changed. Although they technically may not need to be changed, it may be more practical to change them anyway. Unless the changes are very minor, it may end up being more time consuming to sift through the those needing changes and those not than to make wholesale changes.
