Yes, for example for a 300 bus industrial factory with 13.8 kV, 4.16 kV and 600 V equipment, 65% of the PPE categories stayed the same, 34% PPE categories increased with the new 2018 standard and 1% showed a decreased PPE category.įor enclosure size, do you mean circuit breaker enclosure size?Įnclosure size represents the size of the panel or mcc/switchgear cell in which the arc flash can occur (metal box).įor areas where I am contracted to perform an arc-flash, but I do not know the electrode configuration or the enclosure size, what would you recommend as a default?Ĭhoose a reasonable worst case electrode configuration based on your equipment type (if fuses VS breakers), then enclosure size based on typical values from IEEE 1584 or EasyPower library. Have you performed a case study on an actual facility using both the old method and the new method, and if yes, how different were the results? Lee Method is too conservative for very high voltage values, but could also be used in the 15-25 kV range. Which is the method to work over 15kV from point of view of the snatdard and from EasyPower.ĮasyPower has a built-in module to calculate arc flash energy above 15 kV based on ArcPro curves. In general, the energy is much higher for medium voltage and for equipment with HCB configurations when compared to the 2002 results.

It is hard to predict and depends on many factors. How are the AF results comparing with the new standard in comparison to the old one? NFPA 70E tables should be updated in the future to updated PPE categories based on the new IEEE 1584-2018 results. How will tables in 70E be affected by the new calculation method, particularly for troubleshooting equipment under 600V? It is up to sound engineering judgement to choose reasonable assumptions that represent reality.

G.43) configuration on a MCCB and much more likely to uccur in the VCB (fig. True, but an arc flash is very unlikely to occur in the HCB (fig. Do you have recommendations on how electrode configuration is determined? IEEE anex also shows HCB is possible in a 600V MCCB.this is very confusing. Is the shallow vs typical cutoff voltage less than 600V or less than or equal to 600V? Just to be sure: a fused switch panel will be VCB? Sticker with shock hazard information only. Use the enclosure size of the smallest bucket in the arc flash equations & put an identical label on each column of the MCC, depending on the client.įor less than 2kA and 240V buses, what stickers do you put? 0 PPE ? How are you addressing labelling of empty MCC spare bucket sections which are larger than a single bucket? If there is voltage below or equal to 240 V present in the cabinet and the available short-circuit current is equal or above 2 kA, yes. If there is voltage above 240 V present in the cabinet, yes. The arc flash study could be applied to SF6 panel enclosed? See the sensitivity analyses in the presentation PDF.

The energy changes alot when compared to the 2002 version. There is not enough energy to sustain an arc.Īre there many changes in incident energy or is it roughly the same? Since there is no arc flash danger at this level, no cal or af boundary needs be specified. What Cal and AF boundary shall be label equipment that is 240v nominal or less with less than 2000a short circuit current? What is the electrode configuration if it is fuses? Typical dimensions can be found in IEEE 1584-2018 tables or in the EasyPower default library. For conservative assumptions, use small enclosure sizes. Worst-case results are obtained with smaller enclosure sizes. When barrier dimensions can't be practically measured (maybe due to lack of access) would there be some conservative assumptions for measurements based on configuration/voltage level/etc.? Or would the differences in sizes necessitate accurate measurements of enclosure?

Is this assumption stated in the standard or a practice you're recommending? You mentioned using a 2s assumption for the main service entrance equipment due to assumption the utility can change their upstream protective device without notice. Download a Free Demo Simon's Presentation (PDF)ĭownload Presentation Answers to Q&A Following Live Webinar Question

Arc flash boundary 2018