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 Post subject: Inviting suggestions for replacing Category "0"labels
PostPosted: Wed Jun 27, 2018 10:07 am 

Joined: Tue Dec 02, 2014 7:46 am
Posts: 14
We started applying Arc Flash protection at our facilities several years ago, at that time category "0" was a valid Hazard Risk Category. "0" is no longer a Hazard Risk Category. Besides heavy duty non-melting cotton garments for "0" we provided workers 8 cal. and 40 cal. PPE to cover Hazard Risk Categories from 1 to 4.

We are a major beverage company in the Untied States and utilizing a large number of production equipment. After main switchboards incident energy to production equipment drops down greatly to 1 cal. or less than 1 cal. with available fault current only in few hundred amps. If I use table method of 70E then I can apply Category 1 for all equipment upto 240 Volts and category 2 for 480 Volts equipment. Our production line works on 480 Volts. Our equipment are within 70E criteria for Max. SC Current Available and Fault Clearing Time as shown in 70E table methods.

I can label Category "0" equipment to Category 1, good for minimum 4 cal. PPE. Our workers are provided with Category 2 & 4 PPE, so they can use their 8 cal. to work on Category 1. Category 1 does not require Balaclava, that may be an advantage to the users or I just follow 70E table method and label 480 Volts-Category "0" equipment to PPE Category 2. I calculate Available Fault Current and Clearing Time for each equipment through a software and can meet limitation of using 70E tables.

What other members of this Forum will do in labeling of Category "0" equipment or where incident energy is less than 1.2 cal. How they feel about applying Category 2 PPE for all 480 Volts equipment as far 70E tables allow. Your responses and suggestions will be highly appreciated.


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 Post subject: Re: Inviting suggestions for replacing Category "0"labels
PostPosted: Thu Jun 28, 2018 5:10 am 
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Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
SheelPandey wrote:
We started applying Arc Flash protection at our facilities several years ago, at that time category "0" was a valid Hazard Risk Category. "0" is no longer a Hazard Risk Category. Besides heavy duty non-melting cotton garments for "0" we provided workers 8 cal. and 40 cal. PPE to cover Hazard Risk Categories from 1 to 4.

We are a major beverage company in the Untied States and utilizing a large number of production equipment. After main switchboards incident energy to production equipment drops down greatly to 1 cal. or less than 1 cal. with available fault current only in few hundred amps. If I use table method of 70E then I can apply Category 1 for all equipment upto 240 Volts and category 2 for 480 Volts equipment. Our production line works on 480 Volts. Our equipment are within 70E criteria for Max. SC Current Available and Fault Clearing Time as shown in 70E table methods.

I can label Category "0" equipment to Category 1, good for minimum 4 cal. PPE. Our workers are provided with Category 2 & 4 PPE, so they can use their 8 cal. to work on Category 1. Category 1 does not require Balaclava, that may be an advantage to the users or I just follow 70E table method and label 480 Volts-Category "0" equipment to PPE Category 2. I calculate Available Fault Current and Clearing Time for each equipment through a software and can meet limitation of using 70E tables.

What other members of this Forum will do in labeling of Category "0" equipment or where incident energy is less than 1.2 cal. How they feel about applying Category 2 PPE for all 480 Volts equipment as far 70E tables allow. Your responses and suggestions will be highly appreciated.


Since you are updating, note that the table ALSO changed to require a balaclava even for PPE Level 1 (4 ATPV) in addition to the face shield. The purpose of the balaclava is protected to the side of the head where the face shield ends. Note that you are over-rating your panels. PPE is not needed. Simple as that.

The old H/RC 0 actually represented two different cases. It represented cases where the risk (likelihood) of injury was very low although the hazard may be significant, and it represented cases where the hazard was very low regardless of the risk. For example in an informational note elsewhere in the Code it states that normal operation of 600 V class MCC's is unlikely to pose a significant hazard. This is a clear example where although the hazard may be significant, the likelihood of injury is very low. Another example would be working on battery backup systems. Exposed is practically the rule and not the exception with most battery backup systems in switchgear but the incident energy is almost inevitably quite low so this would be an example of the low incident energy case. In either case under the old H/RC system it would be level "0".

With the new system, it's now a 3 table system. The first table addresses likelihood. The second table addresses hazard, and the third table addresses PPE. Thus for low risk (likeilihood cases), the result is that no PPE is needed. In the second case PPE is required but like the NESC (IEEE C2) we get into a strange category with ""Level 0" where it's not really even PPE so to call it "PPE Level 0" is not correct because it is not PPE. So 70E rightfully simply dropped the category altogether.

Finally there are papers presented at ESW on testing of cotton cloth that is untreated. The thermal insulative property of the garment is due to the garment alone and not any fire retardant properties. Thus a 12 oz/yard shirt and pants gives the thermal protection of 8 cal/cm2+ regardless of whether or not it is treated for fire retardant properties. If the thermal rating is exceeded, it will catch on fire or melt regardless of whether it is treated or not. What happens next though depends on the fire retardant treatment. Treated garments will simply extinguish when the flame is removed. Untreated garments continue to burn/melt. Since even bare skin meets the "Stoll curve" requirement, technically buck naked meets "H/RC 0". So no reason to get away from this rating except that if you use it, you need to call it something else.

That brings up the quandry of what to do with "unlabelled" panels. My suggestion is label them for what they are..."<1.2 cal/cm2". you can fit this on a pretty tiny sticker. Since a lot of equipment as you stated is categorically below this, a roll of stickers plastered all over the plant covers a lot of ground very quickly and eliminates the "H/RC 0" enigma. Simple rules to address lighting panels (all the 120 VAC control panels, lighting panels, etc.) which doesn't meet the criteria necessary for analysis under IEEE 1584 or is even questionable if it is at least 208 VAC (due to the lack of data), can be quickly estimated with some simple criteria without software, and marked appropriately as either "<1.2 cal/cm2" or "PPE Level 1" as necessary using the table-based approach given in NESC which addresses equipment up to 300 VAC with what is known in 70E as "PPE Level 1" for anything that you can't categorize as "Level 0". If you insist on a level I guess just give it your own house name such as "Level Low".

As to the nonmeltable category...this is kind of tricky. Technically below 1.2 cal/cm2, there are no rules under 70E currently and the nonmeltable category somewhat goes away. However as soon as we get above that incident energy, 70E clearly states that nonmeltable undergarments are necessary when you are wearing 8 ATPV or 40 ATPV PPE. So unless we want to get into a lot of potentially embarassing and awkward situations when putting the stuff on, it's a lot easier to just maintain the nonmeltable clothing category for electrical workers.


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 Post subject: Re: Inviting suggestions for replacing Category "0"labels
PostPosted: Wed Jul 18, 2018 12:34 pm 
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Joined: Sun Jan 04, 2009 5:00 pm
Posts: 285
Location: Louisville, KY
Many of our clients use the HRC 0 labels (grandfathered) and train to wear the HRC 2 without a faceshield.

There is no real reason to change them unless the study indicates they should be changed.

Some will differ with this opinion. The worker is protected and the information useful to help make a decision to protect, OSHA would likely agree.

Hugh Hoagland


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 Post subject: Re: Inviting suggestions for replacing Category "0"labels
PostPosted: Wed Jul 18, 2018 3:18 pm 
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Joined: Sat May 17, 2008 5:00 pm
Posts: 88
I have seen some simply label <1.2 cal/cm^2 and also labels using "Level 0" as a site specific PPE


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