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 Post subject: Flash Protection Boundary
PostPosted: Wed Dec 09, 2009 10:11 pm 
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Location: Elyria Ohio
We have at our facility a complete hazard analysis but need some clarifications. We understand the 5 levels of protection, but have disagreements on the flash protection boundaries. My question is: If we have a Level 0 label marked with a flash protection boundary of let's say 6", does that mean even if you cross the 6 inch from exposed conductor boundary, you don't need additional ppe? This doesn't make sense to me? :confused:


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PostPosted: Thu Dec 10, 2009 7:05 am 
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JPS wrote:
We have at our facility a complete hazard analysis but need some clarifications. We understand the 5 levels of protection, but have disagreements on the flash protection boundaries. My question is: If we have a Level 0 label marked with a flash protection boundary of let's say 6", does that mean even if you cross the 6 inch from exposed conductor boundary, you don't need additional ppe? This doesn't make sense to me? :confused:


We had the same confusion in our plant. You need to separate the two hazards in your mind - Arc Flash and Electrocution as they are independant of each other (see 70E 130.2 (B) FPN). The electrocution approach boundaries are found in 70E Table 130.2 (C) and are based on voltage level, qualified/unqualified and moving/fixed circuit part. The PPE for electrocution is based on task and can be found in 70E Table 130.7(C)(9,10,11). From my understanding this is not currenty required as part of the cabinet labeling. The cabinet does need to be labeled with either a catagory of PPE - Or - Available incident energy acording to NFPA 70E 2009 130.3 (C) for Arc Flash. So according to my understanding of your question, you need to wear the Catagory 0 PPE to cross the 6" Arc boundary and may need additional voltage rated PPE based on the task being performed.


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PostPosted: Fri Dec 11, 2009 10:03 am 
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130.3(B)(1) ...PPE shall be used for any parts of the body that are closer than the distance at which the incident energy was determined.

To me this if taken literally, this implies that if the energy is calculated at 18 inches and is catetory 0, if you are closer 18 inches you need PPE. However, the Arc Flash Protection Boundary is where you reach 1.2 cal/cm2 which is where you need PPE and in your example this is 6 inches. Seems like another NFPA 70E contradiction.

Also 130.7(C)(6)(c) ...Hand and arm protection shall be worn where there is a possible exposure to arc flash burn...

130.7(C)(1) states ....All parts of the body inside the Arc Flash Protection Boundary shall be protected.

Yet table 130.7(C)(10) does not suggest protection for the back of the head i.e. balaclava sock, for category 1 or 2.

Confusion? It is understandable. Everyone here is pretty good at providing their interpretations about some of these contradictions. Hopefully it helps.

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PostPosted: Fri Dec 11, 2009 12:35 pm 
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Location: Connecticut
Let's really confuse some people.

Let's say I have an IE of 7.8 cal/cm2 at 18". Well an 8 cal protection scheme will cover me. (Normally referred to as Cat 2 but you shouldn't mix Tables and Calcuations)

But what is the IE at 6", or 4"? Which is where you might find yourself working at?

Or what is the IE at 30" which is where your face, or other body parts may be?

The point I am making is we all make generalized assumptions for working distances - but does everyone really understand the true meaning of them?


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PostPosted: Fri Dec 11, 2009 1:54 pm 
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John, Great comment! - You hit on a very serious problem with both the tables and calculations. Each assumes the incident energy (and resulting level of PPE) is based on a specific working distance - often 18 inches.

People just look at the label and think... ah yes, the label says category 2 / 8 cal/cm2 - that's all I need. .... and then proceed to work up close and personal with the electrical equipment, sometimes within a few inches not realizing the incident energy at the reduced distance goes up exponentially.

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PostPosted: Fri Dec 11, 2009 2:55 pm 
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Paragraph 4.9 of IEEE-Std 1584 says:
Quote:
Arc-flash protection is always based on the incident energy level on the person’s face and body at the working distance, not the incident energy on the hands or arms. The degree of injury in a burn depends on the percentage of a person’s skin that is burned. The head and body are a large percentage of total skin surface area and injury to these areas is much more life threatening than burns on the extremities.


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PostPosted: Fri Dec 11, 2009 3:09 pm 
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Thanks, that response makes sense.


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PostPosted: Fri Dec 11, 2009 3:21 pm 
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Thanks, I agree, and since I have seen many vid's and pics about this, I will advise to cover any body part within the fpb, personally for me, it will be at least an 8 cal/cm2 face shield and hard hat.


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PostPosted: Fri Dec 11, 2009 4:52 pm 
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Arc Flash Protection and working distance

JPS wrote:
We have at our facility a complete hazard analysis but need some clarifications. We understand the 5 levels of protection, but have disagreements on the flash protection boundaries. My question is: If we have a Level 0 label marked with a flash protection boundary of let's say 6", does that mean even if you cross the 6 inch from exposed conductor boundary, you don't need additional ppe? This doesn't make sense to me? :confused:


First, I assume by five levels of protection you mean Hazard risk categories (HRC) 0,1,2.3,4, & 5. This is based on tasks listed in NFPA 70E-2009 Tables 130.7 ( C) (9). Please note you can only use these categories if the system you have is within the parameters of the notes listed after the table for each type of equipment. HRC description is based on a working distance of 18 inches.The level of PPE ( personal protective equipment) recommended is based on preventing onset of a second degree burn. From the description you have given a flash protection boundary of 6 inches indicates that incident energy was calculated. if that is true, then you cannot use HRC tables for labeling or selection of PPE. Flash protection boundary of 6 inches indicate there is a hazard of getting a second degree burn. It does not mean there is no injury potential after 6 inches. As a good practice, only qualified electrical workers should enter within limited approach boundary ( see 70E table 130.2 (c) and should wear proper PPE ( I personally recommend a minum 4 cal/cm2 shirt and pants) Does it adress your question? Electrical safetyman


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PostPosted: Fri Dec 11, 2009 7:13 pm 
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We consider level 5 an unacceptable risk, and use engineering controls to extend the work distance and/or by shutting off the power from the source in our powerhouse. The five levels are "0", "1", "2", "3", and "4". To save on money, we decided to purchase 0, 2 and 4 for our site. Our hazard assesment was done in 2003 and our sticker gives us both the level of PPE to wear, flash protection boundry (fpb), and a restricted aproach boundry. Exmple of our HRC 0 means all cotton long sleeve, safety glasses, etc. etc. A level HRC 2, is an 8 cal/cm2 face shield, hardhat, 8 cal/cm2 coveralls, etc. etc. We use a 12 inch restricted aproach boundry as a conservative distance for all our 480 volt panels However, under this is a flash protection boundry, fpb, listed that varies from 6 inches on up. My question was what do you do if, for example, you have a level 0 and it lists a fpb of 6 inches and you are troubleshooting and you may have to get your face within the 6 inches. Of course I am wearing gloves based on voltage because I am in the restricted boundry for shock hazard, however, what should I have on my head? HRC 0 has no head protection listed. Do you put on the balaclava and / or 8cal/cm2 faceshield and hardhat?, or nothing. Personally, I always have on my 8cal coveralls while working on the floor, and if I get up close and personal, I would wear the arc-rated faceshield and hard hat, but need to know what is the right thing to do. Any help?


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PostPosted: Sat Dec 12, 2009 12:31 pm 
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Arc Flash limits of approach vs volage limits of approach

What level of PPE is required?
What does category 2 mean?
Standards, testing,
garment information,
selection and application questions

The testing is based on ASTM tests
Garments should be marked with categories and Calories/cm squared
The Limited Restricted and Prohibited (LRP) are often confused with Arc Flash Incident Energy Limits of Approach
These three aproach boundaries are related to VOLTAGE and are independant from Arc Flash IE
These LRP boundaries are related to qualified and non-qualified workers in terms of the task being performed relative to avoiding shock and live contact
In my opinion the tables should only be used if you read the notes and then only as a bounding guideline until such time that an Arc Flash Analysis has been completed
The Tables have several notes that limit their actual safe application and often the notes are not read and or understood
Once the AFIE study is completed the tables should not be used rather selection of PPE is based on the calculated incident energy levels set in incremental values and is intended to offer protection to limit injuries to a second degree burn.
The first 18" typically has such a high level of energy up to 35,000 deg F that the PPE application measurement really starts at 18". Any part of the body from 0 to 18" is unlikely to survive and will likely result in a meltdown or third degree burns as a minimum
After 18" the PPE is intended to reduce the injury worst case to a second degree burn (which is still very serious and will always result in hospitalization and lost time)
When testing voltage we recommend using 12" extended leads and 6" probes, and a fused section (see Fluke) on any test instruments to allow a worker to keep their hands and arms back from the live surface 18 to 20"
When in doubt maximize your PPE within reason and comfort and always perform a hazard analysis and risk assemment

John B. Salmon, RME
Registerd Master Electrician

President A.R. Milne Electric Ltd.
Waterloo, Ontario Canada
Arc Flash and Workplace Electrical Safety Specilists


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PostPosted: Mon Dec 14, 2009 4:18 pm 
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I'm glad you understand that the closer you get the hotter it will be! As was previously stated, any part of the body that crosses the AFB must be protected. It also says that the hands and arms may need more protection because they are closer.

So, what is the HRC #0 protection for the head? NADA! HMMM So, you apparently know that it is more dangerous, now it's time to put the gray matter to work. To hell with NFPA 70E and all the categories... why are you getting your face within 6" of an energized circuit? I would back up and re-assess what I'm doing. I may be ugly but I want to keep my eyelids! :eek:


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