It is currently Wed Nov 22, 2017 10:38 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: 70E 4 foot rule reduced in 2009 ?
PostPosted: Sun Dec 07, 2008 7:21 am 
Offline

Joined: Fri Oct 17, 2008 2:24 am
Posts: 3
It looks like the 2009 70E cut the use of the 4 foot rule for the arc flash protection boundary from 300 kA-cycles to 100 kA cycles. This does not seem to line up with Lee's equations that have now been moved to the annex. It appears they are trying to make the 4 foot rule so restrictive that you can't use it and must perform calculations.

Any thoughts or ideas?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Sun Dec 07, 2008 12:02 pm 
Offline
Arc Level

Joined: Thu Jan 10, 2008 8:49 pm
Posts: 480
Location: New England
100KA is a lot more restrictive but for most installations still acceptable. If you assume that a molded case breaker in its Inst trip range will have a 2 cycle clearing time, then fault current could equal 50KA, which is still much higher than is found on most medium and small industrial installations.

The problem that I anticipate is that 2 cycle is a bit quick for draw out switchgear breakers. If we give 4 cycles for the breaker the resulting 25KA would be on the low side.

NFPA is again showing that they don't have a good handle on the real world installations. First, forcing manufacturers to do a full blown analysis is excessive and too much of a financial burden to be reasonable.

What NFPA should have done was realize that it is easier for the owners to comply with distance than it is with clearing time and fault currents. They should have just established a realistic safe zone as a default condition. I would have recommended 65KA, 8 cycles, and 10 feet. I haven't worked the math on this but you get the gist. Just establish a default distance that is far enough to safely protect against most conditions typically found.

The big difference is that then this default boundary would be in the code and thus acceptable as a default without analysis. Increasing the AFB has little real financial impact on manufacturers and in the vast majority you don't have or need untrained employees that close to live work anyway.

Unfortunately NFPA doesn't seem to grasp the need to define regulations that are also easy to implement. They pick 2 cycles which is extremely fast and at the best is only available for fuses and molded case breakers and don't realize that switchgear is typically slower. When given the opportunity to change, they choose to keep the same 4 feet distance and the same 2 cycles and just reduce fault current. Where they could have kept the original 300KACycles and just increased the default distance.

I find it very sad that we are forced to follow regulations created by institutions like this that lack real world practical experience. But what is far worse is the impact that such shortcomings have on US manufacturing.

So to answer your question, I don't think NFPA changed the rule with the intent of forcing companies to do an analysis. I think they realize that most will not have the financial resources and that the default tables can be designed to provide adequate safety. They probably were correct in realizing that 300KAC was too high for a 4 ft AFB, but they got it wrong - again, by lowering the KA * Cycles, instead of raising the ft AFB. I believe this to be a simple lack of common sense rather than a clandestine plan.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Sun Dec 07, 2008 12:57 pm 
Offline

Joined: Fri Oct 17, 2008 2:24 am
Posts: 3
Thanks Haze, that makes a lot of sense - instead of insisting 4 feet is good and adjusting the limits lower, they should recoginze the limitations seem to be more important and should have adjusted the boundary higher - it's only for those not dressed in PPE and performing the work anyway. You should work for NFPA!!


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Dec 08, 2008 7:07 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
haze10 wrote:
100KA is a lot more restrictive but for most installations still acceptable. If you assume that a molded case breaker in its Inst trip range will have a 2 cycle clearing time, then fault current could equal 50KA, which is still much higher than is found on most medium and small industrial installations.

The problem that I anticipate is that 2 cycle is a bit quick for draw out switchgear breakers. If we give 4 cycles for the breaker the resulting 25KA would be on the low side.

NFPA is again showing that they don't have a good handle on the real world installations. First, forcing manufacturers to do a full blown analysis is excessive and too much of a financial burden to be reasonable.

What NFPA should have done was realize that it is easier for the owners to comply with distance than it is with clearing time and fault currents. They should have just established a realistic safe zone as a default condition. I would have recommended 65KA, 8 cycles, and 10 feet. I haven't worked the math on this but you get the gist. Just establish a default distance that is far enough to safely protect against most conditions typically found.

The big difference is that then this default boundary would be in the code and thus acceptable as a default without analysis. Increasing the AFB has little real financial impact on manufacturers and in the vast majority you don't have or need untrained employees that close to live work anyway.

Unfortunately NFPA doesn't seem to grasp the need to define regulations that are also easy to implement. They pick 2 cycles which is extremely fast and at the best is only available for fuses and molded case breakers and don't realize that switchgear is typically slower. When given the opportunity to change, they choose to keep the same 4 feet distance and the same 2 cycles and just reduce fault current. Where they could have kept the original 300KACycles and just increased the default distance.

I find it very sad that we are forced to follow regulations created by institutions like this that lack real world practical experience. But what is far worse is the impact that such shortcomings have on US manufacturing.

So to answer your question, I don't think NFPA changed the rule with the intent of forcing companies to do an analysis. I think they realize that most will not have the financial resources and that the default tables can be designed to provide adequate safety. They probably were correct in realizing that 300KAC was too high for a 4 ft AFB, but they got it wrong - again, by lowering the KA * Cycles, instead of raising the ft AFB. I believe this to be a simple lack of common sense rather than a clandestine plan.



Every member of the 70E committe has more real world experience than you think they do, instead of bashing why dont you get involved? How many 70E meetings have you attended? How many proposals have you submitted?

I agree with your points about the AFB, but you need to do some more research, I suggest you download and read the ROP's for the 2009 70E, there you can see the proposals (Just like the ones you are suggesting) and why they were rejected.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Dec 08, 2008 7:36 pm 
Offline
Arc Level

Joined: Thu Jan 10, 2008 8:49 pm
Posts: 480
Location: New England
Zog,
I will be the first to admit that I am cynical. I'm getting to be an old man and tired of seeing the loss of our manufacturing base and the economic equality it has brought to so many families. Yes, I am bashing the NFPA. I feel they that they do not have a practical sense of compromise, and I think that feeling is shared by others on this board who face the same day to day issues that I do.

This would be some suggestions I have for the NFPA:

1) Refuse to seat any person who is associated with an organization that is going to profit from the rules the committee passes.

2) Stop issuing new editions when there are no safety motives for doing so. If 70E from 2009 covers all that is necessary, and there no longer exists a statistical safety hazard - then don't print a new edition in 2013 and save us all the cost and effort of meeting a new edition.

These are both common sense requests - how do you think they would be received?

No I don't know why NFPA chose to reduce the Amp Cycles instead of raise the distance. But if you ask any engineer involved in industry, I think all will tell you its easier to adjust the distance than change all their fault current or overcurrent devices. So for whatever logical reason based upon their years of manufacturing experience the NFPA perfers the former - I think it is contrary to what the rest of us engineers in industry would have chosen. If that is true - then both parties can't be correct. So how do you decide who is right - the committee that manufactures nothing - or those of us trying compete in the market place?

I am hoping that NFPA takes advantage of this forum and starts reading it. Then they can get a flavor for our issues. I write my Senator all the time, but he just sends me back a form letter saying he disagrees with my position. Maybe if I write him more he will change his mind.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Dec 09, 2008 6:53 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
haze10 wrote:
Zog,
I will be the first to admit that I am cynical. I'm getting to be an old man and tired of seeing the loss of our manufacturing base and the economic equality it has brought to so many families.


I agree, I used to work in Detroit and relied on the automotive industry, sad to see what is happening there, sad to see what has happened to the value of my home there, but not the 70E's fault, sadder still to see someone in a brun unit from an arc flash, I have seen the 70E rules save lives, I can prove it to you.

haze10 wrote:
This would be some suggestions I have for the NFPA:

1) Refuse to seat any person who is associated with an organization that is going to profit from the rules the committee passes.

2) Stop issuing new editions when there are no safety motives for doing so. If 70E from 2009 covers all that is necessary, and there no longer exists a statistical safety hazard - then don't print a new edition in 2013 and save us all the cost and effort of meeting a new edition.


Now you are pointing out many things that need to change, and most of them are valid points, you have some good ideas, but the standard needs to be revised to make it better.


haze10 wrote:
No I don't know why NFPA chose to reduce the Amp Cycles instead of raise the distance. But if you ask any engineer involved in industry, I think all will tell you its easier to adjust the distance than change all their fault current or overcurrent devices. So for whatever logical reason based upon their years of manufacturing experience the NFPA perfers the former - I think it is contrary to what the rest of us engineers in industry would have chosen. If that is true - then both parties can't be correct. So how do you decide who is right - the committee that manufactures nothing - or those of us trying compete in the market place?


Again, read the ROP's, they have had valid resaons for all of the changes, all changes are voted on, I dont agree with all of them but the points made are valid.

Get involved, submit proposed changes, your input would be valuable. But the key is the format of your proposals, I have seen good proposals not make it because they were not submitted properly.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Dec 09, 2008 10:02 am 
Offline
Arc Level

Joined: Thu Jan 10, 2008 8:49 pm
Posts: 480
Location: New England
Zog,
This is why YOU should be cynical. Good proposals not accepted because they were submitted wrong? What is NFPA a bunch of lawyers? They should go for content and substance, and not worry so much about exact conformance to the rules of submission. You say that our present industrial situation is not their fault - well yes - they are not 100% to blame - but they are a contributing factor. NFPA is concerned with making money - safety is the product they sell - that premise alone is not helpful to industry. You want me to participate in their rule making and provide my comments - but if I make a mistake in the submission they throw them out!

I really don't want to come off sounding like a renegade. I do work very safely with my men and have not had an accident in over 20 years, including doing a lot of medium and high voltage work. On anything remotely dangerous I spend time to put together a 50 to 100 point checklist that we follow to the letter. We have pre-job meetings to discuss each others tasks and the relationships we share. We finish with a post meeting. Its a good method and it works.

What NFPA is doing is dumbing down the profession to the point that morons can work it. Trying to talk against the NFPA is like trying to talk against motherhood and apple pie. How can a person not be in favor of supporting every safety rule no matter how restrictive. If it saves one life then it is worth it. Unfortunately we have to live in the real world where we accept that people are fragile. I have a family member that died in a car wreck caused by a drunken driver. He would be alive today if we can ban automobiles and intoxicating liquor. Of course, we can't go back to riding horses because they also have caused several deaths and injuries. So we walk, and sit at home and wait for our government check to arrive.

OSHA can not pass laws unless the injuries they are trying to prevent effect a certain percentage of the working population. I want to say that number is 4000 injuries/year but I am not sure about the exact number. They do this because they know that the only way to prevent every accident is to remove all people from the equation. There is just too high a cost burden to industry for the entire country to invest to save the one accident. Is that ideal? No. Is it Utopia? No. But it is reality and it works to solve the common and serious problems.

Does NFPA take on a similiar approach to OSHA - I don't think so. There is no limit to how far down they can reach. Are there really going to be a large number of electricians in the hospital because they changed a 120V troffer ballast in a tee shirt that was 20% polyester?

What NFPA could and should have done was limit the PPE requirement to just those circumstances where real harm was possible to a statistical representation of electricians. But I don't see this approach - I see an approach that says all live electricity is bad. Its like Sarah Brady and gun control - there is no excuse for anyone to every own a gun! Except the government - they can do as they please.

I have electricians, that I trust with years of experience, pleading with me to remove their Level 2 coveralls because they have to work on a de-energized MCC bucket for several hours changing components. NFPA says because they are within 12 inches of the line side of the disconnect they have to be in the PPE. This is NOT a dangerour situation for them, no even close to being dangerous. NFPA has made it more dangerous by forcing the guy to sweat to death and overheat. But do you really thing the NFPA committee members can relate to that task in specific details because they have been in that situation themselves. They sure don't act like they have been there.

You sound like a person who has some insight or even connection to NFPA. Can I ask if you are trying to change them and trying to get them to be more representative of the manufacturing owners and less influenced by the vendors. I can and will defend the Salvation Army, as I believe them when they say they run their organization to help the unfortunate. I also think that NFPA has done a great job in a lot of areas that needed work, like fire system design and hazardous area classifications. But there comes a time when a goal is accomplished and continuing to develope a theme which no longer needs further developement is only distructive. We have reached it on many products in our society. I don't know how many of you use AutoCad, but Autocad 2008 is a nightmare compare to 2006. But Autodesk needs something to sell to say in business. You can just see the future of Art 130. NFPA will take this to Kevlar suits with full Scott Air paks.

My only real concern is that more people are not critical of NFPA and the influence and damage they are doing to manufacturing. I ask you, do you, in your heart, believe they the NFPA is doing it for the sake of that one burn victim they save - or because that is how the money continues to flow.

I don't want to make this personal or to be preaching from a platform.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Dec 09, 2008 11:08 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
haze10 wrote:
Zog,
This is why YOU should be cynical. Good proposals not accepted because they were submitted wrong?


There were nearly 1000 proposals last revision, they need to be in the right format to make sense of them, I can see thier point, dont want some chicken scratches on a bar napkin mailed to the NFPA office, ther needs to be a process.

haze10 wrote:
What is NFPA a bunch of lawyers?


Just 1 of them.


haze10 wrote:
You say that our present industrial situation is not their fault - well yes - they are not 100% to blame - but they are a contributing factor.


Agreed

haze10 wrote:
I do work very safely with my men


I belive you 100%, lots of people think they are safe and know the proper actions to take and really dont know squat, you are not one of those, I would be happy to have you as the safety guy in my plant anytime.

haze10 wrote:
What NFPA is doing is dumbing down the profession to the point that morons can work it.


Out of pure necessity, very few have the knowledge you do.


haze10 wrote:
Trying to talk against the NFPA is like trying to talk against motherhood and apple pie. How can a person not be in favor of supporting every safety rule no matter how restrictive. If it saves one life then it is worth it. Unfortunately we have to live in the real world where we accept that people are fragile. I have a family member that died in a car wreck caused by a drunken driver. He would be alive today if we can ban automobiles and intoxicating liquor.


No, we have strict laws against drunk driving and they are enforced as much as possible, dosent stop everyone from doing it, there are still those that dont care about themselves or others and some that just dont know any better, just like electrical safety.



haze10 wrote:
OSHA can not pass laws unless the injuries they are trying to prevent effect a certain percentage of the working population. I want to say that number is 4000 injuries/year but I am not sure about the exact number. They do this because they know that the only way to prevent every accident is to remove all people from the equation. There is just too high a cost burden to industry for the entire country to invest to save the one accident.


Saves more than that, and if that one person was someone you loved you would think differently. When the OSHA final rule came out in the mid 90's (Covering shock protection for the most part) there were around 1,200 electrical contact fatalities to electrical workers each year, now there is around 400 per year, tell me that dosent make a difference to those 800 families. Around 2,000 arc flash victims are sent to burn centers each year, I would love to see that at 0 but it never will be, but 1,000 is better than 2,000.

haze10 wrote:
Does NFPA take on a similiar approach to OSHA - I don't think so. There is no limit to how far down they can reach. Are there really going to be a large number of electricians in the hospital because they changed a 120V troffer ballast in a tee shirt that was 20% polyester?


Actually changing balasts is the #1 cause for fatal shocks in the workplace, cant find the exact # but I think it was around 450 in 2006.


haze10 wrote:
I have electricians, that I trust with years of experience, pleading with me to remove their Level 2 coveralls because they have to work on a de-energized MCC bucket for several hours changing components. NFPA says because they are within 12 inches of the line side of the disconnect they have to be in the PPE. This is NOT a dangerour situation for them, no even close to being dangerous. NFPA has made it more dangerous by forcing the guy to sweat to death and overheat.


I agree with you, but I think this requirement will lead the manufactures to design equipment with this in mind, wait, they already are. Seatbelts and airbags make the car cost more, nut worth it in the end.


haze10 wrote:
I ask you, do you, in your heart, believe they the NFPA is doing it for the sake of that one burn victim they save - or because that is how the money continues to flow.


I dont think they make any money (Not much anyways), and it will be much more than 1 burn victim, go visit a burn unit and you will chage your mind.


You are a rare thing, you have a very good knowledge of safety and power systems and probally dont need the NFPA 70E to keep your employees safe, but I have been in hundreds of large industrial plants and can tell you that 95% are deathtraps that need these rules to protect thier emplyees, I have seen some very scary stuff.

Get involved Use your views and knowledge to protect US manufacturing plants while keeping employees safe, you would be an assett to the commitee, as you are to this forum.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Dec 09, 2008 6:52 pm 
Offline
Arc Level

Joined: Thu Jan 10, 2008 8:49 pm
Posts: 480
Location: New England
Thanks Zog, I will consider all you say.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Dec 31, 2008 2:49 pm 
Offline
Sparks Level

Joined: Thu Oct 18, 2007 7:10 pm
Posts: 250
Location: NW USA
Zog wrote:
There were nearly 1000 proposals last revision, they need to be in the right format to make sense of them, I can see thier point, dont want some chicken scratches on a bar napkin mailed to the NFPA office, ther needs to be a process.

You are exaggerating to make your point. I think Haze was RIGHT ON and you're disrespecting his valid contributions by calling non-conforming submissions "chicken scratches on bar napkins". The fact is, as a professional I make it my job to understand the customers' communication in THEIR chosen protocol. If one of my customers chose to supply information on napkin notes, I would be appreciative of the information.

Zog wrote:
Just 1 of them.

That kind of a response is evidence of ignoring the forest for the trees. Haze made a valid comment about overbearing legalistic requirements and you discount that with a literal count of lawyers. My opinion is that much of the difference in this forum thread is the different perspective of individual details vs. overall context.


Zog wrote:
No, we have strict laws against drunk driving and they are enforced as much as possible, dosent stop everyone from doing it, there are still those that dont care about themselves or others and some that just dont know any better, just like electrical safety.

It is well known that the HUGE majority of drunk driving accidents are caused by repeat offenders with blood alchohol several times above most state legal limits. Yet lawmakers continue to reduce legal limits with the only effect of making families returning from weddings violators of the law. How many lives were really saved reducing legal blood alchohol allowances from .10 to .08? (many fewer than if the perpetrators with .2 or .3 could be kept off the streets).


Zog wrote:
Saves more than that, and if that one person was someone you loved you would think differently. When the OSHA final rule came out in the mid 90's (Covering shock protection for the most part) there were around 1,200 electrical contact fatalities to electrical workers each year, now there is around 400 per year, tell me that dosent make a difference to those 800 families. Around 2,000 arc flash victims are sent to burn centers each year, I would love to see that at 0 but it never will be, but 1,000 is better than 2,000.

Don't give the RULES too much credit. Safe work has more to do with education and understanding than following rules. To the extent that NFPA materials have helped educate the work force, that has been a valid contribution. There are examples in society where putting rules in place has caused workmanship to be lowered to the new standard.


Zog wrote:
Actually changing balasts is the #1 cause for fatal shocks in the workplace, cant find the exact # but I think it was around 450 in 2006

The discussion is about arc flash hazard, not electrocution.


Zog wrote:
I agree with you, but I think this requirement will lead the manufactures to design equipment with this in mind, wait, they already are. Seatbelts and airbags make the car cost more, nut worth it in the end.

And blind faith in seatbelts or airbags is much of what is wrong with today's drivers.


Zog wrote:
I dont think they make any money (Not much anyways), and it will be much more than 1 burn victim, go visit a burn unit and you will chage your mind.

This is exactly the kind of motherhood and apple pie threat/statement that Haze correctly identifies earlier. Of course nobody wants to see a burn victim, how noble of you to state that. But if preventing one burn victim causes 100 other industrial accidents because of too much cumbersome PPE or other phenomena do we still proceed?


Zog wrote:
You are a rare thing, you have a very good knowledge of safety and power systems and probally dont need the NFPA 70E to keep your employees safe, but I have been in hundreds of large industrial plants and can tell you that 95% are deathtraps that need these rules to protect thier emplyees, I have seen some very scary stuff.

I have not been in "hundreds of large industrial plants" but of the several dozen I have worked at, I have yet to find one employee or manager willing to knowingly take safety shortcuts. I think you are exagerating.

Zog wrote:
Get involved. Use your views and knowledge to protect US manufacturing plants while keeping employees safe, you would be an assett to the commitee, as you are to this forum.

This forum is a method of involvement, that could be a valuable asset to any committee member seeking feedback. But I think the point remains germaine, arbitrary rules without practical solutions, raised only on american plants put our industry at a disadvantage.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
cron
© 2017 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883