Arc Flash Results

I have finished calculating results and I am now working on analyzing and presenting my results to clients. Should I come up with a 'category per task' list like Table 130.7 (C) (9) (a) and adapt it to my calculations? For example with switchgear, I assume that reading a meter and operating equipment when doors are closed requires a lower hazard/risk category than any type of work when doors are open. If so, there should be a list similar to Table 130.7 (C) (9) (a) that I will provide. Should a copy be placed outside the fence of a substation too? How does this all relate to the labels to be placed on the equipment?

I know this should partly depend on what the client wants, but I am not sure if they even know what they want or need. Just trying to get a feel for what others do.

You either use the tables or you do an analysis, you cant mix the 2, they are based on different assumptions.

Is this your 1st arc flash study for a client? What software did you use?

I used PTW32. And Yes this is my first with the client.

I was assuming that no matter what my calculated IE or boundary might be for working on a circuit breaker, I could read the relay's meter or settings assuming a category 0, as long as the hinged/bolted door is closed. Is this not correct? If correct, wouldn't this 'open the door' for a list of tasks. Maybe not exactly like the Table, but along the same lines.

Unless the switchgear is arc rated, there is still a hazard and you are setting yourself up for trouble by putting multiple labels, plus it confuses the workers. Stick with one Ei foor each piece of equipment, in most cases the highest.

Keep in mind that the 70E tables tasks are based on different assumed working distances, among other assumptions. (risks)

I would discuss that with the client, that those tasks can be done, but dont put it in your report.

Wasn't planning on using more than one label. Just talking about performing a specific task that doesn't seem to require, in this case, Category 4 PPE -- a task such as reading a meter or checking settings on an electronic relay.

Arc Flash PPE is only required when working on, or near, exposed energized components. If you have a metal deadfront, then no PPE is required. So reading meters is a non-event. The confusion comes to play because we have two methods to conform, one being the analysis method which you did, and the other being the PPE/Task Matrix. The Task Matrix calls for specific PPE levels for work that is NOT on, or near, exposed parts, like reading meters or operating MCC buckets with deadfront. I have no idea of why they did this and wish that they hadn't. But like most executives who have to make decision without experience, I guess they just wanted to be 'ultra safe'. But it creates problems in the field for those small businesses that only want to, and can, follow the task matrix for their electricians. That means that regular operators have to be in Level -1 or Level 0 to throw a disconnect on a deadfront MCC. Its a problem because almost all clothing and especially uniforms today are a polyblend.

And how many members of the 70E commitee do you know? I know for a fact that nearly every one of them (Besides the specialsits) have waaaay more real life hands on experience than you could imagine.

I am appaled that you claim to do consulting and dont even know the basis of the tables or spent any time with any of the commitee.

And, unless the switchgear is arc rated switchgear, you are wrong, please post your reference to where this is acceptable.

BTW, how much arc flash testing of metal clad switchgear have you witnessed? You willing to bet peoples unburned flesh on your assumptions?

Nfpa 70e

The arc flash protection boundary is defined in part "at a distance from Exposed live parts"....etc......Exposed is defined in part as "capable of being inadvertently touched"....(for below 600 volts that is).

It is pretty hard for me to understand how we can be exposed to live parts on the outside of a closed switchgear door.

Neither do I know any committee members personally, but do believe that I am qualified by education and 31 years of hands on experience to do my job and discuss the pros and cons of arc flash with others. I do not need to completely understand the origin of the tables. I do need to be able to properly interpret any of the standards that I work with and apply these standards to real world practices based on my education and experience. When I have questions or ideas, then I come to a forum like this one to post concerns and questions in hopes of getting the input from another qualified colleague, or occasionally help someone else with a problem.

Oh and yes I have experienced the destruction of switchgear, standalone breakers, and voltage regulators from internal failures on many occasions.

That's my two cents worth.
Alan

Well, questioning the experience levels of the commitee members (Some of whom are friends) really rubbed me the wrong way (Obviously). The 70E handbook discusses the basis of the tables and should be required reading for anyone doing raining or consulting on 70E complaiance. The appliaction of the arc flash boundary is misrepresented in the 2004 70E and is being revised in 2009 to discuss "interaction" with energized equipment because the live parts do not need be exposed to present an arc flash hazard.

Take this racking accident for example, no exposed live parts here
http://www.liveleak.com/view?i=995_1213752982

This is exactly what I am talking about. The video you show is with an electrician with the doors open, inserting or racking, yeh and I guess with shutters there is no live parts exposed but that pushing the point. Of course this is a dangerous operation and requires PPE.
But if the doors were closed, you would require a person who is merely walking by the switchgear in front of it to be in PPE? Whats the difference between walking by, and pausing for 3 seconds to read a meter.

Can I read the Table? Yes, I can read. Do I know any board members, no, but that doesn't change the fact that their 'conclusions' are creating difficulties in the work place where none existed before. Point in case and an example of reading the Table.

The Janitor needs to turn off the hallway lights at the end of the day. They are supplied from a switch rated breaker in the 120/208 panel, a QO single pole 20A. The panel is less than 10K Isc which would be typical.
Reading the Table below:

Table 130.7(C)(9)(A) Hazard/Risk Category Classifications "Task (Live Equipment; Work Within Flash Protection Boundary)" "Hazard/Risk
Category"
Panelboards Rated 240V and Below [1] [3]
Circuit Breaker (CB) or fused switch operation with covers on "0" N N

So according to the Table it would be Level 0 without the need for VR gloves or tools. Note 1 applies because we are less than 10K Isc. So we reduce one PPE level to Level -1.

Table 130.7(C)(11) Protective Clothing Characteristics for Typical Protective Clothing Systems
Hazard/Risk Category Clothing Description # Layers Minimum ATPV or EBT Rating of PPE (cal/cm2)
-1 Non-melting, flammable materials, wt: 4.5oz/yd2 1 N/A

-1 is an all cotton short sleeve T shirt of 4.6 oz/yd and dungaree or all cotton pants.

But guess what. The Janitor is required to wear a company supplied uniform that is 40% polyester. This is a melting fiber and is prohibited. So according to the Table he needs to change his clothes and don the appropriate Level -1 PPE.

Same Level PPE of 0 applies for throwing a disconnect on a MCC. Only this time the reduction by one won't apply. So now we need a long sleeve all cotton shirt. Only all 100 operators have the same 40% polyester blend uniform. What do we do?

Everytime someone in management first sees this Table the first question is - you mean operators can't perform lock out/tag out anymore, or can't switch on a circuit breaker? How would you explain the Table to them?

I'm not able to quote the Bible by passage, and I can't quote NFPA70E either, but I believe the intent is to protect persons working 'on' or 'near' exposed and energized parts. WHile switchgear is typically 'energized' its not usually 'exposed'. Exposed means you have to be able to see or reach out and touch the part. Not that there is live parts behind the metal doors that are closed and we 'could' see them if we opened the doors.

Congress means well. I truly believe that every Senator and Representative truely believes that they did the right thing to the present day in the US Energy Policy. But the evidence is contrary.

Do the Good Members of the NFPA also believe that every business in the US is going to go to the Site Manager to get a live work permit because an electrician needs change a fuse in an energized MCC. Yes, I guess we can just shut the refinery down so we don't have to be 'exposed'.

I'm sorry, but there are lots of flaws in the code, and to me they examplify a lack of understand of how large manufacturing works.

And yes, my BE from an accredited US University in Electrical Engineering, my PE Registration in 3 States, my Master Electricians License in two States, and my 30 years experience in the petrochemical business may not be sufficient to fully understand the complexities of the NFPA member intents - but if not me - then who?

If the NFPA board truely expects us to be in Level 0 PPE to walk by switchgear and pause to read a meter, all I can say is - "I lost my job to China"

I would be surprised if there are any of us that did not see issues with the standards. After all they are adopted by committee and with multiple people from different backgrounds involved, I would always expect that there would be comprimises to get it done. It is through discussions like these that allow the committee folks to see the problems and incorporate appropriate changes to the codes. I absolutely believe that it is our job to question why when a person can't walk by an enclosed piece of gear without having to wear special clothing, among other issues as well.

If I were to apply this philosophy to a utility system, then the padmounted transformers in residential yards that kids play on and have picnics on would need to be fenced. I see kids playing on these things all of the time and it has always made me nervous. We put danger signs all over them and it has always made me wonder, if that is the case, then why are we putting them in peoples yards? But then I guess we probably also need fenced and gated streets so the kids would not be able to run out in front of a car as well.

Sometimes I think they end up applying the old air bag philosophy, if one is good then it must follow that 8 or 10 will be better....maybe not?

I have always recommended to my clients that they put their employees in FR clothing and these days I am recommending no less than 8 cal. for primary work. I am absolutely recommending that they do not take the "advise" from NESC 410 and just put their people in 4 cal garments for work below 1000 volts. This is one case where I believe the committee got it backwards!

I believe that we have to recognize that energized work will always have hazards associated with it, hence "reasonable" rules for protection. The committees even recognize that excessive PPE could make the job more dangerous and allow less PPE when the employer believes this to be the case.....and who among us wants to be the first to stick our neck in that noose?

I would also say that we use what we have today from the standards. While we should be aware of what may be on the horizon, we do not know what will and will not make it through the code process. And I certainly hope that the committee does not make an issue of someone being in the vicinity of closed and locked switchgear. We read meters daily in the utility field and while they are locked, they are accessible to non-qualified personnel. And some are fed directly from a 480 volt secondary with no voltage transformers.

Issues, Issues, Issues!
Alan

Risk, interaction with equipment or not interacting. Could it just blow up as someone is walking by sure, just happened to an employee of a friend of mine last month, but the line of risk needs to be drawn somewhere.

There were nearly 300 proposed changes to the tables for the 2009 rev, if you have questions or problems with the tables, submit a proposed change. The ROP for the 2009 70E is available on line, reading that may answer some questions.

He needs to be "qualified just like any other trade to operate the equipment, he may be trained on this task only.

This note is being removed from the tables, no justifiable reason for it.

Again, they need to be qualified, and meltable fabrics for operation of distrubution equipment has been banned by OSHA since 1981, nothing new here, buy them new uniforms.

Answer is, yep, they cant do that anymore without the proper training, PPE, and knowledge about the equipment.

Where does it say the site manager has to sign the permit? In the example in the annex? Just an example, can be modified as needed.

Nope not perfect, but saving lives already. Many changes to some in 2009 to make it easier to understand and more practical to implement.

Bravo, but I am sure the 70E wasnt covered in depth in any of those programs. Thats why training is needed, and there are experts (Like our host) that do nothing else but live and breathe the 70E. It takes alot of effort and commitment to fully understand the application of the 70E enough to consult companies on compliance.

OSHA has required "Level 0" for switchgear rooms for almost 30 years, nothing new there. Being in the oil industry, I think your job is safe.

I dint mean my post to be an attack, and going back and reading it I guess it sort of came off that way, for that I apoligize, however, your comment about the qualifications and experience level of the commitee rubbed me the wrong way, these guys (And gals) spend hundreds of hours per year, mostly on thier own time as volunteers to help make our workplaces safer and save lives. I have seen many burn victims (From arc flash and also my young daughter from another accident), the pain and suffering they go through is worth anything we need to sacrifice to prevent as many of these types of accidents from happening as possible.