Operating a Breaker

What are you recommending your customer when they ask you regarding recommendation on PPE for operating a circuit breaker with covers on.

1. 480V Switchboard / Switchgear

2. 208V UL Panel / Explosion proof panel

3. 480, 208V Disconnects.

An arc-flash study is performed and we are asked regarding whether they have to wear PPE for operating the above equipment.

Need thoughts.

Yes they do, unless the switchgear is arc rated. That why many companies are doing remote switching and racking

www.remoterackingsolutions.com

On the switchgear I would say yes.

On anything that is explosion proof, Class I or II Div 1, then no. The equipment is inherently arc proof and tested to vent any deflagration inside and vent the gas below the auto-ignition of the Class its in. It is not listed as Arc Fault, but if you understand the test requirements to get a listing then you know it can't release a flame.

On circuit breaker panels I think you get a mix of results. Some say that AF is only for exposed live parts, and with 2009 switched high energy change of states like switchgear. I am not sure molded case would fall in the same category. If it is under 240V and fed from less than 125KVA xfrm, then an analysis is not required. The PPE level is not specified, so if you chose -1, tee shirt and jeans, you would be fine. This would also conform to the NFPA table for under 10KA fault current.

Some of these questions are controversial. To say PPE is required to operate a breaker on dead front equipment is to say the manufacturer's equipment is not going to stand the rigors of duty it was designed for. I don't think Cutler Hammer or GE will remain quiet indefinitly about that, though at this point I am not aware of any statements they have made.

Containment of an arc flash was never part of the design, thats why there are new standards for switchgear to be "arc rated"

It is a reasonable assumption that "Arc Rated" equipment will help protect personnel, however, to simplify personnel protection to a "yes-no" answer based on equipment designation is dangerous and negligent, overlooking where arc venting is directed or whether the equipment is operated within it's parameters. And yes-no answers based only on equipment designation, do not include probability and consequences that are recognized in NFPA 70E prescriptive tables. Finally, PPE required by NFPA 70E is thermal rated yet arc rated gear has much to do with ballistic type control, to assume protection for one phenomena based on coincidental design for the other is not good science though it might be the best we have.

I stand by my statement that this is controversial.

I expect there will be further interpretations from the manufacturers of non arc rated equipment in the future, because it would be a liability to sell apparatus that requires thermal protection to operate in the fashion intended.

You can say that again. But, you still need PPE for operating switchgear, I have seen dozens of cases when the switchgear failed to contain a fault, ,my point was the manufactures never designed it to contain a fault in the past.

I do not believe it is a requirement to wear PPE to operate some of the equipment listed in the original question. With further analysis one can determine that some non arc rated switchgear may safely be operated according to NFPA 70E without PPE.

It sounds like you are selling something

The assumption that the doors will come open has to be made, there is no way (As of now) to calulate the hazards with the doors closed. Too many assumptions of the condition of the switchgear and retention hardware would need to be made.

Just safety my friend, I have had some personal experiences with burn units that I dont wish on my worst enemy.

Hi,

NFPA 70E 2004 was not clear on this point.

NFPA 70E 2009 130.7(C)(9) FPN No1 clarifies this: "The collective experience of the task group is that in most cases closed doors do not provide enough protection to eliminate the need for PPE..."

It's now hard to say anything else to a customer asking that question.

Also, Table 130.7(C)(9) now gives hazard category for operating equipment with covers on or off.

For example, racking in or out a CB from a 600 V swgr with doors open or closed is category 4...

Simply operating LV D.S. or CB with doors closed is category 0.

If the equipment is within the limitations of the tables.

Correct me where I go astray.

I thought that reference was not specific to "switchgear" but something like high energy change of state. This would of course be switchgear, but why is it not a Size 4 motor starter, or a 2, or even a 0. Where do you draw the line.

NFPA 70E does provide a flowchart which you can use to help Annx F.1.
There are no calculations for operating a circuit breaker in a panel with covers on. Therefore I do not believe you will see in the text of 70E sny suggestion to do so. Some places figure the door is open for the PPE requirements, I think that is a little exteme, I would rather is that a minimum of cotton clothing and leather gloves be used. But, for larger gear because fault currents and the shape of the cubicles I would require a Arc Rated faceshield, FR clothing and Heavy leather gloves.

The more important question is the enclosure rated to withstand? Which is a tough question, sometimes, to answer.

One would hope that if it came form a UL panel shop and was listed it would be, but field modifications or custom on site fabricated (they do exist) enclosures may not be able to contain the flash/blast.

It is always safer to err on the more stringent side.

There is nothing in any manufacturing standard that requires the switchgear to contain an arc flash, no one ever made that promise and if you read the inst book from any OEM's swgr you will see the warnings and disclaimers about this all over it.

Now new arc rated switchgear, tested and rated per the new ANSI arc rated switchgear standard is a different story, but besides some of the testing I have witnessed, I have yet to see any of this new gear in place, it is very expensive and not many companies are willing to make the inverstment, buying a flash suit for thier guys is cheaper.

Page 8
http://ecatalog.squared.com/pubs/El...r, Metal Clad/Masterclad Series 5/6055-30.pdf

do not open doors unless breaker is tripped....

Page 26

When the switchgear is energized....door closed

Page 27....

And yes their is arc resistant gear
http://ecatalog.squared.com/pubs/El... Metal Clad/Masterclad Series 5/C_6055-46.pdf

I may not have been clear in my wording...But I would hope that if the tag on the gear said XYZ AIC that the enclosure should be able to withstand XYZ AIC, it may never function again but it should be able to contain the blast and not cause damage to the surrounding. Note I did not say person.

Bottom line nothing can contain a catastrophic failure, hence the term catastrophic.

AIC rating has nothing to do witth the switchgear containing the pressures from an arc flash, it is a short circuit interuption rating, you are comparing apples and oranges.

My company designs and builds switchgear, and I can tell you unless it is of the Arc-Resistant type and qualified in accordance with ANSI/IEEE C37.20.7 no switchgear will contain an arc flash.

This is a very dangerous assumption many people make, thats why arc flash PPE is required for switchgear operations with the doors closed in the 70E tables.

You are correct...

I never said one should not wear the proper PPE...Though one should also always have the doors closed, however this does pose a problem for racking breakers.

You said the gear should contain the blast, which it probally wont. As far as racking breakers go, thats what remote racking is for. www.remoterackingsolutions.com

I shall be more carefull with my wording...

Though to an extent it will contain the blast, haha, not that it will be functional again.

Points of weakness would be the door hinges and latching mechanisms, causing the door to fly off. I would think.