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 Post subject: FR PPE with doors closed
PostPosted: Wed Aug 25, 2010 2:23 pm 
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We have transfer switches that are labeled above category 4. We stand in front of them and operate them each month with the push buttons on the door. Are we required to wear any PPE.


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PostPosted: Thu Aug 26, 2010 5:48 am 
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crog333 wrote:
We have transfer switches that are labeled above category 4. We stand in front of them and operate them each month with the push buttons on the door. Are we required to wear any PPE.


Unless the enclosures are arc rated that is an interaction and requires the operator to wear the proper PPE, but your are >40 cal/cm2 so you need to either operate the switches remptely or mitigate the arc flash hazard level.


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PostPosted: Thu Aug 26, 2010 3:07 pm 
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Interaction Requres PPE

Zog:
Where is it in writing that interaction with doors closed constitute the same PPE requirements as exposed energized?

crog333


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PostPosted: Fri Aug 27, 2010 6:03 am 
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crog333 wrote:
Zog:
Where is it in writing that interaction with doors closed constitute the same PPE requirements as exposed energized?

crog333


Artile 100, the definition of "Arc flash hazard". And operating a switch or breaker with the doors closed is specifically listed in the tables.

There are no calculations for "doors closed" and unless it is arc rated switchgear the enclosure likely will not contain the arc flash, so PPE is required.


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PostPosted: Fri Aug 27, 2010 6:26 am 
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What if the worker is simply right next to the equipment while it’s being automatically or remote operated (e.g. janitor sweeping the floor next to an MCC)? In an industrial setting there’re hundreds of contactors, breakers, transfer switches, MCCs and other power delivery equipment that are typically operated from a control room or by a computer system all day long while workers perform other tasks near the equipment or move around the equipment. IMO…while the equipment may not be “arc-rated” I believe the equipment integrity and the fact it’s being operated as designed must be taken into account for something.


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PostPosted: Fri Aug 27, 2010 7:31 am 
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SCGEng1 wrote:
What if the worker is simply right next to the equipment while it’s being automatically or remote operated (e.g. janitor sweeping the floor next to an MCC)? In an industrial setting there’re hundreds of contactors, breakers, transfer switches, MCCs and other power delivery equipment that are typically operated from a control room or by a computer system all day long while workers perform other tasks near the equipment or move around the equipment. IMO…while the equipment may not be “arc-rated” I believe the equipment integrity and the fact it’s being operated as designed must be taken into account for something.


Funny you mentioned that, a friend of mone had one of his techs burned earlier this year, he was just walking past an MCC on his way back from lunch when the contactor energized it flashed, blew open the door, and gave him 2nd degree burns.

But, not allowing people to walk past stuff in a plant is not reasonable and nothing in 70E requires waering PPE to walk past an MCC, but it can happen.

Normal switchgear has nothing in the design specs that says it must contain an arc flash, in fact I see the aftermath of enclosure failures every week. It may or may not contain the arc, new gear in good condition with all the retaining hardware in place stands a better chance than real life gear. The majority of the gear I see in plants are missing hardware or they are all loose besides one bolt for the door (People just being lazy). Some gear from the 60's and 70's has vents on the doors for the breakers, how do you adress that?

IMO there are too many variables on the design and condition of the equipment in use out there for the 70E group to feel it is safe, so they error on the safe side.


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PostPosted: Fri Aug 27, 2010 11:35 am 
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crog333 wrote:
Zog:
Where is it in writing that interaction with doors closed constitute the same PPE requirements as exposed energized?

crog333


Article 130.7(C) says that when an employee is working in the Arc Flash Boundary they shall wear protective clothing and other PPE based on either the incident energy analysis or the hazard/risk categories providing the maximum short circuit current capacity and fault clearing times specified in the T130.7(C)(9) notes are not exceeded.

So when is one considered working in the arc flash protection boundary? According to the 2004 edition of 70E the definition of the flash protection boundary was "an approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur". However, the 2009 70E definition now reads, "when an arc flash hazard exists, an approach limit at a distance from a perspective arc source within which a person could receive a second degree burn if an electrical arc flash were to occur.

In article 100 of the '09 70E under the definition of arc flash hazard in FPN No. 1 the standard states, "an arc flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such manner that could cause an electric arc. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard". FPN No. 2 references you to T130.7(C)(9) for examples of activities that could pose an AF hazard.

See question #2 in [url="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973"]OSHA letter of interpretation[/url].


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PostPosted: Mon Aug 30, 2010 12:09 am 
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We have transfer switches similar in design and monthly testing. We are a little above 40 cal/cm². Most likely we will use a device to extend our reach so that we can push the button, etc. below the 40 cal level in our 40 cal PPE. Hopefully once everyone is onboard we can install a set of remote buttons for this function that reside outside of the arc flash boundary.


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PostPosted: Mon Aug 30, 2010 7:03 am 
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Data Center Electrician wrote:
We have transfer switches similar in design and monthly testing. We are a little above 40 cal/cm². Most likely we will use a device to extend our reach so that we can push the button, etc. below the 40 cal level in our 40 cal PPE. Hopefully once everyone is onboard we can install a set of remote buttons for this function that reside outside of the arc flash boundary.


There are wireless remote operators available that would allow you to do this outside the AFB. No modifactions required to the equipment.


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PostPosted: Wed Jul 13, 2011 10:19 am 
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A King wrote:
. . . the 2009 70E definition now reads, "when an arc flash hazard exists, an approach limit at a distance from a perspective arc source within which a person could receive a second degree burn if an electrical arc flash were to occur.


Do we say that the distance used when the door is closed does not change from the distance calculated in a normal 70e engineering study? (Trying to confirm my understanding)

How are others handling 480V disconnects on equipment that operators lock out on a regular basis to do machine cleaning, change-overs, etc.?

This topic is interesting to me as I have talked with engineers doing 70e studies as well as safety trainers teaching 70e and they all look at me like I am crazy when I ask about PPE with the doors closed being the same as with the cabinet open.

Thanks!


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PostPosted: Thu Jul 14, 2011 5:03 am 
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The risk obviously has to be less with doors closed. For one, you are further away from the source as you are now interacting with the door face rather than interior components. Second, you have a secure metal barrier between you and the source.

You need to do some searches as this has been discussed in detail.
There are those of us who believe Art 130 does NOT to apply to 'dead front' routine operation of electrical equipment maintained in a working condition. Art 130 provides reference to this, as well as reduced risk with doors closed.


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PostPosted: Thu Jul 14, 2011 8:29 am 
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The equipment our operators are expected to lockout is all HRC 0. If there are no exposed energized conductors or circuit components operators just need to be properly trained per OSHA 1910.147 in order to be authorized to perform lockout for servicing and maintenance. An electrician opening this electrical panel however must have additional training and wear HRC 0 PPE.

Areas with higher incident energy such as at the bus, the service, pad mounted transformers and capacitor banks are only accessed by qualified electrical workers who are required to wear the appropriate arc flash PPE when exposed to those hazards. We require arc flash PPE for operating fused switches or breakers located on the service even with all covers securely in place and no exposed electrical parts due to the high IE and the fact the equipment is not designed to contain an arc flash event.

Not everything in the standard is black and white and there is some interpretation required. In almost the same breath the standard says, “An arc flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such manner that could cause an electric arc.” However the very next sentence says, “Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard.”

You have to do a hazard analysis and look for ways to mitigate exposure but probability and severity of injury also get considered. Article 130.3(A) states that, “In those cases where detailed arc flash hazard analysis calculations are not performed for systems that are between 50-600V, the arc flash protection boundary shall be 4 ft...” So, if your analysis didn’t include the 277V light switch in the office or plugging a laptop into a 120V receptacle, is there a 4 ft. arc flash boundary and HRC 0 PPE required for these interactions? I think not, but where in the standard is that line drawn?

There is nothing specified in the standard to allow reducing the arc flash boundary from your calculated distance for operation with doors closed. T130.7(C)(9) does indicate credit given to operation with covers on though. That’s why I think you have to apply some common sense and have a written electrical safety program documenting your company policy.


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PostPosted: Tue Jul 19, 2011 3:07 pm 
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Zog wrote:
There are wireless remote operators available that would allow you to do this outside the AFB. No modifactions required to the equipment.


For switching equipments such as RMU, remote switching is always preferred because of the higher incident energy and also the chances of someone switching it directly to ground.

A King wrote:
Article 130.7(C) says that when an employee is working in the Arc Flash Boundary they shall wear protective clothing and other PPE based on either the incident energy analysis or the hazard/risk categories providing the maximum short circuit current capacity and fault clearing times specified in the T130.7(C)(9) notes are not exceeded.

So when is one considered working in the arc flash protection boundary? According to the 2004 edition of 70E the definition of the flash protection boundary was "an approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur". However, the 2009 70E definition now reads, "when an arc flash hazard exists, an approach limit at a distance from a perspective arc source within which a person could receive a second degree burn if an electrical arc flash were to occur.

In article 100 of the '09 70E under the definition of arc flash hazard in FPN No. 1 the standard states, "an arc flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such manner that could cause an electric arc. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard". FPN No. 2 references you to T130.7(C)(9) for examples of activities that could pose an AF hazard.

See question #2 in [url="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973"]OSHA letter of interpretation[/url].


I agree to what is written but if the MCC or starter cell are rated to contain an arc fault, this should over write what is in the standard.

However, unless you know the MCC you got is rated for arc fault contained, please check with the manufacturer.

Because this is a manufactured enclosure, my understanding is it should be consider a permanent rating unless proven otherwise (meaning you cannot make any physical changes to the enclosure). Think of it as an DIP rated enclosure (same concept). The enclosure is type tested and shall not be modified in any manner because it can affect the structurally integrity of the enclosure.

To say that a missing bolt caused an arc to blow open an arc contained cell is possible but it should be the responsibility of the company to ensure routine checks are in place and operators have good work practice/worksmenship.

fangle1948 wrote:
Do we say that the distance used when the door is closed does not change from the distance calculated in a normal 70e engineering study? (Trying to confirm my understanding)

How are others handling 480V disconnects on equipment that operators lock out on a regular basis to do machine cleaning, change-overs, etc.?

This topic is interesting to me as I have talked with engineers doing 70e studies as well as safety trainers teaching 70e and they all look at me like I am crazy when I ask about PPE with the doors closed being the same as with the cabinet open.

Thanks!


You need to be more precise with what you mean by (e.g. where is this taking place? In the MCC or in the field?)

"480V disconnects on equipment that operators lock out on a regular basis to do machine cleaning, change-overs, etc.?".

Those actions which you have stated requires the upstream breaker to be open when conducting the work. Appropriate PPE shall be worn at the time of isolation (unless enclosure is arc fault contain rated) and testing for dead. Once the equipment is proven to be dead, PPE can then be removed.

Unless manufacturer confirm the enclosure is rated for arc fault contain, you should apply the boundary requirement.


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PostPosted: Sun Jul 31, 2011 5:14 pm 
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Strudel wrote:
You need to be more precise with what you mean by (e.g. where is this taking place? In the MCC or in the field?)

"480V disconnects on equipment that operators lock out on a regular basis to do machine cleaning, change-overs, etc.?".

Those actions which you have stated requires the upstream breaker to be open when conducting the work. Appropriate PPE shall be worn at the time of isolation (unless enclosure is arc fault contain rated) and testing for dead. Once the equipment is proven to be dead, PPE can then be removed.

Unless manufacturer confirm the enclosure is rated for arc fault contain, you should apply the boundary requirement.



Sorry I was not clear. I'm asking about a piece of manufacturing equipment that requires cleaning externally, not inside the electrical enclosure. The operators would LOTO the electrical disconnect, air supply, etc. so that the machine could not move - this is done at the machine itself, where the control panel has a 480V main disconnect integrated into the front panel. This is the same panel that has the pushbuttons, etc. used to operate the machine. They would not open any electrical cabinets when doing this cleaning. If they would need to follow 70e procedures when locking out 480V power it would mean a large change for the skills required to be a machine operator. Our maintenance staff are the only people opening or entering the electrical enclosures (energized or not) and they do have 70e training and equipment.


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PostPosted: Mon Aug 01, 2011 6:30 am 
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fangle,
You have to decide this on your own as there are two competing opinions. One is that is Arc Flash does not apply to deadfront lockouts, the other is that it does. If you search you will find more code references and opinions. My opinion is that as long as the equipment is maintained in good condition, LOTO for an equipment like this would not require Arc Flash. But others will disagree.


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PostPosted: Mon Aug 01, 2011 9:15 am 
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haze10 wrote:
fangle,
You have to decide this on your own as there are two competing opinions. One is that is Arc Flash does not apply to deadfront lockouts, the other is that it does. If you search you will find more code references and opinions. My opinion is that as long as the equipment is maintained in good condition, LOTO for an equipment like this would not require Arc Flash. But others will disagree.

I agree, but what do you put on the label at the disconnect? If you calculate an IE of 10, do you put IE = 10 or Cat 3, with the Electrical Safety Procedures saying that PPE is not required for operation of the disconnect with the doors closed? Or do you put Cat 0 and have the Electrical Safety Procedures say that opening the door is prohibited while energized? Seems like you still need an IE=10 label to show what PPE to test voltagee if the door is opened.


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PostPosted: Wed Aug 03, 2011 5:14 am 
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We always put the calculated incident energy on the door, and then by procedure allow for reduced PPE (HRC 0) when the door is closed with all latches in tact and secured. This is done for LOTO only, not resetting a breaker after a trip.


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PostPosted: Mon Aug 08, 2011 6:27 am 
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I would be one of those that look at you crossed eyed if you say that doors closed requires the same ppe as doors open. But for some reason, members on this board think otherwise. Did you see this question of the week?

http://arcflashforum.com/showthread.php?t=1617


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PostPosted: Mon Aug 08, 2011 8:25 am 
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We still struggle with this too. 70E seems to talk all around the "interaction" issue. No problem if it's in good condtion, maintained etc.... but...

Apply the door/interaction logic to driving and we should all drive very slow in case we lose the steering. At what point are there too many "what if's"? Safety is huge but in the summer, so is heat stroke.


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PostPosted: Mon Aug 08, 2011 10:21 am 
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The confusion stems from the false belief that switchgear is designed or tested to contain an arc, which it is not unless it is specifically "arc rated" per ANSI standards.


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