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| Author: | PUCKMAN [ Thu Jan 14, 2010 2:58 pm ] |
| Post subject: | qualified employee |
I work at a plant where we are trying at 70e and a question came up about a employee who is not a 'qualified employee' is he able to shut off a cb in a mcc unit without opening the door and without ppe on? Can he shut off or on a cb for any reason? This is a 480 volt bucket. |
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| Author: | Zog [ Thu Jan 14, 2010 4:02 pm ] |
| Post subject: | |
PUCKMAN wrote: I work at a plant where we are trying at 70e and a question came up about a employee who is not a 'qualified employee' is he able to shut off a cb in a mcc unit without opening the door and without ppe on? Can he shut off or on a cb for any reason? This is a 480 volt bucket.
No, and neither would a qualified person, PPE is still required for operating a 480V breaker with the door closed. |
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| Author: | haze10 [ Wed Jan 20, 2010 11:50 am ] |
| Post subject: | |
This question comes up quite frequently. It is normal and typical in industrial plants, at least historically, for operators without electrical qualifications to perform 'lock out/tag out' on field equipment by transition of a breaker, MCC disconnect, or safety switch. Art 130 specifically deals with PPE protection and qualifications for performing 'live' work. Obviously, making a transition of any of the above devices, with doors closed, and panels on, is NOT live work. The 'change in opinion' about operation with doors closed, comes from 130.7(c)9 FPN No. 1: "...In several cases where the risk of an arc flash incident is considered low, very low, or extremely low by the task group, the hazard/risk category number has been reduced by 1,2, or 3 numbers, respectively. 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 for instances where the state of the equipment is known to readily change (e.g., doors open or closed, rack in or rack out). The premise used by the Task Group is considered to be reasonable, based on the consensus judgement of the full NFPA 70E Technical Committee." Almost all agree that the above statement would include Switchgear, because of the high change in energy. This would include, mere operation of switching in or out a switchgear breaker even with doors closed. The point of disagreement is how far do we take this. An office 120V wall switch is changing the state of 800 watts of fluorescent fixtures, but do we require the office worker to don PPE to turn on the lights in the office? The janitor, at the end of the day, walks to the 208/120 lighting panel and turns off all the breakers for the hall lights before he leaves, and the office manager turns them back on again when she arrives in the morning. Do they need PPE, while operating these breakers, which are designed and listed for this service, with panels on? This is usually where the point of disagreement begins. It is my opinion, at least until the next edition or technical advisory appears, that Art 130 is designed to reduce the risk of injury by protecting trained personnel while performing 'live' work. Live work means exposure to live conductors. The intent of the code was NOT to stop utilization of electrical equipment by non-qualified persons when that equipment was specifically designed and rated for such service. This permits the secretary in her poly/nylon pants suit to turn on her light switch as she enters the office. From my prospectus, which others disagree, it also permits operation of basic and customary equipment like circuit breakers, safety switches, and MCC bucket handles (with doors closed). When such equipment, begins to resemble the energy levels of switching similar to Switchgear, then I believe the limit appears. What constitutes this 'level of energy' is not specified and up to the judgment of the property owner. For an industrial site I would not limit operators from continuing to do lock outs on MCCs up to size 3 starters, maybe 4; 480 and 208 breakers to 225A. I would mention that I do not agree that any operator should touch electrical equipment without some basic and repeated training. They should be taught not to stand directly in front of the door, to stand off to the side with back to equipment and to turn away while transitioning. Lock out/tag out training usually includes this as well as means to verify that the correct disconnect was operated for the piece of equipment in question. These are my thoughts of interpretation. I have these because NFPA did not do a very good job defining the limit with a fault current value, or IE value. The argument also comes up that most MCC's, safety switches, and panel boards are NOT arc flash rated. Meaning they might 'NOT' contain an arc flash and result in moving sheet metal. This is a risk. In an industrial site I would rate this risk remote in comparison to the daily risk associated with any manufacturing site. It comes down to what is acceptable. While I have seen electrical equipment 'short' because of age or water intrusion, and arc internally, I have not seen any that blew the doors off, especially not on the low energy equipment. I am sure it happened but what is the likelihood. Do we reach the point that an office worker can not even 'walk' by the lighting panel in the hallway with PPE? I think a discussion and agreement on where that permissible limit exists would be welcomed. |
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| Author: | Terawatt [ Fri Jan 22, 2010 6:59 pm ] |
| Post subject: | |
Racking in Switchgear and MCC breakers NFPA 70E tables indicate PPE 4 for racking in breakers on 600V class MCC's and switchgear...What about PPE for racking into/out of (or measuring/confirming no voltage on supposedly 'dead') buses that are revealed to be HRC "Dangerous" by an AF Study and cannot be mitigated? An example would be the secondary of a 4160/480V delta/wye 1500kVA XFMR with no LVSWGR secondary Main but Feeder breakers that rack in/out of that HRC "Dangerous" bus. Further, this XFMR is at the end of a 5kV loop feed, all protected by a single OC relay AND the individual XFMR MVS fuse cannot be reduced in size. The MVS is HRC 2. Disconnecting the MVS affects multiple production lines (no power segregation). |
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| Author: | Zog [ Sat Jan 23, 2010 6:55 am ] |
| Post subject: | |
Terawatt wrote: NFPA 70E tables indicate PPE 4 for racking in breakers on 600V class MCC's and switchgear...What about PPE for racking into/out of (or measuring/confirming no voltage on supposedly 'dead') buses that are revealed to be HRC "Dangerous" by an AF Study and cannot be mitigated? An example would be the secondary of a 4160/480V delta/wye 1500kVA XFMR with no LVSWGR secondary Main but Feeder breakers that rack in/out of that HRC "Dangerous" bus. Further, this XFMR is at the end of a 5kV loop feed, all protected by a single OC relay AND the individual XFMR MVS fuse cannot be reduced in size. The MVS is HRC 2. Disconnecting the MVS affects multiple production lines (no power segregation).
Everything can be mitigated, but you sound like a perfect canidate for remote racking. http://www.cbsarcsafe.com/ |
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| Author: | haze10 [ Sat Jan 23, 2010 9:30 pm ] |
| Post subject: | |
You main problem here is speed. Is the HRC Dangerous based upon 2 sec clearing? I think S&C is making a MV current limiting fuse with and electronic programmer. The other options are: Secondary Main Fuse or Breaker added, increase imp% on transformer, or add line reactors, later two reduce fault current. Remote racking, switching, and voltage indication are also options. |
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| Author: | MIEngineer [ Mon Jan 25, 2010 9:23 am ] |
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Requiring PPE for office workers (even HRC 0) to switch lighting breakers is definitely an inconvenience. My look at it though is that if I am using the tables it is specifically mentioned within them. I feel as if I am following part of NFPA 70E I should follow the rest also. Todd |
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| Author: | viper57 [ Sat Feb 27, 2010 9:12 pm ] |
| Post subject: | |
Still No Answer Nobody has really been able to answer this question. We talk about mitigating, using remote racking etc but still no answer. What PPE is to be worn to verify a 480V bus >40 cal/cm^2 is deenergized? How about a panel mounted voltmeter? Would that be acceptable? |
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| Author: | 70E Arc Protection [ Thu Mar 11, 2010 9:02 pm ] |
| Post subject: | |
viper57 wrote: Nobody has really been able to answer this question. We talk about mitigating, using remote racking etc but still no answer. What PPE is to be worn to verify a 480V bus >40 cal/cm^2 is deenergized? How about a panel mounted voltmeter? Would that be acceptable?
This is easy, you need [url="http://www.shop.70earcprotection.com/product.sc?productId=3&categoryId=2"]HRC Level 4 Arc Flash Kit[/url]. 70E Arc Protection |
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| Author: | Zog [ Fri Mar 12, 2010 9:52 am ] |
| Post subject: | |
70E Arc Protection wrote: This is easy, you need [url="http://www.shop.70earcprotection.com/product.sc?productId=3&categoryId=2"]HRC Level 4 Arc Flash Kit[/url].
70E Arc Protection So are you claiming your "HRC 4 kit" will protect people from Ei's >40cal/cm2???? Or are you just one of those FR sales guys spammig this site? |
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| Author: | 70E Arc Protection [ Sun Mar 14, 2010 6:20 pm ] |
| Post subject: | |
I am sales guy but our Level 4 kit will protect you from a 40 Cal arc flash. As a sales guy that has sold protective clothing for over 10 years I believe that my contributions to this site have been valid. I will continue to contribute where I see a need and will continue to promote my site. |
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| Author: | JBD [ Sun Mar 14, 2010 6:30 pm ] |
| Post subject: | |
70E Arc Protection wrote: I am sales guy but our Level 4 kit will protect you from a 40 Cal arc flash.
The question was about PPE for greater than 40cal/cm². |
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| Author: | 70E Arc Protection [ Mon Mar 15, 2010 3:30 pm ] |
| Post subject: | |
We also have a kit for over 40 cal/cm2 , [url="http://www.shop.70earcprotection.com/product.sc?productId=5&categoryId=2"]Arc Flash Kit with 65 cal/cm2[/url]. |
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| Author: | jsharvey [ Fri Mar 19, 2010 2:22 pm ] |
| Post subject: | |
Help me out, I need some clarification 70E Arc Protection wrote: We also have a kit for over 40 cal/cm2 , [url="http://www.shop.70earcprotection.com/product.sc?productId=5&categoryId=2"]Arc Flash Kit with 65 cal/cm2[/url].
Maybe some that know a bit more about this than I do can set me straight. I was told in a 70e training class that anything greater than 40cal/cm2 you were pretty much in trouble. The suit may keep you from getting the major burns but the concussion and over pressure would in most cases crush your lungs and internal organs? Not that I'm going to be working on anything that needs a 65cal suit, that I know of right now, I'd sure like to know. Thanks. |
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| Author: | Zog [ Fri Mar 19, 2010 5:21 pm ] |
| Post subject: | |
jsharvey wrote: Maybe some that know a bit more about this than I do can set me straight. I was told in a 70e training class that anything greater than 40cal/cm2 you were pretty much in trouble. The suit may keep you from getting the major burns but the concussion and over pressure would in most cases crush your lungs and internal organs? Not that I'm going to be working on anything that needs a 65cal suit, that I know of right now, I'd sure like to know.
Thanks. Exactly, while there is technically not a "law" against using PPE for energized work >40 cal (Some some 70E handbook footnotes), there is more than enough test data to support the pressures can be unsurviable. The phrase "Open casket or closed casket" gets used a lot on this issue. That's why most such systems are labeld "Dangerous". |
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| Author: | GP_arc_Flash_MaN [ Wed Apr 21, 2010 7:37 pm ] |
| Post subject: | |
Zog that is absolutely correct. We also carry a suit that even incorporates kevlar into the blend of fabric @ 140 cal/cm2, but I always mention to my clients if you can avoid working on live energized equipment at that level DO SO!. Because honestly the difference would be an open or closed casket funeral. |
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| Author: | jedstump [ Sun Apr 25, 2010 6:50 pm ] |
| Post subject: | |
Zog wrote: No, and neither would a qualified person, PPE is still required for operating a 480V breaker with the door closed.
I think Zog answered this question quite well. PPE would still be required and of course a proper arc flash analysis performed to determine the level of protection required. |
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| Author: | fangle1948 [ Wed May 05, 2010 6:37 pm ] |
| Post subject: | |
jedstump wrote: I think Zog answered this question quite well.
PPE would still be required and of course a proper arc flash analysis performed to determine the level of protection required. How are people handling this for machine operator who lock out/tag out their machine during changeovers or cleaning? Most machines I've seen have an external handle to operate the main CB/disconnect inside the panel to disconnect the 480V feed. These would be operator tasks that do not open the electrical cabinet, but we must make sure that the electrical energy is removed to prevent machine operation. |
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| Author: | Vincent B. [ Sat May 08, 2010 4:05 am ] |
| Post subject: | |
fangle1948 wrote: How are people handling this for machine operator who lock out/tag out their machine during changeovers or cleaning?
Most train and equip their operators with specified PPE for this specific task (if you're using the table method, many manufacturing and/or maintenance machines fall under HRC0, which is usually easy to wear for operators). Another way would be to use a system such as Electroguard by Allen-Bradley: http://www.ab.com/safety/electroguard/product-demo.html It allows one to LOTO remotely, from multiple locations, for electrical, pneumatic and hydraulic power. Since it's remote, you're most likely outside the AFPB while operating it. Note the price tag though (couple tens of thousands). |
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| Author: | Zog [ Sat May 08, 2010 5:01 am ] |
| Post subject: | |
fangle1948 wrote: How are people handling this for machine operator who lock out/tag out their machine during changeovers or cleaning? Most machines I've seen have an external handle to operate the main CB/disconnect inside the panel to disconnect the 480V feed. These would be operator tasks that do not open the electrical cabinet, but we must make sure that the electrical energy is removed to prevent machine operation.
Remote switch operators allow them to operate the switch or breaker wirelessly from outside the arc flash boundary. http://www.cbsarcsafe.com/remote-switch-operators.htm |
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