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 Post subject: Can Anyone Define "Interacting"
PostPosted: Fri Jun 12, 2009 7:23 am 
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The 70E states as a definition of Arc-Flash Hazard, FPN #1, that "interacting with equipment in a manner that could cause an electric arc". What does this mean. Switching? Racking? There are lots of actions that could potentially cause an arc but in some instances equipment is designed to contain that arc with out letting it escalate to a fault. What are some examples of these so called interactions? Thanks in advance.

Maybe we always assume that if an arc is formed that it could escalate to a fault....not sure.


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PostPosted: Fri Jun 12, 2009 9:14 am 
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McFlash wrote:
The 70E states as a definition of Arc-Flash Hazard, FPN #1, that "interacting with equipment in a manner that could cause an electric arc". What does this mean. Switching? Racking? There are lots of actions that could potentially cause an arc but in some instances equipment is designed to contain that arc with out letting it escalate to a fault. What are some examples of these so called interactions? Thanks in advance.

Maybe we always assume that if an arc is formed that it could escalate to a fault....not sure.


Switching and racking are for sure, in fact the 2009 tables require HRC for all racking operations now, even with doors closed.

Besides ANSI arc rated switchgear the arc will most likely not be contained.

I would say any task listed in the tables would be an interaction.


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PostPosted: Fri Jun 12, 2009 10:11 am 
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FPN No. 2 says see Table 130.7(C)(9) for examples. But does this mean, as Zog suggests, that all listed tasks could cause an electric arc? How about those with a HRC of 0, like performing an infrared thermography inspection outside the restricted approach boundary on 120/240V panelboards or reading a panel meter while operating a meter switch on a 480V MCC?


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PostPosted: Fri Jun 12, 2009 3:34 pm 
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jghrist wrote:
FPN No. 2 says see Table 130.7(C)(9) for examples. But does this mean, as Zog suggests, that all listed tasks could cause an electric arc? How about those with a HRC of 0, like performing an infrared thermography inspection outside the restricted approach boundary on 120/240V panelboards or reading a panel meter while operating a meter switch on a 480V MCC?


Hmm, forgot about those new ones, I would say no to the IR, visual inspections, and meter reading ones.

Opening doors, racking, switching, etc... I think it is clear those are interactions.


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PostPosted: Mon Jun 15, 2009 5:57 am 
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Thanks for the comments and feed back. If you have the handbook it lists some examples right in the definitions....opening or closing a disconnecting means, pushing a reset button, or latching the enclosure door.


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PostPosted: Mon Jun 15, 2009 7:25 am 
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I wish there were something more definitive. Let's say you calculate an IE of 30 cal/cm² at a MCC. This requires an arc flash suit. Table 130.7(C)(9) lists starter operation with doors closed as HRC 0. Since you've done an arc hazard analysis, you have to use the 30 cal/cm² instead of the table HRC, but the table is used for examples of interacting with the equipment.

Now, say Snidley Whiplash has Nell tied to a log on a sawmill conveyor. Does Dudley Do Right don his arc flash suit before pushing the OFF button on the MCC?
:confused:


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PostPosted: Tue Aug 11, 2009 6:21 am 
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I've been in some debate lately over the meaning of the second sentence in FPN #1 of the definition of Arc Flash Hazard in NFPA 70E. In particular, I'm looking at the requirements for a machine operator if he has operating controls (pushbuttons, E-stops, etc) on a (closed) panel with an HRC>0. The sentence states, "Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard." My interpretation of this is that it is intended to give an exception to PPE requirements for normal machine operation. The counterargument is that the arc flash hazard is not likely but still present so PPE corresponding to the appropriate HRC must be worn. If this were the case, I would expect it to say these conditions "may" pose a hazard like the first sentence does. Further, if the PPE is required, would it be required any time you are within the flash protection boundary of a PLC controlled panel where the PLC could be performing these same actions automatically? Please share your thoughts/interpretations on this.

Thanks


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PostPosted: Tue May 10, 2011 7:49 am 
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PPE needed for operating breakers?

On site we use larger generators (100 to 150 KVA) with an Incident Energy between 2.01 and 3.5 cal/cm2 at the generator's main breaker.

Our site management is saying that since this is installed equipment, made with parts designed for the intended use, that operators are not exposed to a potential Arc Blast when they operate the main breaker under load.

We are still using the 2004 verision of 70E onsite. This version of 70E is not enlightening as to if the Arc Flash Protection Boundary is cancelled by removing 'exposure' to the energized component.

Even when considering the 2009 verision of 70E, 'interacting' is not well enough defined for site management to agree that PPE for the incident energy needs to be worn when operating the breakers.

Am I being a fussy old woman, or is there a real risk? If the risk is real, where in the codes (2004 or 2009) do I point to to tell management, "this is why operators must wear PPE."?

Thank you for your help.

G :confused:


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PostPosted: Tue May 10, 2011 8:31 am 
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That is a little bit of a grey area and leaves some interpretation to the owner. You may want to read this thread.

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


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PostPosted: Tue May 10, 2011 8:38 am 
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AZGerri wrote:
On site we use larger generators (100 to 150 KVA) with an Incident Energy between 2.01 and 3.5 cal/cm2 at the generator's main breaker.

Our site management is saying that since this is installed equipment, made with parts designed for the intended use, that operators are not exposed to a potential Arc Blast when they operate the main breaker under load.


The IE at the generator's main bkr, is that downstream of the breaker or with the breaker excluded? The reason I ask is that if you are operating that breaker, then there is no protective device upstream to open for the fault. So what PPE is required then? If applicable, use the 2 second cutoff and calculate the IE then without the breaker operating.

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PostPosted: Tue May 10, 2011 9:17 am 
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Still not clear

It seems to me that most people do not understand what interacting with means.

I know the 2009 handbook has a handbook note (so it isn't in the code, even as a FPN) that says that the 'technical committee' suggests that interacting with include operating a disconnecting means.

So
If 'operating a disconnecting' means includes opening or closing a breaker under load
and
If the computed incident energy is 3.0 cals/cm2 (same PPE as HRC 1)
and
If a person is within the Flash Protection Boundary (2.41 feet in this case)
then
Doesn't the 2009 code require that the person wear Arc Rated coveralls, etc.

Thanks.

:confused: Still :confused:
G


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PostPosted: Tue May 10, 2011 10:00 am 
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Ok, I am getting confused on what you are asking. If you are within the AFB while someone is interacting with a device, then you need to have the appropriate PPE on. Since it is a small AFB (<3 ft), I would wear the same PPE that the person interacting with the device is wearing. But safest approach is that if you do not need to be in the AFB while the device is being interacted on, then stay out of the area.

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PostPosted: Tue May 10, 2011 10:30 am 
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To PPE or not to PPE

Our Site management feels that if a person (Unqualified or Qualified Person) is operating a breaker where the incident energy (calculated at 18") for the breaker is 3.0 cal/cm2 and the Flash Protection Boundary is 2.4 feet (and they are within this boundary), then that person does not need to wear PPE since they are not 'servicing' the equipment and the breaker is enclosed in a panel.

I am trying to find some quote out of the code to convince them that operating a breaker places them within the Flash Protection Boundary, even if the dead front is on the panel, and they will need to wear PPE for an incident energy of 3.0 cal/cm2.

Very :confused: G :confused:


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PostPosted: Tue May 10, 2011 10:48 am 
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AZGerri wrote:
Our Site management feels that if a person (Unqualified or Qualified Person) is operating a breaker where the incident energy (calculated at 18") for the breaker is 3.0 cal/cm2 and the Flash Protection Boundary is 2.4 feet (and they are within this boundary), then that person does not need to wear PPE since they are not 'servicing' the equipment and the breaker is enclosed in a panel.

I am trying to find some quote out of the code to convince them that operating a breaker places them within the Flash Protection Boundary, even if the dead front is on the panel, and they will need to wear PPE for an incident energy of 3.0 cal/cm2.

Very :confused: G :confused:


Ok maybe this will help. in NFPA 70E-2009, Article 130.7(C)(9) contains 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 for instances where to state of the equipment is known to readily change..."

There has also been plenty of discussion in this forum on the issue of doors open and closed as relates to the PPE requirements. I believe the consensus of the forum was that credit can not be taken for the doors being closed unless it is specifically tested and rated arc resistant gear.

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PostPosted: Thu May 12, 2011 7:55 am 
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The rest of that quote is "(e.g., doors open or closed, rack in or rack out)"

I'm not an English major but...

Anyone who understands electricity, and we should be able to assume that the task group understand electricity, knows that one common 'change' to any electrical circuit is that it changes from 'on' to 'off'. Why would an educated group like this, who is talking to an informed audience, find it necessary to state something so obvious.

Maybe the inclusion of the 'doors open or closed, rack in and rack out' is defining a limited set of circumstance such as the operation of switchgear, and, readily change means to switch on or off, with the implied understanding that switchgear represents high energy loads.

I do not believe that the task group meant to apply the PPE with covers on rule to routine devices such as circuit breaker panels, and MCC buckets. Consider 130.7A "if a worker must approach an exposed energized electricxal conductor or circuit part with the AFP...some protective equipment is necessary." Why say 'exposed' if you they meant to include deadfront also? Also, 130.6.I talks about anticipating failure. It says 'when there is evidence that electrical equipment could fail' . If you try to say PPE is needed when doing any switching on any equipment, then you are also saying that all equipment demonstrates evidence of failure - which is not true.


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