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 Post subject: 30 Amp or Less
PostPosted: Wed Aug 04, 2010 8:13 am 
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We recently had our plant electrical analysis done. I was surprise that any machine panel 30 amp (480VAC 3PH) or less did not have to have an Arc Flash category label on it.

Why...

rmonroe


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PostPosted: Wed Aug 04, 2010 8:50 am 
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rmonroe wrote:
We recently had our plant electrical analysis done. I was surprise that any machine panel 30 amp (480VAC 3PH) or less did not have to have an Arc Flash category label on it.

Why...

rmonroe


They should be (110.16) even if they have a HRC of 0. It is the only way to know what the hazard or lack of hazard is.


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PostPosted: Wed Aug 04, 2010 10:02 am 
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rmonroe wrote:
We recently had our plant electrical analysis done. I was surprise that any machine panel 30 amp (480VAC 3PH) or less did not have to have an Arc Flash category label on it.

Why...

rmonroe


Some of the reasons I have personally been involved with:
Poor workscope for the analysis.
Lost cost bidder accepted where each bidder created their own device count.
Misunderstanding of the standard.
Not possible to fit a 6"square label onto a 5" disconnect.


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PostPosted: Wed Aug 04, 2010 12:09 pm 
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Please expand on your reasons...

Thanks

rmonroe


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PostPosted: Thu Aug 05, 2010 6:05 am 
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JBD wrote:
Some of the reasons I have personally been involved with:
Poor workscope for the analysis.
Lost cost bidder accepted where each bidder created their own device count.
Misunderstanding of the standard.
Not possible to fit a 6"square label onto a 5" disconnect.


Did the job specifications require it?
Was this a "you're the pro, you know what is needed" type of project, with the end goal to simply complete a study.
Did the people involved follow the current standard (NFPA70E- 2009)? Prior to this labels were not required, although the devices did need to be 'studied'.
Many times labels will not physically fit on small enclosures, especially labels that include a list of specific PPE components.


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PostPosted: Thu Aug 05, 2010 6:18 am 
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[font="Comic Sans MS"][SIZE="3"]Rich is right, NEC 110.16 explains the need for tagging. Besides, without an arc flash related label, how is one to know what FR rated clothing to wear?
NFPA 70E Article 130.3 exception 1 states:
An arc flash hazard analysis shall not be required where ALL of the following conditions exist:
1) The circuit is rated 240 volts or less
2) The circuit is supplied by 1 transformer.
3) The transformer supplying the circuit is rated less than 125 kva

Since you are referencing 3 phase 480 volts it appears to me your source for information is incorrect.[/size][/font]


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PostPosted: Thu Aug 05, 2010 7:19 am 
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Thanks for your input to my question...

rmonroe


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PostPosted: Fri Aug 13, 2010 10:10 am 
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The analysis is not required doesn't mean the tag/label is not required. That is my understanding.


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PostPosted: Fri Aug 13, 2010 11:25 am 
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Noah wrote:
The analysis is not required doesn't mean the tag/label is not required. That is my understanding.

If you don't do an analysis, what do you put on the label? HRC 0?


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PostPosted: Sat Aug 14, 2010 6:46 am 
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jghrist wrote:
If you don't do an analysis, what do you put on the label? HRC 0?


Reference the tables, typically the highest HRC for that equipment is used for the label.


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PostPosted: Sat Aug 14, 2010 2:49 pm 
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Zog wrote:
Reference the tables, typically the highest HRC for that equipment is used for the label.

If the equipment is a 120V panelboard, the maximum HRC in Table 130.7(C)(9) is 1. If it is served from 112.5 kVA transformer or smaller, an analysis is not required, implying no arc hazard would exist because the arc would not be sustained. Then why would would HRC 1 be required?


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PostPosted: Fri Nov 26, 2010 8:04 am 
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Is there regulation on the size of Arc flash labels? 4x6 is big to some small disconnect switches. I couldn't find anything from ANSI Z535.4-2002 regarding the size, if anyone can help, that will be great!


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PostPosted: Fri Nov 26, 2010 12:16 pm 
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Noah wrote:
Is there regulation on the size of Arc flash labels? 4x6 is big to some small disconnect switches. I couldn't find anything from ANSI Z535.4-2002 regarding the size, if anyone can help, that will be great!


There are no rules for the size, wording, or location of the labels, except they must tell what PPE to wear or provide the incident energy level. The NPFA70E committee as purposely not addressed the label specifics,as they feel these are best handled on a company by company basis.

Personally I feel too many companies put too much information on their arc flash labels, to the point they almost become ineffective.


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PostPosted: Tue Nov 01, 2011 7:56 pm 
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When I perform an Arc Flash Analysis, small equipment such as 30A or less disconnects that are not large enough to fit a label on, we use a smaller "general type cat 0" label specific for those type items. It has on it; Warning Arc Flash and Shock Hazard, Category 0, Appropriate PPE required, < 1.2 cal, 18" Arc Flash Protection Boundary, 10' Limited Approach Boundary, 1' Restricted Approach Boundary and 1" Prohibited Approach Boundary. Yet it's only 3" x 1.6". We only put them on small items such as that which would definetly be in the cat 0 range (some basic rules; 240V and less - fed by a single transformer less than 125 KVA and rated less than 200 Amp, 480 V and rated less than 100 Amp and not fed directly by a transformer). Perhaps the company that did your arc flash analysis can produce labels such as these.
I always tell people that equipment >50 volts that is small potential might not Require labeling, but we still apply labels for 2 reasons; there is actually a label on the equipment so people don't have to guess and there is still a shock hazard involved.
As a side note, yes 10' Limited Approach. We have increased it to a minimum of this distance as a safety consideration; it's easier to maintain when it's a standard distance such as this. Plus PPE we train to wear it within the FPB and basically emphasise the unqualified asspect of the LAB. If the FPB is more than 10' we will increase the LAB to match, and of course it can be more at higher voltages. Thus we also eliminate the possibility of unqualified employees entering the FPB but not the LAB (if it happened to be less) and not wearing appropriate Arc Flash PPE... and it's just a safer work practice.


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