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 Post subject: Arc-Flash Analysis - Dwelling Units
PostPosted: Thu Sep 01, 2011 8:59 am 

Joined: Tue May 24, 2011 5:52 am
Posts: 5
Is there a rule that legitimizes Arc-flash enforcement of 70E requirements in dwelling units? Article 90 in NFPA 70E states "public and private premises" but doesn't really call out dwelling units specifically. It also doesn't require an analysis in a system that has <240V, feed by <125kVA XFMR, and supplied by one XFMR (130.3 Exception #1). Also NFPA 70 does not require labeling inside dwelling units (110.16).

Thoughts on this matter?


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PostPosted: Fri Sep 02, 2011 7:35 am 
Sparks Level

Joined: Tue Feb 24, 2009 7:05 am
Posts: 252
Is that (or those) dwelling(s) a workplace? NFPA 70E's scope is some workplaces (not all, see the whole scope for exclusions).


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PostPosted: Fri Sep 02, 2011 8:16 am 
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Joined: Tue Jan 13, 2009 5:00 pm
Posts: 532
Doesn't it become a work place when the electrician shows up and begins a job?


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PostPosted: Fri Sep 02, 2011 9:19 am 
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
Good point, stevenal. I would say that homeowners do not have to label their panelboards, but electricians have to use the NFPA 70E task tables to determine what PPE to use.


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PostPosted: Fri Sep 02, 2011 9:25 am 
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
I have only ever seen one arc flash label in a residence, and my wife called me a dork for doing it :D


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PostPosted: Fri Sep 02, 2011 9:34 am 
Sparks Level

Joined: Tue Feb 24, 2009 7:05 am
Posts: 252
(Take it with a grain of salt)
What about the home office located in the basement and where the electrical panel of the house (standard 120/240V 1 phase) is in the closet of the office part? Would that require the owner to label it?


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PostPosted: Mon Sep 05, 2011 1:06 pm 

Joined: Wed Jan 19, 2011 6:30 pm
Posts: 3
Location: North carolina
OSHA doesn't inspect dwellings so I don't think you're required to label single family dwellings and its always been pretty much up to the individual to CYA


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PostPosted: Mon Sep 05, 2011 9:14 pm 
Sparks Level

Joined: Mon Mar 29, 2010 5:02 am
Posts: 136
And this is one area that can easily be taken over board... How many AF warning labels will be needed.. 30-50 BILLION?? I would love to have that contract for the printing...

IMHO...


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PostPosted: Tue Sep 06, 2011 7:48 am 

Joined: Tue May 24, 2011 5:52 am
Posts: 5
I understand the issues with labeling, but I'm just trying to get a grasp on enforcement during construction-like work. The job is at an army base, and we're starting to renovate some family housing units up to 2008 NEC. It's possible the contractor could have some type of run-in with exposed lines, but its a good chance they'll kill the power before any work is done. I was trying to get an idea of where enforcement can begin and end when it comes to dwelling units and arc-flash apparel. A hazard analysis has not been performed as all three items in exception 1 of the NFPA 70E article 130.3 are met. Can I only enforce conditions of shock avoidance (gloves, eye protection), or do you think the contractor needs to have arc-flash certification?

Thanks.


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PostPosted: Tue Sep 06, 2011 9:05 am 
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Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
Yes, for a civillian contractor arc flash PPE would still be required with or without a label. Even if they are only working on houses the employer/employee rules still apply IMO. They should still apply the tables and waer the proper PPE, and should have the proper training. Here is a form many companies use to "pre-qualify" contractors.


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PostPosted: Tue Sep 06, 2011 1:41 pm 
Sparks Level

Joined: Sun Dec 23, 2007 1:44 pm
Posts: 348
Location: Charlotte, NC
So if PPE is required for a 120/240 VAC single phase house panel, how do we calculate the IE level so we can choose the appropriate PPE? I would certainly think it should not be meltable type material. I haven't found anything in 70E that covers single phase.


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PostPosted: Tue Sep 06, 2011 1:53 pm 
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Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
My first inclination is to say use Table 130.7(C)(9) for Panelboards or Other Equipment Rated 240 V and Below. This table is not restricted to three-phase. The problem is Note 1. 25 kA is not usually a problem, but I can almost guarantee that the fault clearing time on the line side of the main breaker is more than 2 cycles if the upstream device is, as is normally the case, the utility transformer primary fuse.


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PostPosted: Thu Sep 08, 2011 6:28 am 

Joined: Tue May 24, 2011 5:52 am
Posts: 5
So a hazard risk analysis is not required, but we still assume certain arc-flash levels? Haven't studies indicated that single phase systems don't allow a sustainable arc? It just seems that in a single phase home application, shock and electrocution are the things to be worried about, and not necessarilly wearing PPE including a face shield. Does anyone know if single phase applications are going to be addressed in the new 2012 70E?

Sorry for all of the questions. Just want to make sure we implement and enforce the right procedures for our contractors out here.


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