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70E-2009 Questions
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Author:  MIEngineer [ Mon Jan 19, 2009 9:14 pm ]
Post subject:  70E-2009 Questions
Hello All,

I have just received my copy of NFPA 70E-2009 and have a couple of questions about changes and outstanding issues I hope someone will be kind enough to help me with.

1) I see 130.3 Exception No. 1 was added to better align with IEEE 1584. I also see many people are assuming this to mean HRC = 0. Any ideas how that aligns with Table 130.7(C)(9) which has a few tasks at HRC 1 with <= 240 V rated equipment.

2) Is a lab coat-style AF clothing "legal" for any HRC level with nothing more than natural fiber clothing underneath?

3) Any idea on the rationale behind the hearing protection? Possibly due to the arc blast?

Thank you in advance.
Author:  Zog [ Tue Jan 20, 2009 7:37 am ]
Post subject: 
MIEngineer wrote:
1) I see 130.3 Exception No. 1 was added to better align with IEEE 1584. I also see many people are assuming this to mean HRC = 0. Any ideas how that aligns with Table 130.7(C)(9) which has a few tasks at HRC 1 with <= 240 V rated equipment.


Apples and oranges. Use the tables or the analysis, the assumptions are different.

MIEngineer wrote:
2) Is a lab coat-style AF clothing "legal" for any HRC level with nothing more than natural fiber clothing underneath?


No, you have to have full coverage, if you use a "lab coat" you need the leggings also. Arcs do very strange things, they dont do the same thing twice. See the videos here for some good examples. http://www.westexinc.com/

MIEngineer wrote:
3) Any idea on the rationale behind the hearing protection? Possibly due to the arc blast?


Yes, the pressure form the blast can rupture eardrums, this requirement has nothing to do with burn protection, the hearing protection is always covered with a hood or head sock for that.

Thank you in advance.[/QUOTE]
Author:  stevenal [ Wed Jan 21, 2009 6:06 pm ]
Post subject: 
A recent class showed the result after flashing a dummy with lab coat and leggings. The flash blew up in between, leaving the dummy with a burned crotch.
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