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 Post subject: Manhole PPE
PostPosted: Thu Jan 08, 2015 9:24 pm 

Joined: Thu Jan 08, 2015 9:23 pm
Posts: 1
Hello everyone

I have a question about arc flash PPE requirements for performing electrical work in manholes. Specifically performing work in manholes when energized medium voltage cables are present, but not necessarily being worked on. I have not been able to find any specific info on such a case. So my question is what arc flash PPE would be required when working in a manhole around energized MV cables?

Thanks

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 Post subject: Re: Manhole PPE
PostPosted: Mon Jan 12, 2015 9:20 am 

Joined: Mon Jun 09, 2014 9:19 am
Posts: 43
In the 2012 version of the NFPA 70E, HRC 4 PPE was required to exam cables in a mahole or any other confined space per table 130.7(C)(15)(a). In the new 2015 version of 70E the tables do not mention anything regarding confined spaces or manholes. A cable inspection with no manipulation of cables does not require arc flash PPE. As part of my risk assessment for the task being performed in the manhole, I would take into consideration work being performed around the energized cables. If there is no danger of manipulating the cable in anyway, I would say you would be justified by not wearing the PPE.
My personal opinion though would be to wear arc rated PPE if you can. I have been around manholes when a cable explodes at our stations, the cover blows 30 ft into the air. The HRC 4 PPE recommended in 2012 may make a difference.


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 Post subject: Re: Manhole PPE
PostPosted: Tue Jan 13, 2015 2:14 pm 
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Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
Manholes violate the condition of assuming that there is plenty of space around the worker. Radiant energy can and is reflected back onto the worker, increasing incident energy even beyond the calculated result from IEEE 1584. Also escape is unlikely so a cutoff of 2 seconds is no longer realistic. Best way to deal with manholes is through actual simulated testing. Kinetrics has some mock ups and can either supply comparable data or do the actual testing.


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