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 Post subject: Cat 0 or Cat 2 PPE
PostPosted: Sat Nov 05, 2011 6:15 pm 
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Joined: Thu Jun 02, 2011 4:47 am
Posts: 3
Hi, Im from Austrialia,
We are currently using the US standards for our sites.

We have perfromed some sample sites. One issue I have is that a lot of the sites Distribtuion boards etc are Cat 0.
When we follow the table (in luie of an arc flash study) in NFPA it states that Cat 1- 2 is required for exposure to live part.

Should we advise our clients electrcial workers to use min Cat 2 for electrcial work regardless if it is a cat 0 switchboard?

Thanks for any advice, I have been following the fourm but until now havent asked any questions.
Thanks


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PostPosted: Sun Nov 06, 2011 1:33 pm 
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If the equipment is determined through the Incident Energy Analysis to meet the requirements to allow for CAT 0 PPE then that is that, no using the tables. If you are using the tables, which you stated are in lieu of the analysis, how have you determined the equipment ot be CAT 0?

I have heard of some sites using a canned scenario to determine, for example, given a short circuit finding the distance where the incident energy is increased. They then apply this scenario to other equipment instead of performing a specific study for each site.


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PostPosted: Thu Nov 10, 2011 1:39 am 
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Joined: Thu Jun 02, 2011 4:47 am
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We advised the client on typical worst case and released a table based on the sample site we did.
We are now performing detailed studies on each site.
When equipment is calculated to be cat0 , we still label cat 2 for electrical work on that equipment. We are concerned with the reliability of the switch gear and possible changes in fault levels, we are recommending that min ppe for electrical work ( testing , fault finding) is cat2. I did argue this with the head Engeneer and his view was better to be cat2 if an arc occurs than cat0. Do you think that is ok .


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PostPosted: Thu Nov 10, 2011 7:32 am 
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Joined: Wed Jun 04, 2008 9:17 am
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Location: Spartanburg, South Carolina
It is certainly OK to use a higher category PPE than the calculations indicate. Annex H of NFPA 70E describes a simplified two-category approach that could be used. You might also consider modified Cat 2 PPE (for example 8 cal/cm┬▓ rating but without the balaclava) for incident energies below 4 cal/cm┬▓.


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