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 Post subject: IR Scanning
PostPosted: Tue Oct 28, 2008 8:12 am 
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I have heard that there maybe a new provision in the 2009 NFPA which deals with PPE levels required for performing IR scans. Mention has been made of a "dotted line boundary" which would have a reduced level of PPE for the scanner. Is there any validity to this new rule?


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PostPosted: Tue Oct 28, 2008 8:58 am 
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blackdog wrote:
I have heard that there maybe a new provision in the 2009 NFPA which deals with PPE levels required for performing IR scans. Mention has been made of a "dotted line boundary" which would have a reduced level of PPE for the scanner. Is there any validity to this new rule?


The tables in the 2009 70E have IR scanning listed as a task that has some reduced PPE requirements, however the person pulling the panels will still need the right PPE for that task.


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PostPosted: Wed Oct 29, 2008 7:34 am 
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The "dotted line boundary" for infrared thermography is the Restricted Approach Boundary. The 2009 NFPA 70E has IR Thermography as:

Category 0 for 240V and below
Category 1 between 240V and 480V
Category 2 for 600V class switchgear
Category 3 for MV Switchgear through 38 kV and starters through 7.2 kV

Here's the catch:
These categories are subject to the footnotes that give maximum fault currents and clearing times so someone needs to determine these values. If you are outside these limits - time to perform detailed incident energy calculations. Also IE calcs could move you to a lower Category (or even higher)

The Restricted Approach Boundary is one of the boundaries for shock protection. You look it up in NFPA 70E. As an example 480V it is 12 inches - i.e. keep the camera back 12 inches from the live parts. This distance goes up with voltage.

I am uncertain how the short circuit and clearing time footnotes stack up with the restricted approach boundary. Normally, IE is calculated based on 18 or 36 inches from the live part. If you are 12 inches from the part (using the RAB) and there is an arc flash, it would be much worse since you are closer.

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PostPosted: Wed Oct 29, 2008 5:29 pm 
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Jim,
Couple of thought. NFPA needs to increase their time element from 2 cycles to 6 cycles min to open up the use of the table and include more installations. 2 cycles cutoff is way too limiting. 65KA is a bit on the high side, so if it helps they could reduce Ibf to 55K and still cover a much greater percentage of sites.

IR tech can always suppost their cameras off a KV rate pole so the camera goes closer and their body stays behind.

12" for the camer probably means 18" for the chest, so the IE numbers would be okay if based on 18"


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PostPosted: Thu Oct 30, 2008 3:23 pm 
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Good point Haze - Thanks!

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