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 Post subject: TIA went too far?
PostPosted: Thu Sep 18, 2014 7:09 am 
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Section 2 of the TIA for 70E-2015 states, "Exposures ≥ 1.2 cal/cm2 to 4 cal/cm2: arc- rated
faceshield that covers the face, neck and chin
Exposures > 4.0 cal/cm2 to
and ≤ 12 cal/cm2: arcrated
faceshield that covers the face, neck and chin
and an arc-rated balaclava or an arc-rated arc flash
suit hood."

Where (I can't do strike-through in this forum), the BOLD text is delted. This means that a face shield is required for arc flash over 1.2 cal/cm^2 and "restores the text found in the 2012 edition of NFPA 70E."

Section 3 fixes another table in a similar fashion.

This isn't right. I went back and checked. The H/RC table (130.7(C)(16))requires a face shield starting at H/RC 1 (4 cal/cm^2), a balaclava starting atl H/RC 2 (8 cal/cm^2), and a hood exclusively at H/RC 3 (25 cal/cm^2). In the text in 130.7(C)(10) requires a hood starting at 12 cal/cm^2, The text is otherwise silent and although it says to use an arc rated face shield, it is never spelled out when the face shield becomes necessary. Table 130.7(C)(16) only applies when the H/RC tables are used so it cannot be used when an arc flash study is conducted, which I'm presuming is usually the case these days.

Annex H, Table H.2 further requires arc rated clothing only up to H/RC 2 (no face shield or balaclava required), then switches over to a full arc flash suit with arc flash hood for H/RC 3 or greater. Table H.3(a) and (b) adds to the confusion by requiring both a balaclava and face shield over 1.2 cal/cm^2, then switching to a full arc rated hood requirement over 12 cal/cm^2. The annexes are of course not part of the standard.

OSHA lists several details leading up to the revision to 269. Paraphrasing, NIOSH states that a face shield (no mention of balaclava) should be required above 4 cal/cm^2, and a hood above 8 cal/cm^2. OSHA states that their interpretation of the H/RC table in the 2004 edition of 70E requires a face shield for 5 cal/cm^2 (rounding is going on here), and a hood for 9 cal/cm^2 or higher. They then require a face shield starting at 9 cal/cm^2 for single phase arcs or 5 cal/cm^2 for 3 phase arcs, and then either a face shield and balaclava starting at 13 cal/cm^2 for single phase arcs, or 9 cal/cm^2 for three phase arcs. This is based on an assumption of a 30% reduction in energy from single phase arcs (guesswork on their part).

Honeywell/Salisbury gives PPE sets with a face shield starting at 4 cal/cm^2, adding a balaclava at 8 cal/cm^2, and switching to a hood at 12 cal/cm^2.

The conclusion I can get from all this is that the 2015 edition seems to be lowering the requirement for a face shield with a balaclava down to 1.2 cal/cm^2. Although I thought that this was pretty uniform because I had been going by the 2009 edition requirements for a long time, it is now very clear from a thorough check of the text that there is not agreement on the face shield requirement anywhere. The TIA only adds fuel to the fire and seems to be in agreement with Annex H but not what has been long standing in the H/RC tabular method, and Annex H itself is self-contradictory, and doesn't seem to agree with PPE manufacturers or OSHA recommendations.

What gives here? When is a face shield required? A balaclava? Is the combination an acceptable substitute for a hood altogether or is OSHA off base here? I'm totally confused now.


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 Post subject: Re: TIA went too far?
PostPosted: Thu Sep 18, 2014 8:12 am 
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If energy over 1.2 cal/cm^2 is considered to be dangerous, that means you need PPE to protect you at greater than 1.2 cal/cm^2. You should need to protect your entire head at that point, meaning a hood or balaclava/face shield combo is necessary at anything greater than 1.2 cal/cm^2.


PaulEngr wrote:
Section 2 of the TIA for 70E-2015 states, "Exposures ≥ 1.2 cal/cm2 to 4 cal/cm2: arc- rated
faceshield that covers the face, neck and chin
Exposures > 4.0 cal/cm2 to
and ≤ 12 cal/cm2: arcrated
faceshield that covers the face, neck and chin
and an arc-rated balaclava or an arc-rated arc flash
suit hood."

Where (I can't do strike-through in this forum), the BOLD text is delted. This means that a face shield is required for arc flash over 1.2 cal/cm^2 and "restores the text found in the 2012 edition of NFPA 70E."

Section 3 fixes another table in a similar fashion.

This isn't right. I went back and checked. The H/RC table (130.7(C)(16))requires a face shield starting at H/RC 1 (4 cal/cm^2), a balaclava starting atl H/RC 2 (8 cal/cm^2), and a hood exclusively at H/RC 3 (25 cal/cm^2). In the text in 130.7(C)(10) requires a hood starting at 12 cal/cm^2, The text is otherwise silent and although it says to use an arc rated face shield, it is never spelled out when the face shield becomes necessary. Table 130.7(C)(16) only applies when the H/RC tables are used so it cannot be used when an arc flash study is conducted, which I'm presuming is usually the case these days.

Annex H, Table H.2 further requires arc rated clothing only up to H/RC 2 (no face shield or balaclava required), then switches over to a full arc flash suit with arc flash hood for H/RC 3 or greater. Table H.3(a) and (b) adds to the confusion by requiring both a balaclava and face shield over 1.2 cal/cm^2, then switching to a full arc rated hood requirement over 12 cal/cm^2. The annexes are of course not part of the standard.

OSHA lists several details leading up to the revision to 269. Paraphrasing, NIOSH states that a face shield (no mention of balaclava) should be required above 4 cal/cm^2, and a hood above 8 cal/cm^2. OSHA states that their interpretation of the H/RC table in the 2004 edition of 70E requires a face shield for 5 cal/cm^2 (rounding is going on here), and a hood for 9 cal/cm^2 or higher. They then require a face shield starting at 9 cal/cm^2 for single phase arcs or 5 cal/cm^2 for 3 phase arcs, and then either a face shield and balaclava starting at 13 cal/cm^2 for single phase arcs, or 9 cal/cm^2 for three phase arcs. This is based on an assumption of a 30% reduction in energy from single phase arcs (guesswork on their part).

Honeywell/Salisbury gives PPE sets with a face shield starting at 4 cal/cm^2, adding a balaclava at 8 cal/cm^2, and switching to a hood at 12 cal/cm^2.

The conclusion I can get from all this is that the 2015 edition seems to be lowering the requirement for a face shield with a balaclava down to 1.2 cal/cm^2. Although I thought that this was pretty uniform because I had been going by the 2009 edition requirements for a long time, it is now very clear from a thorough check of the text that there is not agreement on the face shield requirement anywhere. The TIA only adds fuel to the fire and seems to be in agreement with Annex H but not what has been long standing in the H/RC tabular method, and Annex H itself is self-contradictory, and doesn't seem to agree with PPE manufacturers or OSHA recommendations.

What gives here? When is a face shield required? A balaclava? Is the combination an acceptable substitute for a hood altogether or is OSHA off base here? I'm totally confused now.


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 Post subject: Re: TIA went too far?
PostPosted: Wed Sep 24, 2014 10:32 am 
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Paul - go back to 70E-2012 130.7(C)(10) (b)(1) - An arc-rated balaclava shall be used with an arc-rated faceshield when the [back of the head is within the arc flash boundary.....An arc-rated hood shall be permitted to be used instead of an arc-rated faceshield and balaclava.
That language seemed to have stayed in the first draft of 2015, it wasn't till the second draft that added language pointed to balaclava use only if the incident energy was greater than 4 cal/cm^2. This change received 22 affirmations, with negatives being Palmer Hickman and Rod West pointing out the conflict with 130.7(C)(1) and 130.7(C)(6) that all parts of the body require protection when exposed to an arc flash energy environment - and the head is part of the body.

Interpretation? - I'll use this : any part of the body that has exposure to >1.2 cal/cm^2 requires protection against Arc flash


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 Post subject: Re: TIA went too far?
PostPosted: Fri Sep 26, 2014 1:44 pm 
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Voltrael wrote:
If energy over 1.2 cal/cm^2 is considered to be dangerous, that means you need PPE to protect you at greater than 1.2 cal/cm^2. You should need to protect your entire head at that point, meaning a hood or balaclava/face shield combo is necessary at anything greater than 1.2 cal/cm^2.


That's a big "IF", indeed. Using 1.2 cal/cm^2 as benchmark energy when deciding whether a PPE is required or not is unsafe. No more than 0.3 cal/cm^2 is required to cause 2nd degree burn when the energy is delivered within 0.01 sec time interval. Please read this forum thread at http://arcflashforum.brainfiller.com/viewtopic.php?f=34&t=2221 for more information. FYI, some have already accommodated the variable nature of threshold incident energy to second degree burn in arc flash analysis.


Last edited by wbd on Fri Sep 26, 2014 2:12 pm, edited 1 time in total.
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