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#76204 - 12/28/00 04:03 PM Flash Protection Calculation
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Anyone out there done this "Flash Protection Calculation" that's coming up in the next cycle?

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#76205 - 12/29/00 05:18 AM Re: Flash Protection Calculation
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
This is just a reflection of some OSHA regs that have been on the books for about 15 years. Few in the industry are doing the calcs or following the OHSA regs. The formula does not look too bad (it is in NFPA 70E) but I've not used it.
Don(resqcapt19)
_________________________
Don(resqcapt19)

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#76206 - 12/31/00 06:42 AM Re: Flash Protection Calculation
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
As I read the ROP;
110-16, new section;
Switchboards, panelboards, and motor control centers installed in other than residential occupancies shall be marked in the field to indicate energy in calories per square centimeter for a worker at 18"
FPN;
see NFPA 70E-2000 for the calc.

Emb=1038.7 Db 1.4738 TA ( 0.0093F(sq) + 5.9675)
Emb= incident energy
De=Distance fron arc in inches (18")
TA= Arc duration in seconds
F= bolted fault short circuit calc.

It looks as if they are defining what could easily be items that vary greatly, for instance, is 1.4738 an average arc duration? , does F,"bolted fault short circuit calc" apply only to the bolted variety of panelboards ? Why 18", is this an arbitrary distance ,relative to what? the average sparky's arm length? Is this the only means of providing this info, the only calc?

Don, I don't mind having to do this calc.if it's required ,I'm just having a little trouble with it's variables........

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#76207 - 12/31/00 08:25 PM Re: Flash Protection Calculation
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
I would never want to be the person or contractor that posts the calculation results on the panel. Too much exposure to future litigation. The calculation is only valid for the conditions that exist when the calculation is made. We shouldn't be working these panels hot anyway according to the OSHA rules, and if it must be worked hot under the few exceptions in the OSHA rules few of us have the required protective gear. I submitted a comment recommending that this proposal be rejected and hope enough others did too so that the panel will change its mind. The only people that will understand what the posted information means are the people that are already using the correct protective equipment and would be able to due their own calculations. Others will have no idea what this posted information means and will just continue their current practices.
Don(resqcapt19)
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Don(resqcapt19)

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#76208 - 01/01/01 04:30 AM Re: Flash Protection Calculation
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Well put......No argument here......

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