ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
600 KW 120/208 3 Phase Y protection
by Yooperup. 07/21/17 09:27 AM
1913 American Electrician's Handbook
by gfretwell. 07/20/17 01:08 PM
Green House wiring
by ghost307. 07/20/17 09:10 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1. 07/18/17 08:06 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
239,225 Are you busy
174,625 Re: Forum
167,050 Need opinion
Who's Online Now
0 registered members (), 59 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#76204 - 12/28/00 08:03 PM Flash Protection Calculation  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Anyone out there done this "Flash Protection Calculation" that's coming up in the next cycle?


2017 / 2014 NEC & Related Books and Study Guides

#76205 - 12/29/00 09:18 AM Re: Flash Protection Calculation  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
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)

#76206 - 12/31/00 10:42 AM Re: Flash Protection Calculation  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
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........


#76207 - 01/01/01 12:25 AM Re: Flash Protection Calculation  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
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)


Don(resqcapt19)

#76208 - 01/01/01 08:30 AM Re: Flash Protection Calculation  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Well put......No argument here......



Member Spotlight
AllClear
AllClear
Belmond Iowa US
Posts: 44
Joined: August 2005
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.012s Queries: 14 (0.003s) Memory: 0.7677 MB (Peak: 0.9056 MB) Zlib enabled. Server Time: 2017-07-23 06:34:28 UTC