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 Post subject: Arc Flash Studies - How often?
PostPosted: Tue Jul 01, 2008 1:04 pm 
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Joined: Tue Jul 01, 2008 10:41 am
Posts: 2
I am new to the world of arc flash hazard.

I understand OSHA has the power to levy fines for failing to institute the electrical installation standards of the revised NFPA 70E Sections 110.8(B)(1)(b) and 130.3(B), as well as NESC ANSI C2-2007 Section 410.A.3, which are published standards requiring an Arc-Flash Hazard Analysis (AFHA). The regulatory driving force behind these standards is found in OSHA 29 CFR 1910.132(d) and 1910.335.

The standards require arc flash analysis, but how often is an arc flash analysis done? Are they supposed to be done regularly? If so, how often?

Also, any ballpark numbers for costs? I sure costs vary with complexity and size, but any estimate of range of costs to perform the analysis would be helpful.

Thanks,
Barry Needle


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PostPosted: Tue Jul 01, 2008 2:01 pm 
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Joined: Sun Dec 23, 2007 1:44 pm
Posts: 348
Location: Charlotte, NC
Barry,

The standards, as you are aware, do not specify update intervals. I believe that it would be prudent to update a study, or part of it, when system changes warrant....ie..added equipment, replaced/upgraded equipment, conductor..etc. This can be from mods on your system or the utility supply system.

Since your electric service provider will not notify you if their system changes to increase or decrease the available fault current, I would contact them annually to obtain updated fault current availability so you will have it for your records. If it hasn't changed from the previous update, then you are good to go from there.

In general utility improvements will cause your fault duty to increase. If you see utility crews working in your area for weeks or months, then there is probably a major upgrade underway. If you see a new large fenced area and utility equipment being installed, you just may be about to be served from a new/larger substation and your fault duty is probably about to increase.

One of the major factors that will cause your fault duty to increase is that, if your facility grows it's electrical load, the utility may need to increase the size of your local service transformer. That alone would have a major impact with respect to increasing your available fault current.

While this is the usual case, other utility system changes could cause your fault current to decrease.

As far as cost goes, it could be from a few thousand to tens of thousands of dollars depending on your facility size and complexity.

Unfortunately, all of this is not so "cut and dried" as you have probably already noticed from other posts in this forum.

Hope it helps.
Alan


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PostPosted: Tue Jul 01, 2008 4:46 pm 
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Joined: Tue Jul 01, 2008 10:41 am
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Thanks, Alan. I appreciate the quick reply.
Barry


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PostPosted: Tue Jul 01, 2008 5:30 pm 
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Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
I good estimate is $100/point. A point is every label but also may include points that are not labled such as each breaker in a panel. Of course the costs can vary quite a bit but that thumbrule is pretty good for bugetary figures.


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PostPosted: Thu Jul 03, 2008 12:49 pm 
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Joined: Thu Mar 13, 2008 4:23 am
Posts: 25
Location: Canton, OH
I was told by an engineer at SKM that OSHA was going to require your arc flash study to be updated every 5 years.


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PostPosted: Fri Jul 04, 2008 8:23 am 
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Joined: Mon Apr 14, 2008 7:10 am
Posts: 142
In Canada, the new code CSA-Z462 section 4.3.3.1 provide a maximum 5 year interval for update. I was also told that arc flash study fee rate can be estimated as $3.00 per kVA. However, it is just for reference.


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