The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
1 registered (sparkyinak), 245 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#185091 - 03/02/09 04:25 PM Fault current data & arc flash calculations?
Trick440 Offline
Member

Registered: 08/15/05
Posts: 248
Loc: Waterford, MI, USA
I have a commercial garage, that was done by an unlicensed electrican, without permits and was caught. So I get to be clean up guy. Clean up is going well except for this one issue that has me scratching my head...

"Provide fault current data & calculations & arc flash incident energy at working distance calculations at site for electrical inspection purposes."

This is just a plain repair shop. Plugs, lights, 2 lifts and me with no idea how to do these calculations.:)
_________________________
Shake n Bake

Top
2014 / 2011 NEC & Related Books and Study Guides
#185094 - 03/02/09 06:00 PM Re: Fault current data & arc flash calculations? [Re: Trick440]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Trick:
You can get some info on KAIC calcs at:

http://www.bussman.com/2/CooperBussmannLiterature.html

The 'SPD' and 'Plan Review' items provide a basic intro to
fault current calcs; point to point method.

The literature used to be 'free'; now I see 'purchase'. I have a few of these; 'either 02 or '05, if you're not in a big rush. PM me if you want.

The flash boundry calcs are not something I know how to do; I think it's best left to an engineer.

Why does the AHJ want all the calcs?



Edited by HotLine1 (03/04/09 02:43 PM)
_________________________
John

Top
#185097 - 03/02/09 07:16 PM Re: Fault current data & arc flash calculations? [Re: HotLine1]
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA


You can calculate the fault current available with this calculator from Siemens:

https://www.sea.siemens.com/consultant/docs/DA_SC_Calculator_V1.1.xls

You'll need to know the serving transformer's voltage, size and impedance, and the length, size, and conductor material of the feeder.

Top
#185101 - 03/02/09 08:37 PM Re: Fault current data & arc flash calculations? [Re: HotLine1]
Trick440 Offline
Member

Registered: 08/15/05
Posts: 248
Loc: Waterford, MI, USA
Thanks for the info and the calculator.

Originally Posted By: HotLine1
Trick:

Why does the AHJ want all the calcs?



I think thats the owners reward for not hiring a contractor and pulling permits. That and some additional inspection hours hes charging him for inspections.

_________________________
Shake n Bake

Top
#185102 - 03/02/09 08:52 PM Re: Fault current data & arc flash calculations? [Re: Trick440]
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Good Luck on getting the Available Fault current information on the transformer from the utility. They quit giving that out. "In the interest of saving money" Talk to Darrick.
_________________________
George Little

Top
#185104 - 03/02/09 09:01 PM Re: Fault current data & arc flash calculations? [Re: Trick440]
leland Offline
Member

Registered: 08/20/07
Posts: 856
Loc: Lowell area, Ma. USA
Originally Posted By: Trick440
Thanks for the info and the calculator.

Originally Posted By: HotLine1
Trick:

Why does the AHJ want all the calcs?



I think thats the owners reward for not hiring a contractor and pulling permits. That and some additional inspection hours hes charging him for inspections.



Funny how that works! perfectly legal as well! smile

I have never been asked for such information and have yet to find anyone who understands the new 70E statutes.

Misconceptions abound.I try,my head spins and off I go...Oh well.

Top
#185108 - 03/03/09 07:32 AM Re: Fault current data & arc flash calculations? [Re: leland]
ghost307 Offline
Member

Registered: 05/09/05
Posts: 884
Loc: Chicago Illinois USA
Here in ComEd territory the biggest 208V transformer that you can get from them is 750KVA. We just assume the fault current based on that and call it good we you can't get the actual value from the local utility.
_________________________
Ghost307

Top
#185112 - 03/03/09 09:07 AM Re: Fault current data & arc flash calculations? [Re: ghost307]
sabrown Offline
Member

Registered: 12/12/02
Posts: 297
Loc: Ogden, Utah, USA
You may be able to use the generic information for the arc flash hazard analysis if you meet all the requirements in NFPA 70E 130.3 exception #1. Otherwise you need an Electrical Engineer who has done the calcs before. The fault current used by assuming infinite source before the transformer (as for figuring minimum AIC rating for equipment) may easily leave you under protected during arc fault (see printed info from people such as Peter Walsh and Jim Phillips).


To do the AIC calculations, the above information is good.



Edited by sabrown (03/03/09 09:08 AM)

Top
#185124 - 03/03/09 03:03 PM Re: Fault current data & arc flash calculations? [Re: HotLine1]
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
Originally Posted By: HotLine1
Trick:
You can get some info on KAIC calcs...


Allow me to be picky. The correct phrase is "you can get some info on SCA calcs...".
AIC means Amps Interrupting Capacity - this is a rating supplied by the manufacturer you can not calculate it. It is only available by testing.
SCA is Short Circuit Amps - this is what you calculate.
SCCR is Short Circuit Current Rating - this equipment rating can be determined in the field.
NEC 110.9 and 110.10 require that your equipment be rated for the available SCA.

If you want an entire copy of the Bussmann 2008 SPD you have to pay for it. However I have found that you can download the individual sections, one at a time, for free.

Top
#185126 - 03/03/09 05:54 PM Re: Fault current data & arc flash calculations? [Re: JBD]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
JBD:
OK, you are allowed to be picky!

SCA that you calc result in a shall we say amperage figure that you use to determine the AIC of the buss bracing, and the OCP; right?

Based on the above I used the term KAIC, which is the basic end result of the calcs.

Perhaps my bad choice of terms.
_________________________
John

Top
Page 1 of 2 1 2 >



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals