Ampere Interrupting Current point to point calculation formula

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highpowered

Member
Location
los angeles
I have to show my calculations for 3 panels AIC/fault rating is sufficient. I’m changing out the 600 amp 4 wire 240/120v 4 wire (208v leg is on C) 3phase service because The main fuse is damaged and cannot Be turned off or on. Engineering will not let me submit this as maintenance(no new loads no change in amps) they have made me do full on plans. My final corrections are To show the 3 panels that are directly behind the switchgear(20-30’ of wire length) fault current is sufficient. Electrical engineer says because so close to panel it is not.
Ive done my due diligence and downloaded the excel sheet for this but for some reason i cannot input wire type or number of conductors? I would rather know the formula as I must show my calculations(point to point) anyway and I just want to know this moving forward?
Lastly any suggestions on continuing education for contractors in California ?
any help is appreciated
Thanks!
Jason S
 
kwired

kwired

Electron manager
Location
NE Nebraska
If you are talking about the fault current spreadsheet available from Mike Holt's main site, the formulas for most items is on the left side of the sheet.

You can also click on a cell with a calculated value displayed and the formula for how that value was determined will be displayed on the input line near top of screen.

As far as not being able to input certain values, maybe you did something that messed things up. Try closing the spreadsheet opening a new one and trying again? Presuming you have an original copy that has not been edited and then saved with the changes. Can always download original again if not certain.
 
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paulengr

Senior Member
The point by point method comes from the Bussmann (Cooper) fuse handbook. Even IEEE uses it in their 1584 spreadsheet. It’s much easier than the IEEE/ANSI method.
 
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