AIC Rating

R

Rknrbn

New User
Location
WI
Occupation
Electrician
I'm building a 800 amp single phase service with a 38000 AIC rating. I have an existing 400 amp fused disconnect with proper AIC rating. I am upgrading and adding a 200 amp fused disconnect with the proper AIC that feeds a 10000 AIC rated main lug panel 150' away. I will also have a 200 amp main breaker panel with a 38000 AIC rating with a subpanel adjacent to that, with a 10000 AIC rating. So the 400 amp disconnect, the 200 amp disconnect, and the 200 amp main breaker panel are the 3 main disconnects equaling in 800 amps. Is this all correct and AIC ratings?
 
Your breakers, in the main light panel need to be series rated with your200A fuses, which they likely are, or you need to calculated available fault current after your 150' of conductors.
Your fused disconnects will need to have Class R fuse clips, which should be easy to do
 
Rknrbn said:
I'm building a 800 amp single phase service with a 38000 AIC rating. I have an existing 400 amp fused disconnect with proper AIC rating. I am upgrading and adding a 200 amp fused disconnect with the proper AIC that feeds a 10000 AIC rated main lug panel 150' away. I will also have a 200 amp main breaker panel with a 38000 AIC rating with a subpanel adjacent to that, with a 10000 AIC rating. So the 400 amp disconnect, the 200 amp disconnect, and the 200 amp main breaker panel are the 3 main disconnects equaling in 800 amps. Is this all correct and AIC ratings?
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Your fourth sentence….
This 200A panel is at your service entrance point and one of three mains, yes?
You have it rated at 38k, did not know that was a thing 10,14,18,22,25,35,42,65 and up. Minor point, but my question is how do you justify the adjacent sub panel at 10k?
I assume you are feeding via CBer in your 200A panel.
 
jim dungar said:
Your breakers, in the main light panel need to be series rated with your200A fuses, which they likely are, or you need to calculated available fault current after your 150' of conductors.
Your fused disconnects will need to have Class R fuse clips, which should be easy to do
Click to expand...
After 150 feet of conductor the available fault current at load end is likely under 10kA. Unless perhaps they are well oversized.
MyCleveland said:
Your fourth sentence….
This 200A panel is at your service entrance point and one of three mains, yes?
You have it rated at 38k, did not know that was a thing 10,14,18,22,25,35,42,65 and up. Minor point, but my question is how do you justify the adjacent sub panel at 10k?
I assume you are feeding via CBer in your 200A panel.
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That is a little confusing. If there is another 10kA rated panel near the service entry that supposedly has 38kA available, it may need more attention to the details. Is possible if it has Class R fuse ahead of it it may be series rated though
 
jim dungar said:
For something like this, I would use a simple on-line Short Circuit Calculator or the spreadsheet one I created way back 10 the 80's using Lotus-123 based on the hand calculations I used in college.
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No match professional engineering software ETAP, SKM etc
 
Deltaforce said:
Accuracy and reliability
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I assure the methods I mentioned are reliable and have enough accuracy for such a simple short circuit current analysis as in the OP.

The apps tend to not be as practice when the system is more complicated, especially when multiple circuits, transformers, and motors are involved. My spreadsheet was scalable to handle very complex circuits.
Remember, these SC and VD analysis were done by hand using slide rules and calculators for decades before software packages came out. Full power system studies including arc flash analysis is what drove many engineers into the Power Tools and ETAP markets.

In reality it is not the SC tool used that affects the result as much as it is the assumptions made when inputting data and interpreting the results.
 
nice - I might paraphrase and steal this:
...it is not the tool used that affects the result as much as it is the assumptions made when inputting data and interpreting the results...
 
kwired said:
Is possible if it has Class R fuse ahead of it it may be series rated though
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Cleveland, to check whether the breakers series rate, the information should be in the manufacturers catalog. Or, if you have a relationship with your vendor or the manufacturers rep, a simple phone call.
 
The OP asked, "Is this all correct and AIC ratings?"

To answer that accurately, we need a better understanding of what the OP already knows, rather than making assumptions.
Maybe he will clear it up more for plan review.
 
jim dungar said:
You have to make the calculation, you cannot go just with gut feel, whether it is 150' or 1.5'
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OK I did run it, gut feeling was pretty good if this were 208-240 volts, borderline if it were 480 volts.

OP didn't tell us voltage or type of system and wasn't clear if 38 K is what was actually available or if was rating of equipment only either.
MyCleveland said:
The OP asked, "Is this all correct and AIC ratings?"

To answer that accurately, we need a better understanding of what the OP already knows, rather than making assumptions.
Maybe he will clear it up more for plan review.
Click to expand...
Yes. I kind of assuming his mentioned 38k and 10k is equipment ratings but he never mentioned actual available fault current at the supply side terminals of said 38k equipment. But then many fused disconnects will have 100 or even 200kA rating if proper fuses are installed so still not clear what that 38k he mentioned actually is.
 
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