Standard kAIC ratings

[Keri_WW]

Do the major electrical companies (Square D, Eaton, etc.) all have a standard kAIC rating for the breakers?

10k
22k
42k
65k

Is that list correct, or are there other values available?

Thanks!
Keri

 

[C3PO]

Those are the standard ones that Square D does. I think you can get some at 5k, but I am not sure about that.

 

[jim dungar]

Do the major electrical companies (Square D, Eaton, etc.) all have a standard kAIC rating for the breakers?

The standard AIC ratings come from UL testing. So what you see from any one manufacturer is probably available from any other one.

The levels are voltage dependent therefore the standard ratings at 208-240V are not necessarily the same as those at 480V.

 

[Jraef]

It used to be like that, but not any more. As mentioned, it also depends upon the voltage class and amperage range you are speaking about. 480V class breakers for instance are now becoming somewhat standardized on 35k, 65k and 100k, but some manufacturers have 14k, 22k, 25k, 30k, 50k, 85k etc. etc. etc. You cannot assume anything any longer.

 

[hardworkingstiff]

You cannot assume anything any longer.

Ain't that the truth!

 

[Ranch]

UL was mentioned, but it is so important to understand interrupt ratings as they pertain to both UL and NEC.

For US installations, google this -

Understanding The impact of NEC Article 409 & UL 508A

 

[jim dungar]

UL was mentioned, but it is so important to understand interrupt ratings as they pertain to both UL and NEC.

For US installations, google this -

Understanding The impact of NEC Article 409 & UL 508A

NEC article 409 and UL508A deal much more with Short Circuit Current Ratings (SCCR) than they do with Amps Interrupting Capacity/Ratings (AIC/R). These are two independent issues. SCCR is the ability of a item to not fail while short circuit current is flowing through it (also see NEC 110.10). AIC is the amount of available short circuit current that an item can safely stop from flowing (also see NEC 110.9).

 

[Ranch]

These are two independent issues.

A good designer runs calculations to determine not only suitable SCCR ratings of circuit components but also the minimum AIC ratings of those protective devices that need to interrupt available short circuit current.

Independent categories (not issues) and they are side by side in the NEC. I prefer to look at SCCR and AIC at the same time. We are not fire fighters, we are fire preventers no?

 

[jim dungar]

A good designer runs calculations to determine not only suitable SCCR ratings of circuit components but also the minimum AIC ratings of those protective devices that need to interrupt available short circuit current.

Independent categories (not issues) and they are side by side in the NEC. I prefer to look at SCCR and AIC at the same time. We are not fire fighters, we are fire preventer's no?

NEC 409 and UL508A are two very limiting references (they only cover labeling of the SCCR of industrial control panels). The proper reference is NEC 110.10 which applies to all installed equipment including two of the most (in my experience) misused: automatic transfer switches and non-fused disconnect switches.

When you calculate the AIC requirements for a protective device are you making adjustments based on the X/R ratio of circuit?

 

[Ranch]

NEC 409 and UL508A are two very limiting references (they only cover labeling of the SCCR of industrial control panels). The proper reference is NEC 110.10 which applies to all installed equipment including two of the most (in my experience) misused: automatic transfer switches and non-fused disconnect switches.

When you calculate the AIC requirements for a protective device are you making adjustments based on the X/R ratio of circuit?

Jim,

Yes, I use X/R when I assess AIC.

This is extremely helpful. Thank you. I spend most of my time insuring devices inside the box are right. Your insight helps me on the outside of the box.

110.10 is on my radar ??