Are AIC ratings of equipment Line to Line or Line to Neutral

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steve66

steve66

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Illinois
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If I specify a 10,000 AIC breaker, is that taken to be L-L or L-N??

If I calculate 11KAIC Line to Line, and 9KAIC Line to Neutral, will a 10KAIC breaker or panel rating suffice?

Steve
 
My take would be No, and No, in that order. :roll: It is neither L-L nor L-N. It is the limit on the amount of current that can be allowed to pass through the breaker. Whether it goes through the breaker and through the fault and via the neutral back to the source, or whether it goes through the breaker and through the fault and through another breaker (or another pole of the same breaker) back to the source, it is still going through the breaker. So if you have a system that can push 11,000 amps through a breaker, then that breaker must be rated for at least that much current.
 
It depends on what the voltage rating is listed as on the breaker. For instance, if a breaker is rated 480/277, the AIC is based on the L-N voltage, so it CANNOT be used on a Delta system. If a breaker just lists a voltage by itself, it is rated at the L-L voltage; so a breaker rated 600V, the AIC is based on whatever the line-to-Line voltage is that you are using.
 
Jraef said:
It depends on what the voltage rating is listed as on the breaker. For instance, if a breaker is rated 480/277, the AIC is based on the L-N voltage, so it CANNOT be used on a Delta system. If a breaker just lists a voltage by itself, it is rated at the L-L voltage; so a breaker rated 600V, the AIC is based on whatever the line-to-Line voltage is that you are using.
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A slash rated breaker restriction is due to the L-G insulation in the construction of the breaker and not its AIC rating.

A three pole 480Y/277 breaker recieved its AIC level after being tested with a 3-phase L-L bolted fault. A single pole breaker can only have a L-N AIC rating. The published AIC of a multi-pole breaker is always a L-L rating (in fact, its L-N AIC level may be lower).
 
jim dungar said:
A slash rated breaker restriction is due to the L-G insulation in the construction of the breaker and not its AIC rating.

A three pole 480Y/277 breaker recieved its AIC level after being tested with a 3-phase L-L bolted fault. A single pole breaker can only have a L-N AIC rating. The published AIC of a multi-pole breaker is always a L-L rating (in fact, its L-N AIC level may be lower).
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D'oh! I know that. The slash rating issue has been coming up a lot for me lately and I find myself having to explain it to people who were completely unaware that it even existed. I jumped the gun a bit here. Mea culpa.

All I can say is, I need to stop posting late at night...
 
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