KAIC on Point of Interconnection OCPD < MSP

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MJRobinson

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Chico, CA, USA
The PV System main disconnecting means shall have ratings sufficient for the maximum available short circuit current that is available at the point if the PV system interconnectionn to utility.

Please provide fault current data for the existing electrical system, then match all new PV equipment rating witht eh existing AIC rating. 690.13(E); [2022 code 690.15(C)]
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We got this from AHJ. Our breaker (QJ23B200) has 10KAIC, the MSP (1000A has a KAIC of 50KAIC)

Are they saying that we need a 50AKAIC-rated fused switch and can only tap?

Doesn't make sense.
 
Yes, and not sure what you mean by only tap. A 200A fused main disconnect can easily reach the required 50KAIC. It may also be a requirement in your area that the PV system have a visible lockable disconnect, which this disconnect would satisfy. That's what we require here in Illinois.
 
MJRobinson said:
We got this from AHJ. Our breaker (QJ23B200) has 10KAIC, the MSP (1000A has a KAIC of 50KAIC)

Are they saying that we need a 50AKAIC-rated fused switch and can only tap?

Doesn't make sense.
Click to expand...
Maybe. It doesn't matter what the SCCR of the main panel is or what the AIC of the existing breakers in it are . What matters is what the available fault current at that point is. (Many people look at the existing equipment for ratings and assume that was done correctly and nothing has changed, but I always prefer to verify).
 
TallTimber said:
Yes, and not sure what you mean by only tap. A 200A fused main disconnect can easily reach the required 50KAIC. It may also be a requirement in your area that the PV system have a visible lockable disconnect, which this disconnect would satisfy. That's what we require here in Illinois.
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We have an Eaton DG324URK, perhaps they want it Fused?
"only tap", I meant line-side or a load-side tap with a fused disconnect.
 
electrofelon said:
Maybe. It doesn't matter what the SCCR of the main panel is or what the AIC of the existing breakers in it are . What matters is what the available fault current at that point is. (Many people look at the existing equipment for ratings and assume that was done correctly and nothing has changed, but I always prefer to verify).
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How do you think I can satisfy this requirement? I guess I should have had this in my question.
 
MJRobinson said:
We have an Eaton DG324URK, perhaps they want it Fused?
"only tap", I meant line-side or a load-side tap with a fused disconnect.
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That switch cannot be fused. With a standard breaker up stream that switch is only rated at 10KAIC, as Electrofelon said you will need to calculate your available fault current at that location. Then apply a rated disconnect for that determined fault current. The KAIC ratings do not indicate actual available fault current. The actual available can be less than the devices are rate for.
 
MJRobinson said:
How do you think I can satisfy this requirement? I guess I should have had this in my question.
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Well if the inspector just wants a 50kaic AC breaker then you could just do that. Here is a 42k if you can reevaluate the fault current and get it down a little bit....

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QJ22B200H SIEMENS 2 POLE 200AMP 240V 42KA CIRCUIT BREAKER NEW Surplus | eBay

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The 100k version is HQJ22B200H
 
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