Lineside AC connection and breaker AIC rating

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JoeNorm

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Let's say I want to connect to the utility side of a service in a residence. In this particular case it's for a solar connection. I've selected a QO enclosure that can house a singe two-pole breaker and is "suitable for service" rated. The breaker is a standard type that you'd use for branch circuits. The enclosure will be located within 10 feet of the connections to the lines.

Can I land the service side in the lugs of this enclosure and use this breaker for this purpose? I am confused whether I need a breaker with a higher AIC rating for this purpose? I have looked through most of the old threads on these topics but still need some help. Thanks.
 
The panel and breaker have to be rated for the AFC at the terminals. If this is a residential service it is not likely to be over 10K but it is possible. The POCO can tell you.
 
texie said:
The panel and breaker have to be rated for the AFC at the terminals. If this is a residential service it is not likely to be over 10K but it is possible. The POCO can tell you.
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Is this an NEC thing and something the inspector verifies?
 
tom baker said:
Your QO enclosure, its it main lug?
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This particular enclosure is main lug, yes. It has room for one, 2 pole breaker that functions as OCPD and a disconnect. I just checked and the enclosure is suitable for service, meaning it comes with a ground screw to optionally bond the neutral.
 
How are you going to do this? Will the existing main panel be next to this new small one? How are you going to split the service (where will you tap it and do you have room)? A 320/400A meter base is nice when you want two service disconnects since those are rated to be double lugged. Most residential meter sockets and panels can not be double lugged in the main breaker, meter, or MLO lugs. But change out the meter and you'd probably need the new single dwelling disconnect installed which just became a rule in the 2020 code.

This new panel may also need to be connected to the ground electrode system.
 
I agree with texi, 10K is fine 95% of the time for residential services. the most likely situation where you might exceed that, is where the poco is using a 50 or 100 k transformer because they are feeding a whole bunch of houses with it and/or one of the houses has a big load for some reason.

If you want to be safe, you can use a QO2XXH breaker which is rated 22k.
 
suemarkp said:
How are you going to do this? Will the existing main panel be next to this new small one? How are you going to split the service (where will you tap it and do you have room)? A 320/400A meter base is nice when you want two service disconnects since those are rated to be double lugged. Most residential meter sockets and panels can not be double lugged in the main breaker, meter, or MLO lugs. But change out the meter and you'd probably need the new single dwelling disconnect installed which just became a rule in the 2020 code.

This new panel may also need to be connected to the ground electrode system.
Click to expand...

If I’m not mistaken I can attach to the conductors in the main panel with listed connectors. There are provisions in the NEC for this.
 
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