For what it's worth, this 14 kA is a worst case number under the assumptions (a) that you have the lowest impedance transformer your utility deploys for a 120V/240V; (b) you have only 25' of conductor between the transformer and your panel; and (c) the primary wiring to that transformer has an infinite current capacity.
In practice, (c) is definitely false, (b) is likely to be a longer length, and (a) may or may not be true. Per the NEC, you only have to use equipment that can handle the actual fault current available at the equipment. So if you could get the actual transformer impedance, the actual length and size of conductors, and the actual transformer primary available fault current, a more accurate calculation could be done and may show that the actual available fault current is less than 10,000A.
Of course, the utility may have a policy that goes beyond the NEC and requires you to use the worst case numbers, which makes some sense for (a) [the utility could upgrade the transformer], very little sense for (b) [Is the utility really going to relocate the transformer without telling you?], and very little sense for (c) [is the utility going to open up a power plant next to your home, reducing the primary wiring length from the source to your transformer?] It's also true that the utility doesn't want to be bothered to provide more accurate data; or would charge for it, which along with the cost of an engineer to do the calculation and certify it, could approach the cost of the panel upgrade.
Anyway, thought this might be of interest in case you aren't already aware of this.
Cheers, Wayne
