AC disconnect separation from service panel on solar system

[Fly_Dave]

The county electrical inspector wants me to perform a "Fault Current Length" calculation because he says my AC disconnect switch is too close to the main service panel. The distance between the two is about 1", which is the same as my first solar installation that was approved 3 years ago. This inspector says 6 feet is normal but I can meet the code if I show the 10 gage wire's length are sufficiently long via a fault current length calculation. I've downloaded a calculation spreadsheet and am waiting from the utility company to provide their utility fault current data for part of the spreadsheet's input. I'm confused by how much current drop is required between the service panel and the disconnect switch to meet code.

 

[electrofelon]

The county electrical inspector wants me to perform a "Fault Current Length" calculation because he says my AC disconnect switch is too close to the main service panel. The distance between the two is about 1", which is the same as my first solar installation that was approved 3 years ago. This inspector says 6 feet is normal but I can meet the code if I show the 10 gage wire's length are sufficiently long via a fault current length calculation. I've downloaded a calculation spreadsheet and am waiting from the utility company to provide their utility fault current data for part of the spreadsheet's input. I'm confused by how much current drop is required between the service panel and the disconnect switch to meet code.

for a fully rated system, you would need whatever conductor length it took to reduce the available fault current to the rating of the device. For a series rated system it may be acceptable without any conductor "drop" depending on if there is a series rating between the two devices.