Available Fault Current After Main Service.

[ken.kenk]

This is an installation that I have run into. A commercial shop working on company equipment/office space. Single phase service 200 Amp. Service is created using a disconnect with fuses. There is a 40 space main lug only panel using 10K breakers. Calculated Available Fault Current at the service disconnect is 34,549. Granted the AFC is inordinately high just trying to get a worse case scenario going. the actual AFC is just above 16K

Is there a code violation here?

If not why?

 

[GoldDigger]

This is an installation that I have run into. A commercial shop working on company equipment/office space. Single phase service 200 Amp. Service is created using a disconnect with fuses. There is a 40 space main lug only panel using 10K breakers. Calculated Available Fault Current at the service disconnect is 34,549. Granted the AFC is inordinately high just trying to get a worse case scenario going. the actual AFC is just above 16K

Is there a code violation here?

If not why?

Could easily be. If the 10k breakers were designed in on the assumption that they are protected by the upstream fuses, then that combination has to be certified by the 10k breaker manufacturer or the fuses have to be current limiting to the degree required to allow the use of 10kA devices downstream.
16kA is still greater than 10kA.

You are more likely to get an acceptable series rating combination if you put the right main breaker in the panel to form a combination with the branch breakers.