Available fault current

[mshields]

I thought I read either as a 2011 change or else where that the Available Fault current used for short circuit calculations now had to be based on infinite fault current on the primary of the service transformer? Is that true or do we still need to track the actual available fault current from the utility?

 

[don_resqcapt19]

Mike,
There is not any rule that I know of that says that. The new rule in 110.24 requires field marking of the available fault current on the service equipment at the time of installation.