Arc Flash Study

[steve66]

I am getting ready to do an arc flash study for a client. I have seen posts refering to the Utility Companies effect on the available bolted fault current.

Should I contact the utility and try to get them to pin down the available fault current?? I have also read IEEE reccomends calculating the arc flash energy at 100% of the bolted fault current, and at 85% of the fault current. Then you take the worst case. If I do that, I shouldn't need anything from the utility, right?

STeve

 

[jim dungar]

Re: Arc Flash Study

Actually, the IEEE standard says 100% and 85% of the available fault current, not the maximum. For example, what if the design maximum is 22,000A but the available is only 15,000A?

 

[ron]

Re: Arc Flash Study

Steve,
You need to start with the utility's available fault current best guess at this point.

 

[steve66]

Re: Arc Flash Study

Ok, I'll give them a call and see if they can provide any data.

STeve