Hello everyone,

The application range for the empirical method is clearly defined : 208V to 15kV and a bolted fault current between 700A and 106kA.

But for the theoretical method, what is the applicable bolted fault current range ?
Can it be used for any voltage ?

The position about the type of bolted fault current is also not clear. Is it only for 3-phase fault ? Or 1-phase fault can be treated ?

How do you understand those ? Do you use another standard in case of you're out of one of the above range ?

The Lee theoretical equation is just that...theoretical. It does not have an application range as such. It is designed specifically for 3 phase bolted faults and the rest of IEEE 1584 should make it clear that no part of the standard applies to single phase faults.

In practice Lee does OK below 600 V but severely overpredicts incident energy as the voltage increases because it does not recognize that arcing voltage is almost constant at higher voltages. At the low end it severely overpredicts because it does not predict arc restriking accurately. It is also limited to open air conditions and does not accurately reflect the "focussing" effect that an enclosure has (arc-in-a-box).