this is interesting.

we have to have the AFC , if anything else , to comply with 110.16 (a component of the calc)

but in collecting the #'s for the AFC, if the impedance (of both the serving x-former, as well as the R value in terms of entrance conductor distance) is often minimal.

this results in much umph, so i was under the impression that 'series rated' was the only out..... my bad.... [Linked Image]

The siemens sentrons i've installed are only good to 200K IR ......how does one combat infinity? [Linked Image]