Thanks for your responses. Diver: I'm curious what Vd formula you use that is so confusing. I use this:
cmils = (2 x K x amperage x distance)
divided by voltage drop.
Where:
Cmils is the wire size in circular mils.
For copper, "approximate K" = 12.6.
For aluminum, "approximate K" = 21.2.
And my voltage drop in this situation would be 3% x 240v = 7.2v.
If, say,the aluminum portion of my run is 45 feet and the copper portion is 82 feet, my question is whether i calculate the aluminum circ mils by using a distance of 45' or by using the total distance of 127'. And likewise for the copper: would I plug 82' into the equation or 127'? Remember that there is no OCPD between the aluminum and the copper; they are simply spliced so that they are essentially acting as one feeder.
Does any of this change anyone's response?
