C = (Eo * Er * A)/d
C = 2 * Pi * Eo * Er * ln(router/rinner) * length
C = Pi * Eo * Er * ln(D/r)*length
D is separation, r is radius, D>>r
NBS Circ 74, page 238, for 2 long wires above earth
C = 0.1208 * length / (log10(2 * D/d - D^2/(8*h^2)))
where D is distance between wires (cm),
d is diameter of wire (cm),
h is height above ground (cm)
hv/capform.htm - 9 April 2002 - Jim Lux