Since g and b are components of admittance and either g, b or Y multiplied by voltage yields a current, they are all expressed in the same units, namely mhos.

From Kirchoff’s current law, I= I_L + I_R + I_C = V(Y_L+Y_R+Y_C)

Expressed in terms of their conductances and susceptances,

I=V(g₁-jb₁+g₂-jb₂+g₃-jb₃) = V[(g₁+g₂+g₃) – j(b₁+b₂+b₃)] = V(g₀ – jb₀)

Thus,

Conductances may be added arithmetically to obtain the resultant conductance
Susceptance must be added algebraically to obtain the resultant susceptance

That algebraic addition of susceptance is required is evident from the expression X/(R²+X²) for susceptance when it is remembered that X may be positive or negative depending upon whether it is inductive or capacitive respectively