  Electrical power system calculations rely heavily on the $Y_{bus}$ matrix,
which is the Laplacian matrix of the network under study, weighted by the
complex-valued admittance of each branch. It is often useful to partition the
$Y_{bus}$ into four submatrices, to separately quantify the connectivity
between and among the load and generation nodes in the network. Simple
manipulation of these submatrices gives the $F_{LG}$ matrix, which offers
useful insights on how voltage deviations propagate through a power system and
on how energy losses may be minimized. Various authors have observed that in
practice the elements of $F_{LG}$ are real-valued and its rows sum close to
one: the present paper explains and proves these properties.
