House wiring? (slightly off-topic)

[J. Larry Hendry]

> ----- Original Message -----
> From: Dana Scott <danas at egosys.com>
> Also, try to measure the voltage at different times during
> the day.  7PM may be quite different from 1AM
> -Dana

Dana,
    That is a very good point I should have thought to mention, although it
should be within tolerance at all times.  Utilities employ MANY switched AC
capacitor banks.   While it can be efficient to move MW (in phase currents)
from generator to loads, it is virtually impossible to move MVAR (out of
phase currents) over much distance.  And, most of you may realize that MVAR
flow is the primary contributor to AC voltage drop since the largest
component of system impedance is not resistance. (we use big wire
<snicker).

Therefore, capacitor banks are scattered about the medium voltage
distribution system on poles nearer the loads they serve.  Most have
automatic voltage controls that switch them on and off depending on the
votage level.  In these days of utility cost cutting, maintenance of such
controllers is.... err..... "lower" on the priority list.  Therefore, it is
very possible for a capacitor to be "stuck" on line cause high voltages in
times of lower load.

In the US, the period of lowest demand falls consistently around 3 to 4 AM
for both summer and winter load cycles.  It is during this time that MVAR
sources normally exceed MVAR loads and voltage tends to rise.

So the short answer is check it around 4 AM.

Larry Hendry
who knows enough about this subject to bore even the most interested.
:)