Re: Motion Sensor Light for Front Entrance

["Josepi" <JRM.@xxxxxxxxxxxx>]

In the electrical utility field we calibrated most metering devices at zero
and 2/3 scale to acheive just what you said.

At 1000 watts I found 4 (units) Kill-a-Watt meters very accurate and within
about 0.2% of a lab standard  (traceable) over a fair range of pf. I cannot
remeber testing at the low end for the reasons stated above and by R.G.
below


"Robert Green" <robert_green1963@xxxxxxxxx> wrote in message
news:i7l9lo$fv7$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx

The Kill-A-Watt is notorious for not measuring very low wattage devices
accurately.  My electronic wizard friend theorized that it's because they've
optimized their reading range for items people would most likely measure.

I've been fooled by it on a number of occasions.  An in-line amperage
measurement is likely to show you something different.  Also, the X-10 power
supplies have a rather unusual design which contributes, I think, to the
Kill-A-Watt's erroneous readings.

IIRC, a while back Dave Houston (has anyone heard from him?) did some
measurements that more accurately pegged them at five watts. At the same
time I put a 7W nightlight and an appliance module connected to a load, one
after the other, in a small Styrofoam box and measured the heat rise.  The
X-10 module warmed the box a slight bit less than the 7w nightlight, but not
by half.  There are a couple of threads related to this in Google.

It was a while back and one of the issues was how much heat is generated in
the lamp module when it's dimming a very large load.  I know now that a
1000W resistive load makes it hot enough to melt into a big blob and lets
all the magic smoke out.  Experience is gained proportional to the amount of
equipment ruined. (-:

 If you were running them "no load" then you also weren't measuring the
trickle current a plugged in device draws.  I have over 100 modules,
controllers, AV-switches, telephone responders (one on each light to reset
the other when either locks up!), meters, loggers, repeaters, transceivers
and more so I just multiplied 100 by 4 as an average figure.  The rate the
power meter outside spins when I've shut off all the major loads tends to
confirm that all my X-10 gear draws more standby current than I wish they
did.  But even in biology, command and control requires a portion of overall
resources and your neurons are consuming tiny bits of energy just waiting
for a command from the brain.  (-:

If you have an in-line ammeter (the tong meters aren't really suitable,
either, you might want to revisit the study with loads plugged into a batch
of modules.  I'm tempted but my days of doing experiments in the name of
Usenet are fading.  I've learned that what my wife calls my "science
experiments"(especially those involving octupussed 110VAC electrical wiring)
have VERY low SAF.  The general SAF level seems pegged to the Dow Jones
average these days.

--
Bobby G.