Re: [a/s] Day 21 in Jackson Center

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

Sandy,
 Electricity behaves very much like water under pressure:

You can have a 100 PSI water source, feeding through a very small, long
line, and if the flow rate is very low or non-existant, the pressure
will be the same at the end of that long line. As soon as you open the
faucet, the pressure will drop, and the further you open it, the lower
the pressure. Note that the inlet pressure will be the same if that long
line is connected to a very large source line.

Same thing with power: if you have zero 'draw' (load), the voltage will
be exactly the same at the end of that long, long #18 cord as it is at
the source. As you increase the load, you start running into what's
called "voltage drop"; that's the difference between the source voltage
and the voltage at the end of the cord.

Now, I exaggerated a bit with the #18 cord (that's very light duty, like
lamp cord), but the principle is still there. If the campground is wired
with too-light cabling, the voltage will not be what it should be when
you turn on your A/C. Note that you're not alone on that cable, it feeds
a number of sites, and it's fed from a source that's not of infinite
capacity, so as the load increases, the voltage drops. You should be
aware of the fact that not all voltage drop comes from too-light wire;
bad connections will cause the same kind of drop.

Getting to specifics, the reason that electricity is F.M. to most folks
is that you can't SEE it, you have to use a meter(s) to see what's going
on inside those wires. If you measure the voltage at the campground
outlet, you might find 115VAC before you plug in your cord. It'll also
measure 115VAC inside your trailer as long as you have nothing turned
on. However, when you kick that A/C on, you might find that the voltage
drops to 110VAC or lower. Most A/C units don't like voltage much lower
than that, and I'd absolutely not run mine if the voltage dropped to
105VAC. Measuring the campground voltage is easy, as many (most?) have a
standard 20-amp receptacle in addition to the "RV" 30-amp job, and
they're almost certainly wired in parallel, even if they have
independant circuit breakers. Just plug your meter into the other
receptacle for measurements.

If you're able to measure the voltage at the campground outlet AND at
your trailer, you can note the difference, which is the voltage drop of
your cord. That's the reason you want to use a #10 cord, to make sure
that you get everything the campground has to offer. If the source was
right up there, say 120VAC and your cord was short, under 50', and the
connections were bright & shiney, you could easily get away with a #12
cable, but the heavier wire gives you a bit of insurance.

Once again, it's very important to measure the voltage UNDER LOAD. It'll
never improve, so if it's inadaquet before you fire up the A/C, you're
screwed, but you really, really need to know what it is when the A/C is
running. Note also that the voltage could be fine in mid-morning but be
way low in mid-afternoon when everyone else has his A/C running.

Radio Shack and others sell an expanded-scale voltmeter that simply
plugs into a handy receptacle. They're less than $20.00, which is quite
a bit cheaper than a new A/C.

                                          <<Jim>>