Don't jump in too fast.

First: It is the _current_ through your body that does the damage. Voltage is
the electrical equivalent of pressure, (Yes, that is a very crude analogy,
OK?  :-) ), so higher voltage CAN drive a larger CURRENT.  So?  The farm
electric fence uses very high voltage pulses, sufficient voltage to easily
penetrate high resistance animal hair coats, etc. The CURRENT is limited to
about 25 - 30 milliamperes, a very, very painful shock.  Harmless, unless you
touch a steel fence post with one hand, grab the fence wire with the other,
and you are wearing a pacemaker.  That could be fatal. :-(  The farmer wants
to keep the livestock IN the pasture, NOT electrocute them.  :-)

Second: The neon tester will limit the current through your body to one so
slight that you cannot feel it at all.  This assumes that you use reasonably
dry hands to hold the tester. If you wet your hand with salt water, and stand
barefoot on a concrete floor that is in contact with good old mother earth,
you WILL get enough current to feel a shock, but not enough to harm you.  I
would like all of you to live very, very long lives.  

Third: Many of us get this List in Digest form.  In other words, we reply to
the last _Digest_ we received.  We do not know that you got our message
immediately, because you like to get zillions of email messages a day,
complete with all of those headers and footers. :-)  If you really are bored
and irritated because more than one person has "answered" your post, smile
before getting upset. :-)  Or, perhaps, think before you get so annoyed. It
is very probable that NONE of the persons who answered your post knows
anything at all about the OTHER  answers, because they all get Digests.
 Neither is aware the other has already answered you.  You may have read many
similar posts over the years. We may be completely unaware of the earlier
posts.  It happens.  These signals travel at the speed of light (slowed down
some because of travel through conducting wire, not through space) but it can
take hours, days, sometimes years to get a simple idea through a quarter inch
of human skull.  :-D

Fourth:  LIGHTEN UP!!!!!  :-)  :-)  :-)  I never "lecture," no matter how bad
the migraine!  I may not explain a process clearly enough to please you, but
then, all I was trying to do was be helpful.   Sometimes I succeed, sometimes
not.  I think the sun will come up tomorrow, no matter how badly or how well
I write.  Chlorophyl will still be green because it reflects green light.
 Anthocyanins will still form in leaves in the autumn.  Bees will still look
for UV sources, not human-sensed colored flowers.  Ohm's Law will still be E
= I / R.   And, I will still put signs on electrical panels saying "DANGER!!
200.000 Ohms!!!," and people will not get the joke. 

Fifth: recheck your math.  I think you misplaced a decimal.  Easy to do.
 Check your ohmmeter too.  Is the battery fresh?  How many Ohms per Volt?  It
does make a difference, especially with relatively high resistances. 

Sixth: DO NOT wet your fingers with salt water and firmly grasp the opposite
terminals of a 12 volt battery.   Likewise, DO NOT put the terminals of a
healthy nine volt battery on your tongue.  Not pleasant.  And, DO NOT put
your tongue on a cold pump handle when it is below zero outside.  Last, sit
and look at your beautiful tank full of plants.  A tank full of beautiful
plants.  Isn't that what we are trying for?  A really nice experience,
looking at that beautiful tank?  There are many paths to that goal, and there
should be plenty of room for plenty of approaches.  :-)

Now, I will let this post "sit" in my out box until tomorrow.  Sometimes in
the heat of inspiration, I get a great deal more testy than I intend.  Be
patient with me.  God is not yet finished with me. 

Yes, I WILL send it.  But - - - I stress the CURRENT as the problem, not the
voltage, precisely to correct a dangerous assumption.  A 24-volt system is
NOT safer than a 110.  It depends upon the exact circumstances, but please
remember, the Voltage is the rough equivalent of water pressure.  You can
drown just as dead in a very quiet, deep pond as you can in a fast running
stream.  If sufficient electrical current passes through your heart, you will
be dead, regardless of the voltage driving that current.  Please stay alive.