Shock from car battery
artvand...@sbcglobal.net
can answer this. I was installing some car audio and hooked it up
directly to the battery. I used a wrench to unscrew the terminal and
did not get shocked (all metal wrench). However when I touched the
wrench to another piece of metal (accidentally) and the end still on
the terminal there was a good spark. Why was I not shocked? Would I
be if I was standing on earth ground instead of the concrete and with
rubber sole shoes? or is the voltage (I think 12 volts) too low?
Electronics Technician
Art,
True the voltage is too low to sense a shock as such. And the wrench
shunted most of the current to ground. However if you were sweating a
bit, holding the wrench and touch the same metalic strip with you
forearm you may sense a bit of a burning sensation. You would have
sensed the current. This situation can be much more dangerous.
When installing electronics devices always remember that ten milliamps
of current can kill you if it goes through you in the right way. Now
imaging the second situation only the forearm doesn't touch. You are
not wearing a shirt and your chest touches the metalic strip which is
ground. The current runs from the wrench through your chest then to
ground...you are sweating and your body resistance drops below 1200
ohms...you now have a potentially dangerous situation.
Why? Because 12 volts divided by 1200 ohms is 10 milliamps. If that
current should ground through you heart you may sense the current in
a very real way. Generally the body is said to have about 10,000 ohms
from head to toe but don't count on it.
I have never heard of anyone hurting themselves in this way but it pays
to becareful. Safety is a must.
Now imagine you are connecting a converter to a 600 volt battery and
you
are sweating. It's 113 degree's and your boots are wet from it. You are
standing on ground. You use the same wrench to remove the battery
terminal....I've seen this...The boots begin to steam. And you will be
lucky to turn loose of that wrench in time.
Or you touch ground with the wrench! Hopefully you will have saftey
glasses on if this should occur.
In short the manufacturers provide a terminal block to connect to.
Tape up the wrench and remove the battery terminal. Then connect the
fused line to the device you are installing to the terminal block. Make
sure the device is turnd off. And replace the battery terminal.
Happy Listening