### Electrical Safety[]

```U.S.
PRESIDENTS
VIVE LE
RESISTANCE
ELECTRICAL
SAFETY
30 KV ABOVE
GROUND
“OHM” MY!
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WHO WAS PRESIDENT
WHEN ELECTRICITY
WAS INSTALLED IN THE
WHITE HOUSE?
BENJAMIN HARRISON

What is the
canonical value of
resistance for a
human gripping two
tips of a multimeter?
500 kW
I’m a resistor;
you’re a resistor!
Hooray, we’re all
resistors!
2013 Circuit class resistance (gripping tips of ohmmeter probes with dry skin):
Mean +/- std. dev 1.3 +/- 1 Mohm
Range: 105 kOhms – 3.2 MOhm
Canonical value: 500 kW (a reasonable ‘back of the pocket’ number to carry around)
Franco Colombo on Venice Beach circa 1960

WHAT UNIV. OF
CALIFORNIA PROF
STUDIED THE EFFECTS OF
ELECTRICAL CURRENT
ON ELICITING
INVOLUNTARY MUSCLE
MOVEMENT WHO LATER
INVENTED THE GFCI?
CHARLES
CHARLESDALZIEL
DALZIEL

“Don't think it's conductive?
Go stand outside in your
bare feet and hold a hot
wire. But before you do
make funeral
arrangements.” -Bill
Marsden

Is the bird shocked?

Why or why not?

Draw the circuit
diagram and explain
Never ever remove it!
Hot wire in
contact
with metal case
due to wear over
time
Can a toaster dropped into a bathtub electrocute you?
Crap….I dropped
my toaster in the
bathtub again
Develop an approximate circuit model a person soaking in a bathtub with an electrical appliance in contact with the water, then…
"I figured if I had the stamina to run four marathons, I
could take the brunt a good-humored 10,000 volt shock.
Not quite.
"The obstacle, the last of a few dozen, was 50 yards from
the finish line. What made it worse: There was a wait. A
line formed so we could watch people run through 50-60
dangling wires that charged with electricity every three
seconds…
"When it was my turn, I took off fast hoping to power my
way through.
"The first shock hurt like hell. If you've ever been shocked
before, you know how it feels. Intense pin-prickling pain is
followed by your extremities involuntarily flailing in all
directions.
"The second shock just about sent me to the ground. Mind
you, we were running over hurdles of dirt through the 20
feet of live cables. I almost made it until the third shock
hit. My legs left the ground and sent the rest of my body
face first into the wet mud.
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http://howelectricityworks.weebly.com/
http://science.nationalgeographic.com/science/photos/heart/
http://www.physics.ohio-state.edu/~p616/safety/fatal_current.html