On 10/27/2015 9:58 AM, Frank wrote:
I was in the process of trying out some pushbutton receptacles to my floor
lamp light section, always making sure pulling out the wire from the wall
outlet before doing this when i attach the 2 wires to it. I must have tried
this at least a half dozen times, always making sure about the wire plug.
Finally, at the last attempt, i got the proper fit and added the bulb, turn
the little switch on the wire to test if the connections worked. It did, and
then to my surprise, I noticed that last time I did not bother to ever
remove that wire from the outlet. I thought, how come I did not get
electrocuted or at the least some shocked?

There must exist a path for the electricity to flow *through* your body
(or, some PART of your body). I.e., a place where it comes *in* and
a place where it goes *out*.

The easy way to get a shock is to let *both* wires come in contact with
your body. Note that one of the wires (the "neutral") is (theoretically)
bonded to the "safety ground" (third wire) back in your electrical panel.
So, you *should* be able to hold this wire and the "safety ground" with
no problem.

However, there is often a "potential" (voltage) across these two
(technical reasons not worth describing here). And, the safety
ground may *not* be connected properly. Finally, the "hot" and
"neutral" wires may be swapped, incorrectly. Bottom line, do
not try this. :

(there are other ways this can fail)

Because the neutral is connected to the safety ground (earth), grabbing
the *hot* and touching anything that is also connected to "earth"
(e.g., a water pipe) is effectively the same as grabbing hot and safety
ground (which we said was the same as hot and *neutral*) so you'll
get a shock.

Depending on the type of soil you have (and how recently it has rained,
etc.) standing barefoot on the dirt can have your feet acting like
a connection to "earth" so letting any part of your body touch "hot"
will result in a shock.

To get a shock, you need enough electrical potential (voltage) to
overcome the resistance of your skin. Typically, this is about
40 volts. As such, 110VAC qualifies!

[Note that you can get a tingle from a 9V battery if you hold it to your
tongue as there is far less resistance to overcome at your moist tongue
than at your dry hands!]

But, the voltage isn't what kills. Rather, it is the current -- the
"amount" of electricity (flow rate) passing through your body (from
the "in" point to the "out" point). If your *heart* happens to be
along this path, then, chances are, it will stop beating and that
will be the cause of death. One technique to minimize the chance of this
sort of path developing (assuming you are wearing insulated shoes)
is to keep one hand in your pocket while working on electrics;
with just one hand exposed to an electric circuit, there's less
chance of the "second point" being established for the current to
flow *through* your body (esp if that second point was YOUR OTHER
HAND -- with heart directly between them!).

[I.e., with one contact point, you're a bird perched on a high tension
wire -- safely!]

The length of time that you are exposed to the current also plays a
factor. For events where you *can* dislodge yourself (i.e., pull
your hand away from the "shock"), there is typically less risk
than for events where the muscles involuntarily contract, grabbing
the conductor even tighter (so the shock persists indefinitely)

If very high currents are involved (like grabbing onto a "high tension"
wire), then your flesh will actually *cook*.

Currents as low as 30mA (AC) can lead to fibrilation and, thus, death.
AC is harder for the body to cope with -- and our 60Hz is a particularly
bad frequency, in that regard. By contrast, DC currents need to be
considerably higher (an order of magnitude) to be of significant
concern.

[GFCI devices are designed to measure the amount of current going
"out" one conductor and returning back "in" through the other.
Any imbalance means there must have been some OTHER path for the
electricity to follow -- most likely through some *body*. This
"imbalance" is what causes them to trip.]