On Thu, 08 Apr 2004 09:26:44 GMT, "Wilson"
wrote:

|Welll, let's look at this. I'm not addressing code, or what you should do,
|just the facts.
|
|Danger arises when there is an electrical fault (leakage) from the hot wire
|or motor winding, etc., of a device to its metallic case. Think electric
|drill with an insulation failure in the motor winding. For discussion,
|let's say the case is "connected" to the 120V hot wire. This device will
|work fine, but you'll be holding the 120V hot in your hand. Even that is
|fine, UNTIL you touch a "ground", like a water pipe or the case of a
|"grounded" appliance. At that point, YOU are a current carrying conductor
|and you will get a healthy (poor choice of word) ZAP. If you are really
|holding onto things, there is continuing current flow from arm to arm, about
|the worst way to get it, since it goes by your heart.


Exactly. Let me offer this personal example.

In my youth I worked in an automotive machine shop. The shop was in
an old building where all of the 110V (standard V in that era) wiring
was two-wire, i.e. no grounding conductor.

We installed an engine balancer and the wiring associated with that
equipment was brought up to code so it included some three-wire
outlets. I was the only person qualified to run the balancing
equipment and the rules were that accessories were to remain at the
balancing station and not to be used elsewhere in the shop.

One day I was balancing a crankshaft/flywheel/clutch plate assembly
and needed to drill a lightening hole in the clutch plate. The bosses
that centered the coil springs had extra material so the process was
to use reach through the middle of the spring with a 1/2" drill bit
and drill into the boss to take out some weight. Since the assembly
was resting horizontally on a set of precision low drag bearings it
was necessary to get a real firm grip on it to keep it from turning
and to apply the necessary force to drill the hole.

So I grabbed the far side of the ring gear with my left hand, cradled
the near side in the crook of my left elbow and with my right hand
stuck the drill bit, mounted in a heavy duty B&D or Milwaukee (I
forget which) 1/2 drill motor into the hole and pulled the trigger.

The shock I received was the worse I've ever experienced and after my
machine shop days I went into EE and between that and ham radio I've
been shocked many times. Since I'm still kicking I surmise that the
current was below the critical current that can cause fibrillation and
the point at which you can't let go.

When I recovered I discovered that some son of a bitch had used the
drill motor elsewhere in the shop and when he couldn't plug it in, had
cut off the ground pin on the connector.