For the sake of discussion, Most of this post is true. However there are
some statements that I do not totally agree with in opinion.

Danger arises when there is an electrical fault (leakage) from the hot
wire
or motor winding, etc., of a device to its metallic case.

Any path for an electric potential to be transferred to a person be it
metal, water or otherwise is a danger.

, the neutral is the same size wire and connected
to the ground at the panel. If it and its connections are good, it can do
the same thing.

Neutrals are current carrying conductors. A poor or open connection can
induce up to the full potential voltage on it.

Problems arise if the neutral is not well connected to ground at the box.

Neutrals are bonded to ground at the service to insure incidental voltages
induced in any circuit have a path to ground and not transferred to all the
wiring. ( Lightning strikes to a service or other conductor as an example.)

I've NEVER seen this happen in my 62 years.

In my experience, overheated connection failures are about 80% in neutrals.
Even on grounded device plugs. Never knew why....

BUT This is the government helping us by demanding a redundant
ground path.

The safety codes and rules are determined by tradesmen, fire officials,
engineers and insurance companies. People directly involved. The government
only tries to enforce them.


Most cheap table radios with tubes had no transformer and could easily get
their chassis hot to ground.

In many this was done intentionally as one supply wire was deliberately
connected to the 'isolated' chassis.

It should be said here that a device needing considerable power plugged
into
an outlet with a serious neutral fault would not work properly, because of
the voltage drop across the fault, so you might have some warning. A
device
that drew very little current might work well, however, since the drop
would
be small, but then a fault could occur to cause more current to flow,
burning out the fault and leaving the case hot and the device seemingly
off.
Bad News!

The current demand on a device would not determine an overload condition
from a single fault unless it was grounded with a separate conductor.
Burning out of the fault would disconnect the fault. Generally greatly
overloaded windings will cause insulation failure and short circuit within
the winding, draw excess current and more heating, also possibly causing a
ground fault, eventually destroying continuity of the windings stopping its
operation while still allowing that fault connection to an ungrounded
device.

I would welcome any corrections if I appear to be mistaken or misinformed.
--
Chipper Wood

useours, yours won't work

"Wilson" wrote in message
nk.net...
Welll, let's look at this. I'm not addressing code, or what you should
do,
just the facts.

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.

NOW, there are some errors in some messages. The third wire "ground" is
called that because it doesn't carry current. It is the same size as the
others so it can carry enough current to trip the breaker involved when a
fault occurs. It's there to suck up the fault current IF the neutral
wire
opens for some reason. BUT This is the government helping us by demanding
a redundant
ground path.

Yes, there IS current in the neutral and yes, it can be above ground by a
small amount (couple volts maybe) if high currents are flowing, BUT never
enough to be harmful. Problems arise if the neutral is not well connected
to ground at the box.. , but I
HAVE seen a commercial electrician switch hot and ground, making a bunch
of
equipment cases 120V hot! Imagine the spark when I connected a signal
cable
from this equipment to something else that was plugged into an outlet that
was properly wired! Thank heavens I didn't pick up the grounded device
while holding the metal connector on the cable!

At first thought, you might ask why not just connect neutral to the metal
tool case and be done with it. That would work, AS LONG as the outlets
and
plugs were properly polarized (different width prongs) and connected.
Unfortunately, old plugs were not polarized and newer ones can be
miswired.

Remember when "double insulated" tools were the rage? That was an
intermediate stage of development during which two insulation systems were
used. One was the regular motor insulation and the other was the plastic
case of the tool. This is MUCH better than the two wire metal tool.

Most cheap table radios with tubes had no transformer and could easily get
their chassis hot to ground. In this case, the user was protected only by
the case and knobs!

If you followed the above, you can see the temptation to use the neutral
as
a ground. In fact, it would work fine and be safe, UNTIL you had a
neutral
wire fault, putting your device above ground and making it very dangerous!
The GFI outlet is the right answer, unless you can pull new wire.

It should be said here that a device needing considerable power plugged
into
an outlet with a serious neutral fault would not work properly, because
of
the voltage drop across the fault, so you might have some warning. A
device
that drew very little current might work well, however, since the drop
would
be small, but then a fault could occur to cause more current to flow,
burning out the fault and leaving the case hot and the device seemingly
off.
Bad News!

I'd try to get good hookups in kitchens and laundry areas, but your
bedlamp
and table radio don't have many dangers, partly because they are not near
grounded metal, usually. Same for TVs, etc. A shop with a damp dirt floor
needs protection, especially if you are barefooted. The hand to hand
shock
is the most likely and most dangerous. The hand to foot shock tends to be
mitigated by non conductive shoes and dry floors.

Shocks in your left arm are more dangerous than in your right, because of
heart nerve location.

Let me know if anything above is misstated or confusing.

Wilson

"John Moorhead" wrote in message
. com...
Folks -

I have an old Victorian, Circa 1868.... The tenants trashed it, long
story.... Anyway, most of the electric outlets are two prong, rather
than
grounded.... I would like to put grounded outlets in, but I have only a
hot
(black) and neutral (white) No separate ground wire....

Would it be safe to install a 3 wire plug and have the ground and
neutral
common to the white wire? Would this work and be safe? Only having 2
prong
outlets has been a PITA, and getting under the house to run separate
grounds
would be a real bit of work. Would bridging the ground and common
terminals
also work and be safe with a GFCI outlet?

I would appreciate any remarks from those that KNOW and have experience.
The last thing I want is a fire....

I was under the house yesterday and found some old andirons.... All of
the
timber underneath is full dimension stuff, maybe even bigger....

Thanks in advance for any help that can be given....

John Moorhead