proper grounding

[Ken Maltby]

There is a justification for the safety ground here.

http://www.epanorama.net/documents/groundloop/neutral_ground_separate.html

I checked downstairs, and I cannot see how my panel is grounded.

I checked my water meter, and it has a substantial jumper wire and
clamps, on either side of the meter. Implying some code at some point
in time, wanted the cold water to have continuity to the street side.

But I cannot say exactly what my house wiring is relying on for safety
ground. I don't see anything big and obvious entering the panel.

The mast on the side of the house, has the usual three wires, but those
would be the two phases (115/115) and neutral.

The safety ground is engaged in two situations.

1) An equipment fault, causes live to contact the chassis of the
equipment. For example, the casing of your ATX PSU is probably
connected to safety ground. The metal chassis of the computer
comes in contact with it. If a live conductor were to touch the
chassis, it would be shunted to safety ground.

2) Switching power supplies use a little trick. They have EMI
filtering on the A.C. input side. The following device contains
the equivalent circuitry to the EMI filter function. The trick
is the two caps joined to "ground", which in this case the ground
is the safety ground. The caps divert high frequency noise (say
up to 30MHz or more) from the switching harmonics, to ground. But
the 120VAC also ends up being shunted as well. You can see in this
spec, that the "leakage" current is known and is not an accident,
and a device using this circuit is expected to have a proper safety
ground, to eat the 1.2 milliamps listed here.

http://www.cor.com/PDF/N.pdf

The leakage is enough, that if a three prong computer is plugged
into an improperly "safety grounded" outlet, the chassis of the
computer is raised above ground and is "hot". Each time the user
touches the chassis, and also touches something which is properly
grounded, they'll get a shock. There are occasional posters to
the newsgroups who suffer one of these shocks, and they don't
realize that their safety ground is not properly implemented
or is defective.

So if using a computer in a domestic situation, that is one reason
I'd want to verify that the safety ground is working.

Paul

Your Service Panel will have a grounded conductor terminal bar.
(Grounding Bus) One of the leads running from that will go to an
approved Grounding Electrode and to a connection on the water
pipe within 5' of its entering the building. There is also a Bonding
Jumper required around the water meter, if the grounding electrode
conductor is on the street side of the meter.

There are a number of accepted grounding electrodes/systems,
ranging from an 8' grounding rod to a complete counterpoise.
A "Ufer" ground, is a connection to 20' of reinforcing rod or
bare wire, buried in the foundation. You will defiantly have
a lead from the ground bus inside your service panel to an
approved grounding electrode.

Luck;
Ken

 

[w_tom]

I should add that you can add an equipment grounded outlet
to an existing ungrounded (two wire) circuit by connecting the
grounded outlet's ground to a grounded cold water pipe, but
the pipe needs to be tied into the building's grounding system.
(In many "older homes" that will be the case

Many assume electricity is same at both ends of a wire. If true,
then safety ground can be tied to white neutral wire. Reality is that
electricity is not same at both ends of a wire. Safety ground
(equipment ground) must connect directly back to the single point
safety ground - that bus bar in the mains box.

Connecting an outlet's safety ground pin to a water pipe is more
than a code violation. It can even mean that insurance has been
invalidated. Receptacle safety ground pin must connect to mains
breaker box ground bus bar.

Why is that ground wire still required to water pipe? All
connections to water pipes remove electricity from that pipe - for
human safety. The intent of the code is obvious. All grounding must
be by conductors dedicated only to grounding functions. Grounding via
items not defined for the purpose is a code violation and a threat to
human safety.

Either a three wire (grounded) cable must connect outlet to breaker
box, or outlet must be only a two prong type, or a GFCI must be
installed. Those are the options. Grounding electricity to any water
pipe is no longer acceptable and is a threat to human life.

 

[Ken Maltby]

On Jun 24, 11:21 pm, "Jon Danniken" <[email protected]>
wrote:


Given a choice between no grounded outlet and an outlet grounded to
water pipe, you either accept the ungrounded outlet as is, run a new
three wire romex from breaker box to outlet, or install a GFCI.
Recommending grounding to any water pipe is completely and totally
dangerous. Jon Danniken should know better - this tone because what
he proposes is not just wrong; it is also dangerous and not
acceptable.

Any electrical connection to any water pipe anywhere must be only to
remove electricity from that pipe. At no time is an grounding
connection made to a pipe to ground electricity. Safety ground wires
to pipes are to remove electricity from that pipe so that electricity
does not find earth ground via a human. No way around that reality.
Provided are three possible solutions. None ground to a water pipe
since that is nothing but dangerous, unacceptable, and recommended by
many who never grasped the bigger picture.

Not according to DeWalt or the NEC (National Electrical Code)
article 250. A cold water supply line can be an approved grounding
electrode. There are certain requirements for the supply line and it
must include at least a 20' buried run starting within 5' of where it
enters the building. The grounding electrode connector must connect
to the water supply line within 5' of its entering the building, and the
water meter must be bridged bonding both pipes (that entering the
meter and that leaving the meter).

An Equipment ground (that third grounded hole in a modern
outlet) can be made to a cold water pipe as long as the pipe
is bonded to the grounding electrode. If the water supply line
is the grounding electrode and there is no isolation applied to
the intervening pipe, (as would most often be the case in old
homes still wired with two hole outlets) then it is considered
bonded to the grounding electrode.

The equipment ground (the solid copper wire in the Romex)
returns directly to the Ground Bus at the Service Panel, in the
most common setups; this would need to be maintained when
adding to an existing equipment ground circuit. Where there is
no existing equipment ground circuit you can use the grounded
cold water piping to establish one for a run of outlets.

The real problems come if it is not done properly and/or there
are more than the one Equipment grounding circuits established.
(It's still possible to have several separate Equipment grounding
circuits, but they must be properly connected and in isolation
from each other otherwise.)

Just telling people they can connect the ground lead to a
water pipe, is dangerously misleading, without knowing the
precise conditions. If the home is old enough and not been
renovated and only has ungrounded two hole outlets and all
reasonable precautions are taken, it can be done without
causing any problems. But to be safe and legal you would
still need a certified electrician to bless it.

Luck;
Ken

 

[w_tom]

Not according to DeWalt or the NEC (National Electrical Code)
article 250. A cold water supply line can be an approved grounding
electrode. There are certain requirements for the supply line and it
must include at least a 20' buried run starting within 5' of where it
enters the building. The grounding electrode connector must connect
to the water supply line within 5' of its entering the building, and the
water meter must be bridged bonding both pipes (that entering the
meter and that leaving the meter).

An Equipment ground (that third grounded hole in a modern
outlet) can be made to a cold water pipe as long as the pipe
is bonded to the grounding electrode.

You have confused an earthing electrode - a completely different
ground - from equipment 'safety' ground. All outlets must be bonded
to a common point safety ground in the main breaker box. Only main
breaker box makes a connection to earthing - a completely different
ground. Equipment grounds remove electricity from equipment and pipes
to trip circuit breakers (and other functions). Equipment grounds all
meet inside the breaker box.

Does not matter that water pipe is 20 feet in earth. Earthing is a
completely different ground from equipment (safety) ground.
Electricty is different at both ends of a wire. Any connection from
wall receptacles to earth ground must be via that common point bus bar
ground inside main disconnect breaker box. This being only the first
reason why receptacles are never bonded to a water pipe.

If what you have posted is acceptable, then also acceptable is to
drive a ground rod outside the window and ground a receptacle to that
ground rod. That grounding also is not code acceptable. Safety
(equipment) ground and earth ground are two completely different
grounds.

Third, bonding a water pipe to breaker box serves a critical human
safety function. If dangerous electrical currents exist due 'fault'
into a pipe, then the bare copper wire that connects water pipe to
that breaker box bus bar will also protect humans - also connect fault
currents to the common safety ground bus bar. Its purpose is to remove
dangerous voltages from pipes. If that voltage is created by a fault
current is dumped into pipes by another wire, then that wiring fault
must be corrected / removed / disconnected. That latter wire
violates code and may even result in loss of insurance coverage. All
connections to water pipes - including the bypass around meter and
bypass around water heater - are part of a system (newer requirements)
only to *remove* electricity from pipes. Never dump a fault current
into pipes. That means never connect a receptacle ground or electrical
appliance ground to pipes. Never. And yes, that is a change from
code so many generations ago.

Fourth, no matter what pipe a plumber disconnects, disconnected pipe
must never compromise any safetyl grounds. If any safety ground is
dependent on a pipe, then a code violation exists. Whereas that
requirement did not exist generations ago, it does exist today.

You have confused two completely different grounds; have assumed
that electricity at both ends of a wire is same; have assumed safety
(equipment) ground is same as the earthing electrode. All safety
grounds meet at a common point - the main disconnect breaker box. An
earthing electrode connection is made only via that same box. A
receptacle connected to breaker box via cold water pipe violates a
common point ground principle, violates code, and even puts a
plumber's life at risk. All wires to pipes are to remove electricity
so that even a plumber is safe. If a plumber can do anything to pipes
that compromises any safety ground, then wiring is defective. It is
that simple. Never connect a wall receptacle ground to pipes.

 

[Ken Maltby]

You have confused an earthing electrode - a completely different
ground - from equipment 'safety' ground. All outlets must be bonded
to a common point safety ground in the main breaker box. Only main
breaker box makes a connection to earthing - a completely different
ground. Equipment grounds remove electricity from equipment and pipes
to trip circuit breakers (and other functions). Equipment grounds all
meet inside the breaker box.

Does not matter that water pipe is 20 feet in earth. Earthing is a
completely different ground from equipment (safety) ground.
Electricty is different at both ends of a wire. Any connection from
wall receptacles to earth ground must be via that common point bus bar
ground inside main disconnect breaker box. This being only the first
reason why receptacles are never bonded to a water pipe.

If what you have posted is acceptable, then also acceptable is to
drive a ground rod outside the window and ground a receptacle to that
ground rod. That grounding also is not code acceptable. Safety
(equipment) ground and earth ground are two completely different
grounds.

Third, bonding a water pipe to breaker box serves a critical human
safety function. If dangerous electrical currents exist due 'fault'
into a pipe, then the bare copper wire that connects water pipe to
that breaker box bus bar will also protect humans - also connect fault
currents to the common safety ground bus bar. Its purpose is to remove
dangerous voltages from pipes. If that voltage is created by a fault
current is dumped into pipes by another wire, then that wiring fault
must be corrected / removed / disconnected. That latter wire
violates code and may even result in loss of insurance coverage. All
connections to water pipes - including the bypass around meter and
bypass around water heater - are part of a system (newer requirements)
only to *remove* electricity from pipes. Never dump a fault current
into pipes. That means never connect a receptacle ground or electrical
appliance ground to pipes. Never. And yes, that is a change from
code so many generations ago.

Fourth, no matter what pipe a plumber disconnects, disconnected pipe
must never compromise any safetyl grounds. If any safety ground is
dependent on a pipe, then a code violation exists. Whereas that
requirement did not exist generations ago, it does exist today.

You have confused two completely different grounds; have assumed
that electricity at both ends of a wire is same; have assumed safety
(equipment) ground is same as the earthing electrode. All safety
grounds meet at a common point - the main disconnect breaker box. An
earthing electrode connection is made only via that same box. A
receptacle connected to breaker box via cold water pipe violates a
common point ground principle, violates code, and even puts a
plumber's life at risk. All wires to pipes are to remove electricity
so that even a plumber is safe. If a plumber can do anything to pipes
that compromises any safety ground, then wiring is defective. It is
that simple. Never connect a wall receptacle ground to pipes.

I see you are still full of it. See the NEC Section 250.81 or the
2005 DeWALT Electrical Licensing Guide.

I haven't confused or assumed anything and you can't restate the
situation from what I described in my post, to try and create a
faulty situation. We were describing where there was no existing
equipment/safety ground, a two wire ungrounded residential circuit,
and adding a grounded outlet. The receptacle is connected to the
existing breaker/fuse box via an extension of the existing two wire
circuit. The equipment/safety ground for the new added grounded
three hole outlet/receptacle can connect to a grounded cold water
pipe. The Ground-Fault Current path is through the Neutral, not
through the Equipment/safety lead/wire. Your idea of "removing"
electricity, would be laughable, if it didn't point out how misguided
you are.

Ken
---------------

 

[Bud--]

Does not matter that water pipe is 20 feet in earth. Earthing is a
completely different ground from equipment (safety) ground.
Electricty is different at both ends of a wire. Any connection from
wall receptacles to earth ground must be via that common point bus bar
ground inside main disconnect breaker box. This being only the first
reason why receptacles are never bonded to a water pipe.

Comments are based on the US 2005 National Electrical Code.
For an existing 2 wire circuit, a separate ground wire can be added that
connects anywhere on the grounding electrode system. That includes the
heavy wire to earthing electrodes. The NEC explicitly includes the water
pipe within 5 feet of the entrance to the house. In the past, connection
anywhere on metal water piping was permitted.

Third, bonding a water pipe to breaker box serves a critical human
safety function. If dangerous electrical currents exist due 'fault'
into a pipe, then the bare copper wire that connects water pipe to
that breaker box bus bar will also protect humans - also connect fault
currents to the common safety ground bus bar. Its purpose is to remove
dangerous voltages from pipes. If that voltage is created by a fault
current is dumped into pipes by another wire, then that wiring fault
must be corrected / removed / disconnected. That latter wire
violates code and may even result in loss of insurance coverage. All
connections to water pipes - including the bypass around meter and
bypass around water heater - are part of a system (newer requirements)
only to *remove* electricity from pipes. Never dump a fault current
into pipes. That means never connect a receptacle ground or electrical
appliance ground to pipes. Never. And yes, that is a change from
code so many generations ago.

“Remove electricity from pipes” is remarkably unclear writing. Anyone
competent in technical fields could do better.

Underground metal water pipe at least 10 feet length buried has for a
*very* long time been *required* to be used as a *grounding electrode*.
In the common case of an urban metal water supply system it will have a
far lower resistance to earth than any other electrode available at a
house. The connection for many years has been required to be within 5
feet of the entrance to the building with a bond across the water meter.

(If the underground pipe is not 10 feet metal the interior water pipe
must still be “bonded” to the service ground under almost the same rules
as if it was a grounding electrode.)

Because metal water service pipe may in the future be replaced with
plastic, for many years a “supplemental” electrode has been required.
This used to be 1 or 2 ground rods which are often only slightly better
than nothing. Starting with the 2005 NEC a Ufer/concrete encased
electrode has also been required for new construction with footings or
foundations. This is a good electrode.

Fourth, no matter what pipe a plumber disconnects, disconnected pipe
must never compromise any safetyl grounds. If any safety ground is
dependent on a pipe, then a code violation exists.

w_ apparently does not live anywhere the US NEC is enforced.


To the OP:

A ground to the outlet can be by metal sheath or a cable with a separate
ground wire. You can get an idea in the basement what wiring system you
have, although having a good ground in the basement does not guarantee
the ground is continued to the outlet in question.

If no ground is present can you move the computer to an area where a
good ground is present? Or where it is easier to add a ground?

It is a code and safety violation violation for someone to have added a
“grounded” outlet where there is no ground. A grounded–type GFCI
outlet can be installed, however, adding the sticker provided with the
outlet “No equipment ground”.

The ground test on a surge protector as well as the ground test on a
plug-in outlet tester will likely correctly indicate a problem.
Indicating a ‘good’ ground is not necessarily reliable because they test
at a very low current and will indicate ‘good’ on a very high ground
resistance.