proper grounding

[Skeleton Man]

Hi guys,

I went ahead and bought a new surge protector as per the lightning
discussion, but it indicates that it's not grounded !

The outlet itself is 3 prong, but the ground wire from the mains is screwed
to the metal box.. there is no ground screw on the outlet itself!

I have never seen an outlet in Canada/USA that has a ground terminal..
everyone always says just connect the ground wire to the box, so I presume
the metal tabs that screw the outlet to its box are supposed to provide the
ground ? (and then from the metal box to ground wire)

If this is correct it seems an awefully risky/stupid system.. I'm from
Australia originally and ALL our outlets use a ground screw.. there are of
course two wire cords for double insultated appliances, but there is NO such
thing as a two prong, non grounded outlet.. (at least not that I have
seen)..

I was thinking maybe it's the whole 120 vs 240v thing, but that would defy
logic because you have twice the current @ 120v..

Chris

 

[kony]

Hi guys,

I went ahead and bought a new surge protector as per the lightning
discussion, but it indicates that it's not grounded !

The outlet itself is 3 prong, but the ground wire from the mains is screwed
to the metal box.. there is no ground screw on the outlet itself!

I have never seen an outlet in Canada/USA that has a ground terminal..
everyone always says just connect the ground wire to the box, so I presume
the metal tabs that screw the outlet to its box are supposed to provide the
ground ? (and then from the metal box to ground wire)

If this is correct it seems an awefully risky/stupid system.. I'm from
Australia originally and ALL our outlets use a ground screw.. there are of
course two wire cords for double insultated appliances, but there is NO such
thing as a two prong, non grounded outlet.. (at least not that I have
seen)..

I was thinking maybe it's the whole 120 vs 240v thing, but that would defy
logic because you have twice the current @ 120v..

Chris

The typical outlet looks like the following and is available
from most hardware stores for about $0.40 each. Ironically
it often costs more per, to buy a 10-pack than individual
outlets.
http://www.levitonproducts.com/cata...sid=AA92D2E561A56452F4591C524E80FACB&pid=1208


If your don't have the ground socket, you might consider
replacing them or having someone else do it if you don't
feel qualified.

 

[Skeleton Man]

The typical outlet looks like the following and is available

from most hardware stores for about $0.40 each. Ironically
it often costs more per, to buy a 10-pack than individual
outlets.
If your don't have the ground socket, you might consider
replacing them or having someone else do it if you don't
feel qualified.

I know what a grounded socket looks like.. I'm guessing the silver screw at
the bottom left is ground ? The sockets I have seen are missing this screw,
but they ARE 3 hole outlets.. (there is a ground socket that accepts a 3
pin plug, but nowhere to attach a ground wire)

Chris

 

[RobertVA]

Hi guys,

I went ahead and bought a new surge protector as per the lightning
discussion, but it indicates that it's not grounded !

The outlet itself is 3 prong, but the ground wire from the mains is screwed
to the metal box.. there is no ground screw on the outlet itself!

I have never seen an outlet in Canada/USA that has a ground terminal..
everyone always says just connect the ground wire to the box, so I presume
the metal tabs that screw the outlet to its box are supposed to provide the
ground ? (and then from the metal box to ground wire)

If this is correct it seems an awefully risky/stupid system.. I'm from
Australia originally and ALL our outlets use a ground screw.. there are of
course two wire cords for double insultated appliances, but there is NO such
thing as a two prong, non grounded outlet.. (at least not that I have
seen)..

I was thinking maybe it's the whole 120 vs 240v thing, but that would defy
logic because you have twice the current @ 120v..

Chris

Note that electrical wiring varies in different countries!!!

Some outlet boxes aren't even metal, so they are not necessarily
grounded. There should be a green ground wire as one of the three
conductors in the cable from the distribution box. Someone MAY have
installed an improperly wired three prong outlet were there was
originally a two prong one as a poor substitute for using adapters for
three prong or polarized two prong plugs.

Ground is supposed to have the SAME electrical potential as the neutral.
A connection between either of the hot conductors and neutral provides
120V at 60 Hz. Since the two hot conductors are 1/120 of a second out of
phase, connecting between them (in household applications typically for
an electric range, water heater, clothes dryer or air conditioner/heat
pump) provides 240V (also at 60 Hz).

HIGHLY recommend the use of one of the inexpensive outlet testers
available in many North American home improvement centers to make sure
there are proper grounds in ALL your three prong outlets and to verify
the hot and neutral wires aren't reversed.

 

[Paul]

I know what a grounded socket looks like.. I'm guessing the silver screw at
the bottom left is ground ? The sockets I have seen are missing this screw,
but they ARE 3 hole outlets.. (there is a ground socket that accepts a 3
pin plug, but nowhere to attach a ground wire)

Chris

There is an alternative style here. The brass plate at the
top, implies they are picking up ground from the metal box.
So the metal box would need the green wire connected to it.

http://ec1.images-amazon.com/images/I/31PX3MQ17CL._SS500_.jpg

There are some alternative grounding schemes mentioned here.
Perhaps the code and method has changed over the years. The
introduction of plastic boxes would certainly change the
requirements on the receptacle design. They mention a pigtail
for ground, implying it is the installer's responsibility to
ensure ground is present, when mixing the wrong kind of component
parts.

http://www.ehow.com/how_117546_replace-receptacle.html

Paul

 

[Vanguard]

Hi guys,

I went ahead and bought a new surge protector as per the lightning
discussion, but it indicates that it's not grounded !

The outlet itself is 3 prong, but the ground wire from the mains is
screwed
to the metal box.. there is no ground screw on the outlet itself!

I have never seen an outlet in Canada/USA that has a ground terminal..
everyone always says just connect the ground wire to the box, so I
presume
the metal tabs that screw the outlet to its box are supposed to
provide the
ground ? (and then from the metal box to ground wire)

If this is correct it seems an awefully risky/stupid system.. I'm
from
Australia originally and ALL our outlets use a ground screw.. there
are of
course two wire cords for double insultated appliances, but there is
NO such
thing as a two prong, non grounded outlet.. (at least not that I have
seen)..

I was thinking maybe it's the whole 120 vs 240v thing, but that would
defy
logic because you have twice the current @ 120v..

So when you remove the cover plate and use a flashlight to look at the
cable coming into the box, does it have 2 or 3 wires? If 3 wires, where
do they go? I suppose only 2 of a 3-wire cable may actually enter the
box and the ground is outside the box and attached to the box but that
would only work if the box were metal instead of plastic (so you would
have to unscrew the metal box to look to see if a ground wire went to
it, and hopefully it isn't nailed into a stud).

 

[Jon Danniken]

Hi guys,

I went ahead and bought a new surge protector as per the lightning
discussion, but it indicates that it's not grounded !

The outlet itself is 3 prong, but the ground wire from the mains is
screwed
to the metal box.. there is no ground screw on the outlet itself!

Drill a small hole through the floor and run a copper wire (bare is okay)
over to a metal cold water pipe. Connect the wire to the metal cold water
pipe with the appropriate clamp device (a couple of bucks). Connect the
other end of the copper wire to the ground screw in your outlet, and you now
have a grounded outlet.

Jon

 

[Ken Maltby]

Drill a small hole through the floor and run a copper wire (bare is okay)
over to a metal cold water pipe. Connect the wire to the metal cold water
pipe with the appropriate clamp device (a couple of bucks). Connect the
other end of the copper wire to the ground screw in your outlet, and you
now have a grounded outlet.

Jon

****Warning******

That is a very BAD idea, and would violate many building
codes. Your building/home should have a common grounding
point, where the power line enters.

Luck;
Ken

 

[kony]

I know what a grounded socket looks like..

Then I don't understand what you meant when you wrote:

I have never seen an outlet in Canada/USA that has a ground terminal..

everyone always says just connect the ground wire to the box, so I presume
the metal tabs that screw the outlet to its box are supposed to provide the
ground ? (and then from the metal box to ground wire)

It could, but the ground wire to the outlet is better. Over
time an outlet might work itself loose from the box, and
this outlet frame-screw-box-ground wire is bound to be
higher impedance (though not a lot in ideal situations).

I'm guessing the silver screw at
the bottom left is ground ?
Yes


The sockets I have seen are missing this screw,
but they ARE 3 hole outlets.. (there is a ground socket that accepts a 3
pin plug, but nowhere to attach a ground wire)

Take a closer look at why it's not making electrical
connection to ground. Plug a lamp in to confirm power state
and flip the breaker/pull the fuse, take a multimeter and
check continuity/resistance... or just buy the $0.40 outlet
and install it.

 

[GlowingBlueMist]

****Warning******

That is a very BAD idea, and would violate many building
codes. Your building/home should have a common grounding
point, where the power line enters.

Luck;
Ken

True Ken,
I was almost killed when I grabbed an outside faucet to wash my hands after
installing carpet at a new house due to an electrician improperly using the
house water pipes as a ground.

The electrician had failed to keep up with the local building code changes.
Seems that a year or so the city in that area had switched to using a
plastic water line from the water main to two feet inside the basement, then
attached a water meter. From there the plumber had used copper water pipes
for the rest of the installation. A ground rod had not been installed by
the electrician outside the building and connected to both the ground lug
inside the circuit breaker box and the water pipes as per the "revised"
local building code.

At my request a city building inspector came out to the house to verify my
complaint about what had happened. This resulted in the building being
condemned and had the electrical meter removed pending the repair of the
wiring. They cancelled the license of the electrician who did the
installation and levied a six figure fine against electrician and the
company he worked for.

Every installation by that company going back three years were then
re-inspected by the city looking for similar problems.

 

[Skeleton Man]

There is an alternative style here. The brass plate at the

top, implies they are picking up ground from the metal box.
So the metal box would need the green wire connected to it.

http://ec1.images-amazon.com/images/I/31PX3MQ17CL._SS500_.jpg

That's exactly what I was talking about! (I thought I was going nuts when I
didn't see a ground screw on my outlets!!)

Not sure about the brass but it has metal tabs like that and the ground wire
attaches to the metal box. All the outlets here are wired like that, but my
surge protector tells me there's no ground connection.. (the ground wire is
definately attached to the box, and I followed the wiring all the way to the
breaker panel)

I don't have anything attached to ground that I could run an external ground
wire too either.. it would mean adding an extra wire all the way from the
outlet down into the basement onto a water pipe or something..

Chris

 

[Skeleton Man]

I know what a grounded socket looks like..
See Paul's post.. the style of outlet in the photo he posted is the same as
what I have.. no ground screw..

Chris

 

[Skeleton Man]

I never thought, if I can get the style of outlet that kony posted, that
should solve my problem.. assuming the ground wire is ok..

All I should need to do is test for continuity from neutral to ground right
? (the two are tied together at the panel right?)

Stupid question here, but.. if neutral is wired to ground as a return path
for electricity, if you removed the ground wire from the fixture (so it's
only path to ground was through you) and held it, would you get zapped ?
(obviously while it has a quicker path to ground, it's not going to take the
more resistive path through you)

Chris

 

[Skeleton Man]

I was almost killed when I grabbed an outside faucet to wash my hands after

installing carpet at a new house due to an electrician improperly using the
house water pipes as a ground.
The electrician had failed to keep up with the local building code changes.

Seems that a year or so the city in that area had switched to using a
plastic water line from the water main to two feet inside the basement, then
attached a water meter. From there the plumber had used copper water pipes
for the rest of the installation.

If I understand right, the common ground for the mains (joined to neutral)
was connected to a section of the copper pipes, but because of the plastic
section the water pipe was not grounded at all ? (hence 120V running through
all your faucets).

Chris

 

[Paul]

I never thought, if I can get the style of outlet that kony posted, that
should solve my problem.. assuming the ground wire is ok..

All I should need to do is test for continuity from neutral to ground right
? (the two are tied together at the panel right?)

Stupid question here, but.. if neutral is wired to ground as a return path
for electricity, if you removed the ground wire from the fixture (so it's
only path to ground was through you) and held it, would you get zapped ?
(obviously while it has a quicker path to ground, it's not going to take the
more resistive path through you)

Chris

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

 

[Jon Danniken]

****Warning******

That is a very BAD idea, and would violate many building
codes. Your building/home should have a common grounding
point, where the power line enters.

Yes, it should, but older homes don't have grounded outlets. For such
houses, there is nothing wrong with grounding to a metal water pipe, that's
why they sell the damn clamps in the first place, duh.

Oh yeah, this only works when the metal pipe goes through the ground,
another duh.

Seriously, given the choice between no grounded outlet and an outlet
grounded to a water pipe, you just ground the outlet to a water pipe. It's
been done hundreds of thousands of times, and it works fine if you use some
common sense.

Jon

 

[GlowingBlueMist]

If I understand right, the common ground for the mains (joined to neutral)
was connected to a section of the copper pipes, but because of the plastic
section the water pipe was not grounded at all ? (hence 120V running
through
all your faucets).

Chris

Sounds right to me.
Due to PVC (plastic) drain pipes in use the cast iron and stainless steel
fixtures and fittings were live as well because of the attached faucets.

 

[Ken Maltby]

Yes, it should, but older homes don't have grounded outlets. For such
houses, there is nothing wrong with grounding to a metal water pipe,
that's why they sell the damn clamps in the first place, duh.

Oh yeah, this only works when the metal pipe goes through the ground,
another duh.

Seriously, given the choice between no grounded outlet and an outlet
grounded to a water pipe, you just ground the outlet to a water pipe.
It's been done hundreds of thousands of times, and it works fine if you
use some common sense.

Jon

It would be a mistake to assume that all the readers of a post
will be exercising "common sense", and when dealing with mains
voltage, it's best not to assume at all.

Using separate grounds for signal equip. can work, (as long as
there is no interconnection). But when it comes to power circuits
you are risking creating a dangerous (to the equipment if not to
anyone who comes into contact) difference in ground potential.

Connecting all the grounds together, is one way to address these
issues, but it needs to be engineered into the building.

Luck;
Ken

P.S. "Older homes" are more likely to have buried metal water
supply pipes. There is the consideration though that many
"older homes" have, at some point, been "brought up to code"
and in the process had some plastic isolation from the water
main applied. If done properly,a grounding point would have
been properly established.

 

[Ken Maltby]

It would be a mistake to assume that all the readers of a post
will be exercising "common sense", and when dealing with mains
voltage, it's best not to assume at all.

Using separate grounds for signal equip. can work, (as long as
there is no interconnection). But when it comes to power circuits
you are risking creating a dangerous (to the equipment if not to
anyone who comes into contact) difference in ground potential.

Connecting all the grounds together, is one way to address these
issues, but it needs to be engineered into the building.

Luck;
Ken

P.S. "Older homes" are more likely to have buried metal water
supply pipes. There is the consideration though that many
"older homes" have, at some point, been "brought up to code"
and in the process had some plastic isolation from the water
main applied. If done properly,a grounding point would have
been properly established.

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.)

 

[w_tom]

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

Seriously, given the choice between no grounded outlet and an outlet
grounded to a water pipe, you just ground the outlet to a water pipe. It's
been done hundreds of thousands of times, and it works fine if you use some
common sense.

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.