If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

because the case ground is by definition not a current carrying
conductor. I'm assuming you're referring to a dryer or range circuit in
the US. There are some 120VAC components in each so the neutral is
actually used. Useta be that you were allowed to use the ground as a
neutral, but no longer. Think about it, that would be kind of like
connecting the case of a metal tool like a hand drill to the neutral
prong of the plug... sure, it should *theoretically* be safe, but it
also increases the chances of something going wrong.

Now in the case of something like an A/C unit or a water heater, those
are pure 240 so they don't need a neutral, just the two hots and a
ground. If there *were* 120V components in those units you would then
need to pull 10/3WG or similar.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

On a 240V single phase circuit, a neutral is not needed. If you want to
run 120V loads then you need a neutral, but then it's a 120/240V
circuit.

On Feb 16, 6:04*pm, Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

The fussier journeymen in our part of the country prefer to use one
bus bar for grounds, the other for neutrals. Of course, the two busses
are bonded together. Other than looking really spiffy, I don't know of
any electrical advantage. Maybe one of our eminent electrical gurus
can shed some light.

Joe

The neutral and ground are run with two separate wires from the
receptacle to the panel because if they were both on the same wire and
that wire somehow opened between plug and panel, then the case of what
ever was plugged in would become "hot"' if any current was flowing
through the neutral. A real possibility f electrocution. Larry

Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Hi, Neut.
*
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
*
ground------*
/////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.

On Feb 16, 7:57*pm, Joe wrote:
On Feb 16, 6:04*pm, Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

The fussier journeymen in our part of the country prefer to use one
bus bar for grounds, the other for neutrals. Of course, the two busses
are bonded together. Other than looking really spiffy, I don't know of
any electrical advantage. Maybe one of our eminent electrical gurus
can shed some light.

Joe

Where there are more than one "ground bar" I use one for grounds &
one for neutrals.......

why? I'm not sure except that's the way I was shown and I was told
that grounds can be doubled up but neutrals cannot.

So by keeping them seperate it tends to enforce that behavior by
treating them as "different".
I guess that makes sense but in any case it works for me and the
wiring looks neater.

cheers
Bob

On Mon, 16 Feb 2009 20:53:58 -0600, "Pete C." wrote:


Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

On a 240V single phase circuit, a neutral is not needed. If you want to
run 120V loads then you need a neutral, but then it's a 120/240V
circuit.

But doesn't 120 volt also use a neutral and ground ????

Brian

On Feb 16, 11:32*pm, Tony Hwang wrote:
Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Hi, * * * * * * Neut.
* * * * * * * * * *
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
* * * * * * * * * *
ground------*
* * * * * */////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.


As someone else pointed out, the ground is there for safety. It's not
supposed to carry current, unless something goes wrong. For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted. The neutral is there to carry the normal current.
And if you had that connected to the metal case instead of the ground
wire, if the neutral came open or developed a high resistance for any
reason, all the metal case of the fridge and anything else on that
line as well, would have energized cases.

On Feb 17, 12:45*pm, Bubba wrote:
On Tue, 17 Feb 2009 06:21:14 -0800 (PST), wrote:
On Feb 16, 11:32*pm, Tony Hwang wrote:
Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Hi, * * * * * * Neut.
* * * * * * * * * *
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
* * * * * * * * * *
ground------*
* * * * * */////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.

As someone else pointed out, the ground is there for safety.

But yet, you trader are going to point it out again. Why? As you
always do. Wanting to reinvent the wheel just like all you boring
EE's.

It's not
supposed to carry current, unless something goes wrong.

Oh, so its not supposed to carry current but it will? You sound like
the weather man. "Today there will be a 50% chance of rain".
That pretty much covers your ass.

*For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted. *

Incorrect trader........as usual. You would only have a chance of
being electrocuted if you made a path to ground.

Oh please, Bubba. If the case becomes hot, I said you COULD become
eletrocuted, which is absolutely true. I don't have to list every
condition that must be in place for that to occur.



If your shoes are on
you wont make much of a path to ground.


After accusing me of giving being wrong, you state this whopper?

Bubba, go get your shoes on. Then go grab a hot wire in one hand and
touch a water faucet or the metal range with the other. You can wind
up dead with your shoes on. Also, only a fool would rely on shoes
as being adequate insulation. How about if they are damp?




So anyways trader, this is payback for your jumping on my heart valve
post.

IF you would like to keep this **** up, have at it. I can have
fun with you all day.
Have a nice life
Bubba- Hide quoted text -

- Show quoted text -

Bubba, you're the one here who keeps following folks around. First
it was Ransley you were after, now it seems to be me. In the other
thread, last couple days, you had a little war with Hank. Simple
fact is, you can't seem to get along with anyone here. Seems more
often than not, when you enter a thread, a flame war soon errupts.
Gee, wonder why that is?

Brian wrote:

On Mon, 16 Feb 2009 20:53:58 -0600, "Pete C." wrote:


Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

On a 240V single phase circuit, a neutral is not needed. If you want to
run 120V loads then you need a neutral, but then it's a 120/240V
circuit.

But doesn't 120 volt also use a neutral and ground ????

120V circuits normally use a neutral. Grounds are used on both 120V and
240V circuits. The ground is a non current carrying safety connection,
the neutral is the current carrying return path for the circuit.

On Feb 17, 2:18*pm, Bubba wrote:
On Tue, 17 Feb 2009 10:09:08 -0800 (PST), wrote:
On Feb 17, 12:45*pm, Bubba wrote:
On Tue, 17 Feb 2009 06:21:14 -0800 (PST), wrote:
On Feb 16, 11:32*pm, Tony Hwang wrote:
Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Hi, * * * * * * Neut.
* * * * * * * * * *
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
* * * * * * * * * *
ground------*
* * * * * */////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.

As someone else pointed out, the ground is there for safety.

But yet, you trader are going to point it out again. Why? As you
always do. Wanting to reinvent the wheel just like all you boring
EE's.

It's not
supposed to carry current, unless something goes wrong.

Oh, so its not supposed to carry current but it will? You sound like
the weather man. "Today there will be a 50% chance of rain".
That pretty much covers your ass.

*For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted. *

Incorrect trader........as usual. You would only have a chance of
being electrocuted if you made a path to ground.

Oh please, Bubba. * If the case becomes hot, I said you COULD become
eletrocuted, which is absolutely true. * I don't have to list every
condition that must be in place for that to occur.

OH wait a minute sweatheart. Now all of a sudden we dont have to be so
accurate? Bull****. Making up your own rules as you go along again?



If your shoes are on
you wont make much of a path to ground.

After accusing me of giving being wrong, you state this whopper?

Bubba, go get your shoes on. * Then go grab a hot wire in one hand and
touch a water faucet or the metal range with the other. *You can wind
up dead with your shoes on. * *Also, only a fool would rely on shoes
as being adequate insulation. *How about if they are damp?

First off, dip****, who walks around in their kitchen with wet shoes
besides some cupcake like you?
Second of all if I touch a cabinet of a refrigerator that happens to
have a bad ground while standing in my shoes in the kitchen Im NOT
going to be electrocuted you moron.


I never said if you touch the cabinet of a refrigerator with just a
bad ground you will get electrocuted. This is what I said:

"As someone else pointed out, the ground is there for safety. It's
not
supposed to carry current, unless something goes wrong. For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted."

Everyone else understood that to be a true statement. This is an
example of why you have such a hard time here in the newsgroup. You
start a flame war over something that was either totally taken out of
context or never said in the first place.




Now, tell me how that statement is wrong again you dumb bonehead.
EE's. What a pile of useless **** heads. Thinking they have the
correct answer to everything while not even knowing the basics of
anything.



So anyways trader, this is payback for your jumping on my heart valve
post.

IF you would like to keep this **** up, have at it. I can have
fun with you all day.
Have a nice life
Bubba- Hide quoted text -

and as it appears, you do want to keep going so, "Game On!"



- Show quoted text -

Bubba, you're the one here who keeps following folks around. * First
it was Ransley you were after, now it seems to be me. *In the other
thread, last couple days, you had a little war with Hank. * Simple
fact is, you can't seem to get along with anyone here. *Seems more
often than not, when you enter a thread, a flame war soon errupts.
Gee, wonder why that is?

A war with Hank!? What, was it one or maybe 2 posts at the most there
trader? Make up some more horse **** liar.
Oh, and now you wish to be mother to everyone on the internet?
You're a loser of a **** ant trader. Get a life.
Is that your mommy calling you telling you to get off the computer
now?
Bubba- Hide quoted text -

- Show quoted text -

On Feb 16, 7:04*pm, Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Brian

First things first. If it were in fact a 208,220,230,240 single phase
circuit it would have only three conductors.

In that case each of the two conductors that are neither bare
(uninsulated), green, or white would be the nominal phase voltage
relative to ground. The third conductor is the Equipment Grounding
Conductor (EGC). It might take the form of a bonded metal cable
jacket, cable tray, or a metallic raceway, or a wire much like the
other conductors of the circuit. If it is in the form of a wire it
will be either bare (Uninsulated) or green in color or if it is
American Wire Gage (AWG) size four or larger it would be color coded
green at all accessible points. The reason that the third conductor
can take the form of a metal enclosure around or supporting the
energized conductors is that it only carries current during a fault
condition. Provided that the EGC was properly sized and installed it
will carry the fault current so well that the Over Current Protective
Device (OCPD) that is protecting the faulted current carrying
conductor will open and thus clear the fault.

If the circuit is a dual voltage circuit, such as 120/240 volt North
American residential service range, clothes dryer, or feeder circuit
then it will have both 120 volt and 240 volt loads supplied from the
same circuit. In that case a forth conductor is run with the other
current carrying conductors. That grounded current carrying
conductor; which is commonly called the neutral; will be white in
color or may be coded white at all accessible locations. Under most
conditions of use it will be insulated and will not be supplied
through an OCPD.

Up until quite recently it was permissible to bond the chassis of
certain heavy appliances, such as stoves and clothes dryers, to the
neutral conductor that served the loads in that appliance. Under some
narrower circumstances the neutral conductor could be bare but never
green. Since certain uses, found mostly in residences supplied with
their own electrical service directly from the utility, the neutral
could be bare some confusion has developed as to whether it was an EGC
or a neutral. The code however was always clear that certain
appliance chassis could be bonded to the neutral instead of having a
separate EGC. The thinking was that these exception permitted
circuits were never smaller then number ten AWG and were nearly always
run from compression terminals to compression terminals so there was
little risk of an open or high resistance connection. Likewise the
feeder circuits were also run from and to compression terminals.
Experience has shown that, although they are rare, high resistance and
open conductors do occur in these circuits. Since the consequence of
such circuit failures was the energizing of the chassis of large
appliances or of the entire EGC system of separate buildings or feeder
supplied panels at 120 volts relative to ground this practice has now
been removed from the code and is only permissible in existing
installations that predate the respective code changes.

What was wrong with this technique is that it violates a basic
principle of safety engineering that holds that it should always take
two or more failures in the system, at least one of which is easily
recognizable as a condition that requires correction, to create an
immediate hazard to life or health. With the four wire circuit any
open in the neutral causes noticeable undesired operation such as the
dryer not coming on or the stove's light and controls not working.
Most importantly the undesired operation does not occur simultaneously
with an immediate deadly hazard so that the users are unlikely to put
up with the condition long enough for a complimentary fault to occur
which would turn the situation hazardous.

I hope that is helpful
--
Tom Horne

On Feb 16, 6:04*pm, Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Already answered, but...

The prime directive is that the neutral ALWAYS carries a load and the
ground NEVER carries a load, the ground just travels around to bond
everything providing a return path that becomes available as a safety
ground. If you allow the ground wire to carry a load, the circuit
will "work" but be unsafely and ungrounded. This is the reason you
never re-bond the ground in a subpanel, (it would make the ground
carry load between the panels), you just ground the subpanel and only
bond the neutral to the bus in the subpanel without re-bonding the
ground wire.

Brian posted for all of us...


If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Really did a lot of research did ya?

--
Tekkie Don't bother to thank me, I do this as a public service.

On Tue, 17 Feb 2009 14:18:57 -0500, Bubba
wrote:

On Tue, 17 Feb 2009 10:09:08 -0800 (PST), wrote:

On Feb 17, 12:45Â*pm, Bubba wrote:
On Tue, 17 Feb 2009 06:21:14 -0800 (PST), wrote:
On Feb 16, 11:32Â*pm, Tony Hwang wrote:
Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Hi, Â* Â* Â* Â* Â* Â* Neut.
Â* Â* Â* Â* Â* Â* Â* Â* Â* *
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
Â* Â* Â* Â* Â* Â* Â* Â* Â* *
ground------*
Â* Â* Â* Â* Â* Â*/////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.

As someone else pointed out, the ground is there for safety.

But yet, you trader are going to point it out again. Why? As you
always do. Wanting to reinvent the wheel just like all you boring
EE's.

It's not
supposed to carry current, unless something goes wrong.

Oh, so its not supposed to carry current but it will? You sound like
the weather man. "Today there will be a 50% chance of rain".
That pretty much covers your ass.

Â*For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted. Â*

Incorrect trader........as usual. You would only have a chance of
being electrocuted if you made a path to ground.

Oh please, Bubba. If the case becomes hot, I said you COULD become
eletrocuted, which is absolutely true. I don't have to list every
condition that must be in place for that to occur.

OH wait a minute sweatheart. Now all of a sudden we dont have to be so
accurate? Bull****. Making up your own rules as you go along again?

If your shoes are on
you wont make much of a path to ground.


After accusing me of giving being wrong, you state this whopper?

Bubba, go get your shoes on. Then go grab a hot wire in one hand and
touch a water faucet or the metal range with the other. You can wind
up dead with your shoes on. Also, only a fool would rely on shoes
as being adequate insulation. How about if they are damp?

First off, dip****, who walks around in their kitchen with wet shoes
besides some cupcake like you?
Second of all if I touch a cabinet of a refrigerator that happens to
have a bad ground while standing in my shoes in the kitchen Im NOT
going to be electrocuted you moron.


Bubba, A LOT of kitchens still have a metal edge on the countertop.
Not many in the big city - but still a lot elsewhere. That metal edge
CAN be grounded, and you CAN touch it and the fridge at the same time.
THEN you DO get a dangerous shock. Or you have a ?grounded" item in
your hand, and you bump the fridge. POW!!! It got ya. Or you are
washing dishes, and the frige is, like in many kitsn 3 ft from the
sink. You go to put a metal item in the dish drainer, next to the
fridge. While you still have a hold of it with your wet hand it
touches the fridge, (or some water has spilled over the drainer and
the pan touches the water that has also touched the fridge. Nasty
shock time.
Now, tell me how that statement is wrong again you dumb bonehead.
EE's. What a pile of useless **** heads. Thinking they have the
correct answer to everything while not even knowing the basics of
anything.


And I'm no bonehead EE


So anyways trader, this is payback for your jumping on my heart valve
post.

IF you would like to keep this **** up, have at it. I can have
fun with you all day.
Have a nice life

Glad you're havin' fun Bubba.
Bubba- Hide quoted text -

and as it appears, you do want to keep going so, "Game On!"

- Show quoted text -

Bubba, you're the one here who keeps following folks around. First
it was Ransley you were after, now it seems to be me. In the other
thread, last couple days, you had a little war with Hank. Simple
fact is, you can't seem to get along with anyone here. Seems more
often than not, when you enter a thread, a flame war soon errupts.
Gee, wonder why that is?

A war with Hank!? What, was it one or maybe 2 posts at the most there
trader? Make up some more horse **** liar.
Oh, and now you wish to be mother to everyone on the internet?
You're a loser of a **** ant trader. Get a life.
Is that your mommy calling you telling you to get off the computer
now?
Bubba

In article ,
Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to
the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

To meet the requirements of the applicable electrical code as specified
by the laws and regulations of the applicable district.


--
There are no stupid questions, but there are lots of stupid answers.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

Bubba wrote:
On Tue, 17 Feb 2009 14:21:40 -0800 (PST), wrote:

On Feb 17, 2:18 pm, Bubba wrote:
On Tue, 17 Feb 2009 10:09:08 -0800 (PST), wrote:
On Feb 17, 12:45 pm, Bubba wrote:
On Tue, 17 Feb 2009 06:21:14 -0800 (PST), wrote:
On Feb 16, 11:32 pm, Tony Hwang wrote:
Brian wrote:
If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????
Thanks
Brian
Hi, Neut.
*
L1 - @@@@@@@@@@@@*@@@@@@@@@@ - L2
*
ground------*
/////
Visually ground and neutral are physically tied together.
Between LO1 and L2 is 240V, between L1 or L2 and neutral is 120V.
Often this is called Edison circuit. G is for safety, N is part of
circuit, current loop. You see some electrical devices has 3 prong
plug and some has 2.
As someone else pointed out, the ground is there for safety.
But yet, you trader are going to point it out again. Why? As you
always do. Wanting to reinvent the wheel just like all you boring
EE's.
It's not
supposed to carry current, unless something goes wrong.
Oh, so its not supposed to carry current but it will? You sound like
the weather man. "Today there will be a 50% chance of rain".
That pretty much covers your ass.
For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted.
Incorrect trader........as usual. You would only have a chance of
being electrocuted if you made a path to ground.
Oh please, Bubba. If the case becomes hot, I said you COULD become
eletrocuted, which is absolutely true. I don't have to list every
condition that must be in place for that to occur.
OH wait a minute sweatheart. Now all of a sudden we dont have to be so
accurate? Bull****. Making up your own rules as you go along again?



If your shoes are on
you wont make much of a path to ground.
After accusing me of giving being wrong, you state this whopper?
Bubba, go get your shoes on. Then go grab a hot wire in one hand and
touch a water faucet or the metal range with the other. You can wind
up dead with your shoes on. Also, only a fool would rely on shoes
as being adequate insulation. How about if they are damp?
First off, dip****, who walks around in their kitchen with wet shoes
besides some cupcake like you?
Second of all if I touch a cabinet of a refrigerator that happens to
have a bad ground while standing in my shoes in the kitchen Im NOT
going to be electrocuted you moron.

I never said if you touch the cabinet of a refrigerator with just a
bad ground you will get electrocuted. This is what I said:

"As someone else pointed out, the ground is there for safety. It's
not
supposed to carry current, unless something goes wrong. For example,
if a hot wire inside your refrigerator shorted to the metal cabinet.
Without a ground, the case would become hot and you could be
electrocuted."

Everyone else understood that to be a true statement. This is an
example of why you have such a hard time here in the newsgroup. You
start a flame war over something that was either totally taken out of
context or never said in the first place.


It wouldnt matter what anyone said trader. Your brain interprets
anything and everything completly different than the rest of the human
race. That's what EE's tend to do. Deal with it. Its your problem.

Funny - whenever there is an argument it seems to be Bubba against the
world. Must be your brain works funny. Or maybe you just don't
understand the underlying science.

At least you provide humor for the day.

--
bud--

On Feb 17, 4:29*pm, Tom Horne wrote:
On Feb 16, 7:04*pm, Brian wrote:

If on a 220 single phase circuit the neutral and ground wires attach to the same buss bar in the
panel, why are they both needed ????

Thanks
Brian

Brian

First things first. *If it were in fact a 208,220,230,240 single phase
circuit it would have only three conductors.

In that case each of the two conductors that are neither bare
(uninsulated), *green, or white *would be the nominal phase voltage
relative to ground. *The third conductor is the Equipment Grounding
Conductor (EGC). *It might take the form of a bonded metal cable
jacket, cable tray, or a metallic raceway, or a wire much like the
other conductors of the circuit. *If it is in the form of a wire it
will be either bare (Uninsulated) or green in color or if it is
American Wire Gage (AWG) size four or larger it would be color coded
green at all accessible points. *The reason that the third conductor
can take the form of a metal enclosure around or supporting the
energized conductors is that it only carries current during a fault
condition. *Provided that the EGC was properly sized and installed it
will carry the fault current so well that the Over Current Protective
Device (OCPD) that is protecting the faulted current carrying
conductor will open and thus clear the fault.

If the circuit is a dual voltage circuit, such as 120/240 volt North
American residential service range, clothes dryer, or feeder circuit
then it will have both 120 volt and 240 volt loads supplied from the
same circuit. *In that case a forth conductor is run with the other
current carrying conductors. *That grounded current carrying
conductor; which is commonly called the neutral; will be white in
color or may be coded white at all accessible locations. *Under most
conditions of use it will be insulated and will not be supplied
through an OCPD.

Up until quite recently it was permissible to bond the chassis of
certain heavy appliances, such as stoves and clothes dryers, to the
neutral conductor that served the loads in that appliance. *Under some
narrower circumstances the neutral conductor could be bare but never
green. *Since certain uses, found mostly in residences supplied with
their own electrical service directly from the utility, the neutral
could be bare some confusion has developed as to whether it was an EGC
or a neutral. *The code however was always clear that certain
appliance chassis could be bonded to the neutral instead of having a
separate EGC. *The thinking was that these exception permitted
circuits were never smaller then number ten AWG and were nearly always
run from compression terminals to compression terminals so there was
little risk of an open or high resistance connection. *Likewise the
feeder circuits were also run from and to compression terminals.
Experience has shown that, although they are rare, high resistance and
open conductors do occur in these circuits. *Since the consequence of
such circuit failures was the energizing of the chassis of large
appliances or of the entire EGC system of separate buildings or feeder
supplied panels at 120 volts relative to ground this practice has now
been removed from the code and is only permissible in existing
installations that predate the respective code changes.

What was wrong with this technique is that it violates a basic
principle of safety engineering that holds that it should always take
two or more failures in the system, at least one of which is easily
recognizable as a condition that requires correction, to create an
immediate hazard to life or health. *With the four wire circuit any
open in the neutral causes noticeable undesired operation such as the
dryer not coming on or the stove's light and controls not working.
Most importantly the undesired operation does not occur simultaneously
with an immediate deadly hazard so that the users are unlikely to put
up with the condition long enough for a complimentary fault to occur
which would turn the situation hazardous.

I hope that is helpful
--
Tom Horne

Anyone who has ever stood barefooted on a concrete basement floor and
touched the chassis of an old radio made during an era when it was
common practice to ground the chassis to the neutral prong, knows well
that the chassis is still hot relative to ground. Modern devices
ground their chassis to the ground wire leaving no (or very little)
electrical potential between a concrete floor and the chassis itself.
If you touch a modern safety grounded device while standing barefooted
on your basement floor you will not receive the jolt commonly received
from old radios or TV's. There may be a few volts of potential there
(see definition of a "ground loop") but not enough to feel or cause
loss of life.