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Neutral and Earth Ground Question

P

Peter

I have a question about house wiring.

In my house, our earth ground (green) goes to a metal strip in the circuit
breaker box and then out to a 10ft pole in the ground I believe?

Other people are telling me that all the green wires should be tied to
neutral in the fuse box.

Is this true and/or where do I find out how the latest house wiring
codes??? As in, what catagory would I search for???


Thanks
 
S

SQLit

Peter said:
I have a question about house wiring.

In my house, our earth ground (green) goes to a metal strip in the circuit
breaker box and then out to a 10ft pole in the ground I believe?

Other people are telling me that all the green wires should be tied to
neutral in the fuse box.

Is this true and/or where do I find out how the latest house wiring
codes??? As in, what catagory would I search for???


Thanks

Your looking for Services, article 230 in the NEC.

Ground rods installed for residential are usually 8 feet long.

Grounds and neutrals are always tied together at the service, (meter
location). And separated every where else. Your vague as to the exact
installation so definite answers are impossible.

Assumption is that you reside in North America
 
J

John Gilmer

Grounds and neutrals are always tied together at the service, (meter
location). And separated every where else.

Including the "main" CB box?

EMWTK
 
F

Fred

The neutral conductor is grounded only once and at the main service entrance
only..

In Canada the neutral bar in a "service entrance panel" is grounded to the
panel via a brass screw that bonds the neutral bar to the panel steel
enclosure. The main ground conductor is also bonded to the panel metal
enclosure. This brass screw in effect bonds the neutral bar to the main
ground conductor. This screw is to be removed on sub panels connected to
the main panel.

Fred
 
B

Bob Weiss

John said:
Including the "main" CB box?

EMWTK

Ground and neutral are bonded at the "main service disconnect". In
most residential services, that is the main breaker in the panel, so the
neutral is grounded inside the main panel. If the service includes an
outdoor main disconnect switch, the neutral is bonded there, and kept
separated downstream.


Bob Weiss N2IXK
 
J

John Gilmer

Ground and neutral are bonded at the "main service disconnect". In
most residential services, that is the main breaker in the panel, so the
neutral is grounded inside the main panel. If the service includes an
outdoor main disconnect switch, the neutral is bonded there, and kept
separated downstream.

IOW: In your typical service CB box with a BIG breaker at the top, there
isn't any difference between GROUND and NEUTRAL.

(Well, maybe a little. If you run short of screws for grounds/neutrals you
should double up on the groups but not on the neutrals.)
 
J

John Gilmer

The US National Electric Code specifically forbids a neutral being
terminated with another conductor in the same termination within a
panel. That rules out sharing a terminal with the Equipment Grounding
(Bonding) Conductor.

True. It's means that neutral and ground aren't under the same screw or in
the same "hole." But otherwise, there isn't a separate buss for ground and
neutral.
 
D

daestrom

HorneTD said:
The US National Electric Code specifically forbids a neutral being
terminated with another conductor in the same termination within a panel.
That rules out sharing a terminal with the Equipment Grounding (Bonding)
Conductor.

Maybe it's just me, but all the service panels I've been in (admittedly only
a few), there are exactly as many holes in the neutral bar as there is in
the ground-bus bar, and that number is more than the number of 'slots' for
circuit breakers. So unless you have two circuits coming from every
breaker, finding an empty hole for the neutral (in the neutral bus) and an
empty hole in the ground bus (even when neutral and ground are not bonded
such as a sub-panel) hasn't been all that much of a problem.

The only problem I've ever had is when some jerk runs a whole series of
circuits right over the top of a section of neutral bus so you can't get to
the holes. But that's a different story.

daestrom
 
E

ehsjr

|> I recall a question asked a while back that was never answered. Can the
|> neutral and the ground of the _same_ branch circuit be put together in
|> one hole with no other wires of any other circuit in that hole?
|>
|> The greatest risk I understand there to be of doubling up neutrals is that
|> during maintenance of one circuit, this can result in the neutral of the
|> other circuit left disconnected or loose. For 2-wire circuits, this can
|> result in hot circuit that does not function. For 3-wire circuits with a
|> shared neutral, that circuit can have all the problems of an open neutral.
|>
|> IWSTM that with a neutral sharing the hole with a ground for the same exact
|> circuit, this risk would not be present.
|>
|> OTOH, I would be supportive of a code rule that requires all neutrals in
|> one bus and all grounds in another bus, as would be required in a subpanel,
|> even for a main panel (just bonded together in a main). The reason is that
|> it allows an easier insertion of an upstream main (which will then have the
|> neutral-ground bond) and removal of the bond in the panel that is demoted
|> to being a subpanel, without having to juggle the wiring. My theory is if
|> a doubling of neutrals exposes a risk of mistake, juggling grounds and
|> neutrals in a panel being converted from main to sub is as much, if not
|> more, of a risk.
|>
|> But personally, I think the Darwin rule serves well.
|>
|
| The US National Electric Code specifically forbids a neutral being
| terminated with another conductor in the same termination within a
| panel. That rules out sharing a terminal with the Equipment Grounding
| (Bonding) Conductor.

The US National Electric Code also is a blunt instrument in terms of
covering technical issues with proper procedures and methods. What
would be the issue in this case that would make people not want to
allow an exception so that neutral and EGC of the same circuit can
share the same hole?


If the bus bar is listed for the use (2 wires in the same hole)
it's not a problem, so the "exception" is already built in. As
far as solving the problem of not enough holes, just add another
bus bar.

Ed
 
J

John Gilmer

..
The US National Electric Code also is a blunt instrument in terms of
covering technical issues with proper procedures and methods. What
would be the issue in this case that would make people not want to
allow an exception so that neutral and EGC of the same circuit can
share the same hole?

Didn't someone already cite the NEC words that say that NEUTRALs don't
"share." "Grounds" can share. I suspect that in many panels, the "next
time" you modify or add a circuit, you consider "curing" these violations.

Frankly, if you are running short of screws, you can alway "multiplex" your
grounds by any one of a number of approved ways. If neutral and ground are
already firmlybonded to the panel case, legal grounding can be just by
bonding to the metal of the panel inclosure.

A short term interruption of "ground" should not hurt anything whereas a
short term interruption of neutral mgiht easily damage or destroy lots of
expensive "stuff."
 
T

Takoma Park Volunteer Fire Department Postmaster

|> I recall a question asked a while back that was never answered. Can the
|> neutral and the ground of the _same_ branch circuit be put together in
|> one hole with no other wires of any other circuit in that hole?
|>
|> The greatest risk I understand there to be of doubling up neutrals is that
|> during maintenance of one circuit, this can result in the neutral of the
|> other circuit left disconnected or loose. For 2-wire circuits, this can
|> result in hot circuit that does not function. For 3-wire circuits with a
|> shared neutral, that circuit can have all the problems of an open neutral.
|>
|> IWSTM that with a neutral sharing the hole with a ground for the same exact
|> circuit, this risk would not be present.
|>
|> OTOH, I would be supportive of a code rule that requires all neutrals in
|> one bus and all grounds in another bus, as would be required in a subpanel,
|> even for a main panel (just bonded together in a main). The reason is that
|> it allows an easier insertion of an upstream main (which will then have the
|> neutral-ground bond) and removal of the bond in the panel that is demoted
|> to being a subpanel, without having to juggle the wiring. My theory is if
|> a doubling of neutrals exposes a risk of mistake, juggling grounds and
|> neutrals in a panel being converted from main to sub is as much, if not
|> more, of a risk.
|>
|> But personally, I think the Darwin rule serves well.
|>
|
| The US National Electric Code specifically forbids a neutral being
| terminated with another conductor in the same termination within a
| panel. That rules out sharing a terminal with the Equipment Grounding
| (Bonding) Conductor.

The US National Electric Code also is a blunt instrument in terms of
covering technical issues with proper procedures and methods. What
would be the issue in this case that would make people not want to
allow an exception so that neutral and EGC of the same circuit can
share the same hole?
The fact that the neutral carries current and is therefore subjected to
thermal cycling. If not terminated in individual terminals the
connection will loosen if the thermal cycling is not the same and of
course it never would be.
 
R

Roy Q.T.

From: Peter
I have a question about house wiring.
In my house, our earth ground (green) goes to a metal strip in the
circuit breaker box and then out to a 10ft pole in the ground I believe?
Other people are telling me that all the green wires should be tied to
neutral in the fuse box.
Is this true and/or where do I find out how the latest house wiring
codes??? As in, what catagory would I search for???
Thanks

------------->

The neutral and grounding busses in your house, by your description are
correct., people assume differing positions on grounding issues but the
NEC is speciic on the matter., and the only place required to have the
neutral and ground tied together as you say is at the Meter/Disconnect.

If you have 2 isolated busses in your breaker panel (1)with the green
wires & (1) with the white wires ) count yourself lucky you have a truly
Bonded & Grounded Panel.

You can find more about this subject if you look up " Bonding " in your
search engine.

In Excisting Bonded Residential Panels the Bonding & Neutral Buss Bars "
Do Not Require Jumping " nor being connected to each other in any way ~
that has already been negotiated at the meter panel or service
disconnect panel.

®oy
 
J

John Gilmer

There are 3 possibly semantics:

1. Neutral sharing with neutral ... obviously of a different circuit.

Yep, that's the "no, no."
2. Ground sharing with ground ... obviously of a different circuit.

But this happens "all the time." (Well, maybe not "all the time," but
close. If a box is large enough there is no restriction on having more
than one circuit pass through. But it's clear that all the GROUNDS are
bonded together, especially if it is a metal box.
3. Neutral sharing with ground ... could be the same circuit.

That has potential problems in that the "ground" and "neutral" of a circuit
may easily remain connected while both are connected from the
"ground/neutral." IF the corresponding HOT wire remains connected, you can
easily have a section of "ground" that's actually HOT.
 
E

ehsjr

HorneTD said:
The US National Electric Code specifically forbids a neutral being
terminated with another conductor in the same termination within a
panel. That rules out sharing a terminal with the Equipment Grounding
(Bonding) Conductor.

What article?
Ed
 
J

John Gilmer

|> 3. Neutral sharing with ground ... could be the same circuit.
|
| That has potential problems in that the "ground" and "neutral" of a circuit
| may easily remain connected while both are connected from the
| "ground/neutral." IF the corresponding HOT wire remains connected, you can
| easily have a section of "ground" that's actually HOT.

Huh? You're saying that a problem can exist because ground and neutral
would remain connected while a hot wire remains connected?

They can remain connect to EACH OTHER but not connecto to neutral/ground.
That makes
no sense because having all wire remain connected is a GOOD condition,
not a bad one.

They make spelling checkers. But maybe you need a wording checker.
Maybe.
http://ka9wgn.ham.org/ |
--------------------------------------------------------------------------
---
 
E

ehsjr

HorneTD said:
408.21 Grounded Conductor Terminations.
Each grounded conductor shall terminate within the panelboard in an
individual terminal that is not also used for another conductor.

Thanks!
 
T

Takoma Park Volunteer Fire Department Postmaster

| [email protected] wrote:
|> | [email protected] wrote:
|> |>
|> |> | Mount a four hole lug of appropriate size on an insulating stand off,
|> |> | bug the three conductors onto a short pigtail off of the breaker using
|> |> | spit bolts or insulating displacing connectors as appropriate, use an
|> |> | insulated multi tap block to join the four conductors to the jumper from
|> |> | the breaker... There is always a code compliant way to do it. You just
|> |> | have to invest the time or the money in hired expertise to find out what
|> |> | that way is.
|> |>
|> |> If I would approve of things like pigtails and splices, I'd just run some
|> |> 600 kcmil from the main breaker down a raceway and splice off each of the
|> |> 4/0 feeds into the 3 panels they go to. But my intention is to absolutely
|> |> avoid splicing (having seen the mess when they fail). I believe the risk
|> |> is less by just stranding the 4/0 into 2 adjacent holes on the same lug.
|> |> Or can you show me code that says not to split stranded wire into two holes?
|> |> I'm not convinced about the "fracturing" issue since this will involve less
|> |> mechanical stress on the wire than typical wire bending that takes place in
|> |> typical panels, especially if I use the larger box that would be needed to
|> |> put all those pigtails below the breaker.
|> |>
|> |
|> | 110.3 Examination, Identification, Installation, and Use of Equipment.
|> | (B) Installation and Use. Listed or labeled equipment shall be installed
|> | and used in accordance with any instructions included in the listing or
|> | labeling.
|>
|> So basically, you can't figure out a better way to do it.
|>
|> At this point I will now ignore all followups that do not have a constructive
|> solution not involving splices, pigtails, or other unsecured connections.
|>
|
| Undoubtedly because they are code compliant and your method is not.
| Would you mine explaining how an insulated terminal block is an
| unsecured connection?

Your description of why not to mix current carrying conductors in the
same hole ...


| It is the thermal cycling of the current carrying grounded conductor
| (neutral) that makes having it in the same termination as the Equipment
| Grounding (bonding) Conductor (EGC) an unsafe practice electrically.
| There has yet to be devised a terminal that can use one pressure
| producing part to maintain good electrical contact with two conductors
| that are thermally cycling at different rates and times. If you look at
| the breakers that are listed to hold two separate conductors you will
| see that the conductors are separate from each other and the screw has a
| pressure washer under its head. The addition of the pressure washer or
| plate allows solid contact between both conductors and the plate into
| which the screw is threaded. The pressure washer will flex sufficiently
| to permit unequal thermal cycling without the connection failing.
|
| In thirty years of electric work I have seen many connection failures
| caused by improper torquing of connections and by using a single
| terminal to terminate multiple conductors. The reason that it is safe
| to use a single terminal to terminate multiple EGCs is that they do not
| carry current during normal operation and they are not subjected to
| repeated thermal cycling.

... would just as readily apply to phase conductors as well as the
neutral. If you have 2 or more different loads (hence different
thermal cycling characteristics) fed by different conductors in the
same hole, the same problem will occur. A pigtail is thus like that.
Maybe this is why pigtails have failed. Your earlier post further
reinforces my intent to avoid all pigtails with 3 or more conductors
(those with 2 will be avoided as well, but your post doesn't really
reinforce my intent against those).

But I hardly would consider putting a 600 kcmil and 3x 4/0 together
on the same pigtail. Maybe cad-welded ... maybe.

As for a terminal block, how is it any different than a lug on a circuit
breaker, other than taking up even more space. How is it that a terminal
lug would be safe enough to be listed as a terminal block and not as part
of a circuit breaker?

A friend of mine is a metal machinist. Perhaps I'll just have the exact
lug needed manufactured for me.

BTW, did you know that a common practice when 2 more more panels are
needed in parallel is to put 2 wires in the lugs, one coming from the
service entrance metal, and the other going to the 2nd panel? What I
wonder is if you would cringe at that? I would. Yet it is common,
and has the same issue you explained before. But I will be avoiding
such a thing.

Phil
I just reread your reply and I'm going to have to ask you when I
suggested trying to "pig tail" several large conductors into a single
connection? You say you have seen this done. What materials were used
to do it because I cannot imagine how that could be done.
 
B

Ben Miller

I recall a question asked a while back that was never answered. Can the
neutral and the ground of the _same_ branch circuit be put together in
one hole with no other wires of any other circuit in that hole?

Think about what happens if those two wires are removed together. You would
disconnect the grounded conductor and the equipment grounding conductor, but
the circuit would still be connected to the ungrounded side of the line.
This would be extremely dangerous if there was any leakage current or fault.

Ben Miller
 
B

Ben Miller

At this point, though, I think I will have the correct lug manufactured.
I'm sure I can get it made in tinned solid copper.

And I assume you will have an appropriate listing agency test and label
them, so they are code compliant? Why not use the lugs that are commercially
available, designed for the purpose, and verified by UL, as Tom Horne has
suggested?

Ben Miller
 
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