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
Including the "main" CB box?
EMWTK
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
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
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.)
>|> 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.)
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.
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.
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
On Mon, 30 May 2005 07:22:35 GMT HorneTD wrote:
|> 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?
| 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.
I've seen a few that are short (counting each space as 1) on holes for neutral and ground connection. I also note that for Cutler-Hammer, there is no supplementary ground bar even available in their catalog with 42 holes (e.g. adding one so you can turn a panel into a subpanel). There seems to be some assumption of doubling up, as the bars that are available list their hole sizes as being capable of 2 or even 3 wires when the size gets down to 14 or 12.
| 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.
When you have a top fed panel and running branch circuits back up through the top knockouts, it can get crowed up there. And with a live feed coming in up there, it's not enough to just off the main breaker.
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
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."
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.
-- Tom Horne
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.
=AEoy
On Mon, 30 May 2005 18:03:10 -0400 John Gilmer wrote: | | . |>
|> 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.
There are 3 possibly semantics:
The words stated were not specific enough to precisely identify all of these semantics.
| 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."
Of course. This explains why neutrals must never share with a wire from any _other_ circuit. But, this risk is not present if the neutral shares with ground on the very _same_ circuit ... any more so that is the risk of someone just pulling out the neutral of a live circuit (e.g. traced the wire down wrong).
Anyway, I'm looking for wording that is specific enough that shows who composed that wording absolutely considered case #3, as opposed to someone who only considered cases #1 and #2. It is possible for someone considers only #1 and #2 to come up with the very same wording as someone who also considered case #3, but that would not make it clear that case #3 was being considered. So under the current wording, it is simply unclear whether case #3 is intended to be prohibited (for some different reason not yet stated), or was not considered. If #3 is intended to be prohibited, I do want to know the hazard such a prohibition intends to protect from.
Whether we like it or not, semantics and words do play a critical role here. The NEC is full of subtle wording that can differentiate between whether a method is permitted, prohibited, excluded, included, or just not considered. Engineers as a group tend to be poor at good wording (not that lawyers are any better), though there will be some exceptions that stand out. While it does appear to me that the NEC was written by those with an above average ability to compose good wording, it is also not perfect at this.
| 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.
How is it that this thermal cycling risk would be any worse when the neutral shares a hole with one ground wire that is part of the same branch circuit, as compared to the risk of a neutral coming loose when it has a hole all to itself?
Yep, that's the "no, no."
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.
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.
What article? Ed
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