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Old 01-20-2012, 10:44 PM   #1
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electric grounding bar in main panel


can a ground wire and a neutral wire be connected under a single screw on the grounding bar in a main panel?
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Old 01-20-2012, 10:59 PM   #2
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electric grounding bar in main panel


I don't know much about electricity, but don't the ground and the white common end up there anyways?
I would think so, but I'm just guessing.
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Old 01-20-2012, 11:38 PM   #3
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electric grounding bar in main panel


My bad,i was having a senior moment!
I thought you were talking about bonding the neutral buss and ground buss to panel with same ground screw.
I normally stick the neutral and ground wires for each circuit directly above each other under seperate screws to make it easier to find them .
Although I did have a chief electrical inspector tell me once on a code violation repair job I was bidding on that it was legal to have more than 1 wire under each screw on a buss bar a couple years ago

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Old 01-21-2012, 12:16 AM   #4
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electric grounding bar in main panel


No. One neutral per termination. Most panels will allow 2 grounding wires under one terminal.
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Old 01-21-2012, 12:20 AM   #5
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electric grounding bar in main panel


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Originally Posted by steve gregory View Post
can a ground wire and a neutral wire be connected under a single screw on the grounding bar in a main panel?
In theory, the whole bar makes it one big connection. There is always that theory that if you connect the neutral and ground to one screw, that it could backfeed on either if there is a fault. Big clue here, the neutrals and grounds are on a common bar, so in reality, it does not matter.

But yes, if there is enough bar space, each wire should have its own screw on it, not shared with another common connection (ie ground or neutral).
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Old 01-21-2012, 12:39 AM   #6
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electric grounding bar in main panel


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Originally Posted by gregzoll
In theory, the whole bar makes it one big connection. There is always that theory that if you connect the neutral and ground to one screw, that it could backfeed on either if there is a fault. Big clue here, the neutrals and grounds are on a common bar, so in reality, it does not matter.

But yes, if there is enough bar space, each wire should have its own screw on it, not shared with another common connection (ie ground or neutral).
So I was kind of right? The place won't burn down if you do, but the inspectors say no...
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Old 01-21-2012, 12:53 AM   #7
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electric grounding bar in main panel


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So I was kind of right? The place won't burn down if you do, but the inspectors say no...
How did you come to that conclusion? Places would have burned down left and right for years, due to having grounds and neutrals sharing a common bus bar in a panel, when the panel is not used as a sub. Even as a sub, there are panels out there with grounds and neutrals on the same bus bar, and none of them have burnt to the ground.
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Old 01-21-2012, 04:29 AM   #8
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electric grounding bar in main panel


Neutral and grounding conductors can be connected to the same bus bar in service entrance panels.

They can NOT be connected together on the same terminal screw, however.

Neutral wires must be connected individually on their own terminal screw without anything else. Grounding wires may be combined together with other grounding wires if the terminal bar is listed for it.

The problem arises where a neutral wire can become loose, due to being combined with another wire in the same terminal. Neutral wires are current-carrying conductors, while bare grounding wires are not.

A loose current-carrying conductor can get hot, melt the insulation, and cause circuit failure. This has happened numerous times and as a result, the Code was updated to require single termination of those conductors.
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Old 01-21-2012, 10:04 AM   #9
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electric grounding bar in main panel


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Originally Posted by steve gregory View Post
can a ground wire and a neutral wire be connected under a single screw on the grounding bar in a main panel?
The answer is maybe .... but let me explain. Your question has some terminology clarification. The main panel needs to be the service equipment as Kbsparky has mentioned.. That is the place where the first means of disconnect for the service is located. It is also the only place where you bring the equipment grounding conductors ,grounded conductors and neutrals together and can be terminated to the same bonding bus ...ie ..neutral buss. Only one neutral or grounded conductor can be under one screw as already explained. Both grounding and grounded and neutrals can be connected to this bus(s) as there may be more than two neutral busses .... and in turn this bonds both to the utility grounded conductor or service neutral which is terminated to the neutral buss lug on one of the busses..
These busses will be installed or set on insulated stand offs and one of them will have the main bonding jumper which bonds the neutral buss(s) to the metal of the service equipment panel. If there are two neutral buses then a metal bar, strap, wire, or other listed means will be supplied by the manufacturer to bond the two neutral terminal busses together.

Now to get to the point. Your question asks can you connect a ground and a neutral wire together under the same screw on the grounding bar in the main panel. This is where the correct terminology becomes important. A grounding bar is not allowed to have neutral wires connected to it at all.

Neutral busses and Grounding bars are two different animals. Grounding bars are bonded to the panel metal and are separate from the neutral buss. The only thing that bonds them together at the service equipment, that is conductive, is the metal of the panel as the neutral buss will have the main bonding jumper.

The point being the only way for current to go from the grounding bar to the neutral buss is through or via the panel metal. The NEC does not allow neutral current or any objectionable current to use an enclosures metal to get back to the neutral buss and ultimately the source (transformer).

It does allow fault current to use 'bonded metal' such as the metal of an enclosure as it will only be present very briefly until the circuit breaker opens. Since the grounding wires (bare and green) for branch circuits and feeders.. ie ..equipment grounding conductors .. are the only wires intended to carry fault current then they may be terminated to a grounding bar.

So technically speaking using the correct terminology the answer to your question is .. NO.. you cannot land a neutral on a grounding bar at all.

Now if I have confused anyone I will add some diagrams if requested to show the differences.
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Old 01-21-2012, 04:46 PM   #10
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electric grounding bar in main panel


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The answer is maybe .... but let me explain. Your question has some terminology clarification. The main panel needs to be the service equipment as Kbsparky has mentioned.. That is the place where the first means of disconnect for the service is located. It is also the only place where you bring the equipment grounding conductors ,grounded conductors and neutrals together and can be terminated to the same bonding bus ...ie ..neutral buss. Only one neutral or grounded conductor can be under one screw as already explained. Both grounding and grounded and neutrals can be connected to this bus(s) as there may be more than two neutral busses .... and in turn this bonds both to the utility grounded conductor or service neutral which is terminated to the neutral buss lug on one of the busses..
These busses will be installed or set on insulated stand offs and one of them will have the main bonding jumper which bonds the neutral buss(s) to the metal of the service equipment panel. If there are two neutral buses then a metal bar, strap, wire, or other listed means will be supplied by the manufacturer to bond the two neutral terminal busses together.

Now to get to the point. Your question asks can you connect an ground and a neutral wire together under the same screw on the grounding bar in the main panel. This is where the correct terminology becomes important. A grounding bar is not allowed to have neutral wires connected to it at all.

Neutral busses and Grounding bars are two different animals. Grounding bars are bonded to the panel metal and are separate from the neutral buss. The only thing that bonds them together at the service equipment, that is conductive, is the metal of the panel as the neutral buss will have the main bonding jumper.

The point being the only way for current to go from the grounding bar to the neutral buss is through or via the panel metal. The NEC does not allow neutral current or any objectionable current to use an enclosures metal to get back to the neutral buss and ultimately the source (transformer).

It does allow fault current to use 'bonded metal' such as the metal of an enclosure as it will only be present very briefly until the circuit breaker opens. Since the grounding wires (bare and green) for branch circuits and feeders.. ie ..equipment grounding conductors .. are the only wires intended to carry fault current then they may be terminated to a grounding bar.

So technically speaking using the correct terminology the answer to your question is .. NO.. you cannot land a neutral on a grounding bar at all.

Now if I have confused anyone I will add some diagrams if requested to show the differences.
Last time I looked the neutral and ground busses were still bonded together in a main panel,theyre only seperated on a sub panel.
Im sure everybody knows that but I just wanted to clarify incase somebody doesnt know the differance
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Old 01-22-2012, 12:11 AM   #11
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electric grounding bar in main panel


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Last time I looked the neutral and ground busses were still bonded together in a main panel,theyre only seperated on a sub panel.
Im sure everybody knows that but I just wanted to clarify incase somebody doesnt know the differance
The diagram is representing a violation of NEC 200.2(B) as attached below

200.2 General. Grounded conductors shall comply with
200.2(A) and (B).
(A) Insulation. The grounded conductor, where insulated,
shall have insulation that is (1) suitable, other than color,
for any ungrounded conductor of the same circuit on circuits
of less than 1000 volts or impedance grounded neutral
systems of 1 kV and over, or (2) rated not less than
600 volts for solidly grounded neutral systems of 1 kV and
over as described in 250.184(A).
(B) Continuity. The continuity of a grounded conductor
shall not depend on a connection to a metallic enclosure,
raceway, or cable arm
or.


You missed the point entirely...... if you are saying that I was indicating that neutral and ground are separated in the main panel (service equipment).
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Old 01-22-2012, 12:15 AM   #12
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electric grounding bar in main panel


If a grounding bar is added in a panel it must only contain grounding conductors. You cannot add a neutral to a grounding buss and have current flowing on the metal enclosure.
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Old 01-22-2012, 01:05 AM   #13
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electric grounding bar in main panel


I was refering to factory installed equipment in main panel
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Old 01-22-2012, 02:20 AM   #14
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electric grounding bar in main panel


I'm not sure what that means as grounding bars can be factory installed, none the less it doesn't matter. I just wondered why you repeated in qoutes my entire reply and then made the comment you made......
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