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  #1  
Old 1/12/14, 10:45 PM
sappolloni's Avatar
sappolloni sappolloni is offline
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Default Panel grounding

Sorry if this question is elementary to some, I am still learning.
Attached is a picture of my electrical panel. The panel is a GE, and house built in 2005. The neutral bus bar is on the left, ground bar on the right. The green bonding screw is on the top bus bar on the ground side, and there is a metal bar attaching the two bars at the top. I do not see a stand alone ground wire, and on the outside of the house there is a grounding rod into the ground.

1.) How is my panel, and the ground bus bar grounded?

2.) Is the green bonding screw supposed to be on the ground side, I thought it was supposed to bond the neutral to the panel?
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  #2  
Old 1/12/14, 11:18 PM
Nathan E. Smith Nathan E. Smith is offline
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Default Re: Panel grounding

The first question: is this a main panel or sub panel?

Do you have a picture of the main? and can you take a picture of where the mains land in this panel?

That will help accurately answer your questions.

If the neutral side and ground side are connected (which they typically are) then the bonding screw is fine no matter which side it is on.

However if this is a sub panel than the neutrals and grounds should be separate which if the two bars are not connected than the "bonding screw" would simply be attaching the right bus bar to the can making it your grounding bar separate from the neutral bar.

Neutral to Ground bonding should only take place at one point in the electrical system and per code that should be at the "first point of disconnect" for the home. At all panels after that the neutrals and grounds need to be separate. We call this a "floating neutral"
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  #3  
Old 1/12/14, 11:26 PM
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sappolloni sappolloni is offline
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Default Re: Panel grounding

This is the Main panel. Also I see a few white wires going into breakers which I think is not allowed, and also At the top breakers I see they have a white wire going from the breaker to the bars? is that normal. And on two grounds there are multiple ground wires wrapped/twisted into the ground bar, I seen one was for the hvac, do larger appliances have grounds like that usually.

Last edited by sappolloni; 1/13/14 at 12:06 AM..
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  #4  
Old 1/13/14, 12:56 AM
Nathan E. Smith Nathan E. Smith is offline
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Default Re: Panel grounding

Yes the white wires are normal if they are arc fault or ground fault breakers.

After looking at the pictures again though... how is the panel being fed and where is it being fed from?
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  #5  
Old 1/13/14, 1:01 AM
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sappolloni sappolloni is offline
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Default Panel grounding

Overhead service. Wires coming in from the bottom. Three cables coming in from the bottom.
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  #6  
Old 1/13/14, 1:21 AM
Joel Engrahm Joel Engrahm is offline
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Default Panel grounding

The gray CB's appear to be either arc or GFCI with the curly white wire going to the neutral buss. It looks like they fed the two pole CB 's with a 2 wire non metallic wire as opposed to a three wire. White should only be used as a ground wire never as a hot or ungrounded wire.
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  #7  
Old 1/13/14, 4:45 AM
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Robert Meier Robert Meier is offline
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Default Re: Panel grounding

The white conductor in a cable assembly (NM cable) can be re-identified as an ungrounded conductor. There should be a turn of colored tape around the white conductor or some other marking to indicate that it is not a grounded conductor.

Quote:
200.7(C) Circuits of 50 Volts or More. The use of insulation
that is white or gray or that has three continuous white
stripes for other than a grounded conductor for circuits of
50 volts or more shall be permitted only as in (1) and (2).
(1) If part of a cable assembly that has the insulation per-
manently reidentified to indicate its use as an un-
grounded conductor by marking tape, painting, or other
effective means at its termination and at each location
where the conductor is visible and accessible. Identifi-
cation shall encircle the insulation and shall be a color
other than white, gray, or green. If used for single-pole,
3-way or 4-way switch loops, the reidentified conduc-
tor with white or gray insulation or three continuous
white stripes shall be used only for the supply to the
switch, but not as a return conductor from the switch to
the outlet.
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  #8  
Old 1/13/14, 10:07 AM
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Jeffrey R. Pope, CMI Jeffrey R. Pope, CMI is offline
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Default Re: Panel grounding

The only thing I don't see in this service panel is the grounding electrode conductor (GEC). Everything else looks good.

"White" wires to breakers are at arc-fault breakers, which is appropriate, and the bonding screw can be on either terminal since they are both bonded by a tie-bar.



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Old 1/13/14, 10:32 AM
Mike Arbusto Mike Arbusto is offline
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Default Re: Panel grounding

In *some* jurisdictions around here, I've seen the grounding electrode conductor (mostly solid 8 gauge wire inside a spiral armored jacket) attached at the meter socket, not at the service panel.
It must be a power company thing.
However, even though the socket is upstream from the service panel, the grounds and the neutrals are not separated at the panel in those cases.
The way it was explained to me, the meter is not considered service equipment, therefore the main panel downstream from it does not become a subpanel.
If you ask me, GEC should still be attached to the bar at the service panel, but again, based on what I was told, that would create "objectionable current" because now there are two conductor paths to the grounding electrode -- one at the meter, and one at the panel.
So, even though the PoCo's responsibility supposedly ends at the service point, they still get to dictate how to install meters and how to ground.
I am not sure whether the above applies to the OP's situation, but I wanted to mention my experience, in case it helps.
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  #10  
Old 1/13/14, 11:12 PM
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sappolloni sappolloni is offline
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Default Re: Panel grounding

Just curious, what if there was no tie bar on the bus bars, I would assume the neutral bar would have the bond screw, what about the ground bar, would that need to make any connection with neutral?
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  #11  
Old 1/14/14, 12:54 AM
Nathan E. Smith Nathan E. Smith is offline
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Default Re: Panel grounding

Objectionable current is one of those issues that is in constant debate and if you ask a dozen electricians to explain it you will probably get a dozen different answers...

However according to the NEC the neutral to earth bond should be at the "first point of disconnect" within a house.

The power company is responsible for their end and the electrical contractor is responsible at the panel end. I know of no instance (that doesn't mean it does not exist) where you are to "float" neutrals in your main panel or "first point of disconnect"

After looking back through the comments and reviewing the pics again I did see that white wires are being used as "hot" on the two pole breakers; and as Robert said they should be identified for the use.

Regarding the tie between neutral and ground bus... if this is the first panel in the system which would make it the first point of disconnect than the neutrals and grounds need to be bonded together so I would not remove the link. However if it was not there you could bond either side with the screw but then the neutral and ground bars would still need to be tied together in some fashion.

If this was a sub panel the link would be removed and the ground side only would be bonded to the can via the provided screw.
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Old 1/14/14, 4:56 AM
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Default Re: Panel grounding

A few comments, the GEC can be attached to the service neutral at any point in the system from the service point to the enclosure containing the service disconnect. This would include the meter enclosure or even the weatherhead on an overhead service. Some utilities, like those around here, do not allow the connection to be in the meter enclosure, in fact the connection needs to be accessible and many meter enclosures are locked so according to the NEC that connection point is prohibited.

On the line side of the service disconnect all metal parts are connected to the service neutral since there is no EGC. Services with metallic raceways between the meter enclosure and the service disconnect enclosure or panel will always have current flowing on the metallic service raceway. This is one of the few places where objectionable current is permitted and cannot be eliminated unless the two enclosures were connected with a non-metallic wiring method or PVC raceway.
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  #13  
Old 1/14/14, 8:16 AM
kwood kwood is offline
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Default Re: Panel grounding

Nathan & Robert! I know it is a challenge to make this simple for the Newbies. Good job explaining it.
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