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Two Ground Bars

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Dale Hayes

Senior Member
We will be installing two ground bars onto an enclosure back panel. One of the ground bars will be at the top right corner of the back panel and it will be used for line side grounding. The other ground bar will be at the bottom middle of the back panel and will be used for load side grounding. Both ground bars are attached to the steel back panel. Is the steel back panel a sufficient ground path between the two ground bars or do I need to run a ground wire connection between the two ground bars?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
May I ask why you are separating the grounds to begin with. If they are connected together in the end why the need to separate the grounds?

I believe the can is a sufficient path however I prefer a short piece of wire connecting the 2 bars.
 

Dale Hayes

Senior Member
Why Two Ground Bars?

Why Two Ground Bars?

One ground bar (top left) is the ground for the line side of a 400A fused disconnect. The ground connection is 3Ga.

The other ground bar (bottom middle of back panel) is for (7) 60Amp resistive circuits. The (7) ground connections for these circuits are 10Ga.

Why two ground bars?

We want to keep the (7) ground connections as close to the (7) circuit load connections as possible - if not, then we have to strip back the (7) 3 conductor with ground cables back 72" so thet the ground wire will reach the ground bar at the top left of the back panel.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
While the panel cannot serve as a grounded-conductor pathway, it can serve as the EGC pathway.
 

brian john

Senior Member
Location
Leesburg, VA
We will be installing two ground bars onto an enclosure back panel. One of the ground bars will be at the top right corner of the back panel and it will be used for line side grounding. The other ground bar will be at the bottom middle of the back panel and will be used for load side grounding. Both ground bars are attached to the steel back panel. Is the steel back panel a sufficient ground path between the two ground bars or do I need to run a ground wire connection between the two ground bars?

It seems like the old HooDoo VooDoo black magic of grounding is at work?
 

Dale Hayes

Senior Member
Two Ground Bars (Continued)

Two Ground Bars (Continued)

The system voltage is 480Volt, 3phase input with ground.

The (2) ground bars are for Equipment Grounding Conductors (ECG's).
 

RUWired

Senior Member
Location
Pa.
If you take a look at 409.60, the last sentence says an equipment grounding conductor shall be connected to an equipment grounding point in each single section and to every section if multiple sections. I don't see any exceptions for multiple equipment grounding points.One could interpret that if a ground bar is installed, an egc shall be connected to. Just
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.

Rick
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Picture this. I run EMT to enclose the feeder for this panel and use the EMT as my EGC as per 250.118 and 358.60. My connectors meet the requirements of 250.97 ex. 3. Therefore I have no wire EGC. Compliant? Sure it is.

Now I add a ground bar to the panel. The enclosure is functioning in the same manner as it would in the OP install.

Or, what Larry said.
 

tom baker

First Chief Moderator & NEC Expert
Staff member
Location
Bremerton, Washington
Occupation
Master Electrician
I commonly see this in control panels where the metal enclosure is used for the grounding path when EG bars are bonded to it. But these are enclosures per UL 408A.
However, it would appear to be acceptable.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Although it is something that is done often, and I know of no negative results, officially I wonder if adding a ground bar in a panel other than the manufacturer prescribed bar in the prescribed location would be an alteration of a UL listed panel.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Although it is something that is done often, and I know of no negative results, officially I wonder if adding a ground bar in a panel other than the manufacturer prescribed bar in the prescribed location would be an alteration of a UL listed panel.

You mean like drilling mounting holes or making your own knock-out?:roll:
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
You mean like drilling mounting holes or making your own knock-out?:roll:

really never thought about that... probably does also.....
it's not something I ever gave thought to or investigated....
I see a slight difference in a grounding means and a knockout, but both are probably an "alteration".
Do you know the "official' stance ?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Although it is something that is done often, and I know of no negative results, officially I wonder if adding a ground bar in a panel other than the manufacturer prescribed bar in the prescribed location would be an alteration of a UL listed panel.
Same question could apply to installing a grounding bus into a box when there is no manufacturer's part available.

I've used generic boxes for many different purposes, where I needed to bond one, two, or as many as 24 EGC's.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
as have I. I see no problem with the other, but if there was accident/injury involved wonder where the "expert" testimony would lead on adding the ground bar ?
 

RUWired

Senior Member
Location
Pa.
Picture this. I run EMT to enclose the feeder for this panel and use the EMT as my EGC as per 250.118 and 358.60. My connectors meet the requirements of 250.97 ex. 3. Therefore I have no wire EGC. Compliant? Sure it is.

Now I add a ground bar to the panel. The enclosure is functioning in the same manner as it would in the OP install.

Or, what Larry said.


Chris, IMO, you would have to install a grounding bushing and an EGC to the ground bar according to 408.60.(and also to the additional ground bar). It says what it says or what i think it says.
nec2008 said:
409.60 Grounding.
Multisection industrial control panels shall be bonded together with an equipment grounding conductor or an equivalent equipment grounding bus sized in accordance with Table 250.122.

Equipment grounding conductors shall be connected to this equipment grounding bus or to an equipment grounding termination point provided in a single-section industrial control panel.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Rick, I fail to see where the OP mentioned anything about a 409 install. I believe the example I gave would be 408.40 compliant, thus shedding some light on the question at hand.
 

RUWired

Senior Member
Location
Pa.
Rick, I fail to see where the OP mentioned anything about a 409 install. I believe the example I gave would be 408.40 compliant, thus shedding some light on the question at hand.

Chris i pictured industrial control panel, maybe its not.
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We will be installing two ground bars onto an enclosure back panel. One of the ground bars will be at the top right corner of the back panel and it will be used for line side grounding. The other ground bar will be at the bottom middle of the back panel and will be used for load side grounding. Both ground bars are attached to the steel back panel. Is the steel back panel a sufficient ground path between the two ground bars or do I need to run a ground wire connection between the two ground bars?
 
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