Square D 200 A Main Pannel

[h1h2h3]

Just performed a 200 A service upgrade....first one on my own with my license . In any case, the customer wanted a square D Homeline Panel. This particular panel had an odd setup compared to the Murray panels that I'm used to using. Above the main disconnect, were the two terminals for the ungrounded conductors. In between these two terminals, was the terminal for the grounded conductor and directly adjacent to the this terminal (immediately to the right of it (in fact they were cast together)) was a smaller terminal which i can only imagine was for the Grounding Electrode Conductor. Installed on either side of the panel were ground bars. I installed the grounded conductor and G.E.C. in the appropriate terminals and bonded the neutral/ground bus and bonding strip to the cabinet itself with the green bonding screw. My question is.....do the ground bars on either side of the panel require additional wiring to effectively ground the egc's? (such as running the equivalent of the largest sized egc to that ground bar from the neutral/ground bus........as you would if you were installing a ground bar in say a separate trough)....does the use of the bonding screw make this unnecessary? Also, Does anyone know why square d uses this set up? Is it so the panel can be readily used as a sub-panel?

Any insight is always appreciated

 

[Dennis Alwon]

I don't know Sq. D panels but I am quite certain that the ground bars/neutral bars are connected to the neutral via a bus bar or something. I have never had to add extra wire to a panel ground/neutral bar. If this is the main disconnect then all the egc's, neutrals and GEC's should all be connected together.

 

[augie47]

The bond screw will serve as the bonding jumper for your equipment grounds.
Note that 240.24 dictates that the grounding electrode conductor shall connect to the grounded conductor. That small lug you describe is indeed there for that purpose.
A case can be made that by connecting your GEC to the equipment ground bar you have not met the requirement of 250.24 as any current
directed to the grounding electrode must now pass thru the metal enclosure (by way of the bond screw)

After reading Dennis' reply and thinking about SquareD panels I believe the ground bars you are talking about are the ones internally connected to the neutral and isolated from the can. That being the case, my statement above is incorrect.
If they are equipment ground bars secured to the enclosure itself (normally an "add-on") then the statement is correct.

 

[electricmanscott]

The bond screw is adequate and all that is necessary.

I have met more than one inspector that "wants to see" a jumper between those bars. I usually just ignore them. :roll:

 

[Dennis Alwon]

It sounds like there are ground bars on either side of the panel. I would hope that they are connected together if it is a main panel. If not the screw will only bond the can and cannot be used as a means to connect to the other bar if neutrals are connected to it. I just want to be clear about this. Thus two bond screws do not make a connection to each other when neutrals are involved on both bars. art. 408.40

 

[augie47]

Dennis, If I recall correctly Sqaure D has two bars (one each side) isolated and internally connected with a partially non-exposed tie bar which also has the line neutral lugs.
Other than for a service panel, an equipmemnt ground bar must be added for EGC.
(Unlike the Murray and GE panels where the tie bar between the two
sides can be lifted)

 

[Dennis Alwon]

Dennis, If I recall correctly Sqaure D has two bars (one each side) isolated and internally connected with a partially non-exposed tie bar which also has the line neutral lugs.
Other than for a service panel, an equipmemnt ground bar must be added for EGC.
(Unlike the Murray and GE panels where the tie bar between the two
sides can be lifted)

I assumed that but I wanted to make sure the OP got it right.

 

[LarryFine]

Just to make sure we have it straight, the green bonding screw ties the cabinet, and any EGC's landed directly on it, to the neutral.

I have used that second, smaller hole cast next to the main lug to supply a sub-panel's neutral conductor. it came in very handy.

If there are seprate, isolated-from-the-cabinet buses, these are already tied to the main neutral lug. The screw jumps that isolation.

It's my understanding that the electrode connections can't use the cabinet as part of their pathway, so must land on the neutral bus.

As long as the main disco is in this panel, use of the cabinet-mounted buses is optional. I usually take them out and save them.


Any questions?

 

[A/A Fuel GTX]

I usually take them out and save them.

Me too.......IMHO, those bars are there if a 4 wire feeder is used and the green screw is not installed thus isolating the neutral from the EGC. If the panel is being used as service equipment, the neutral bars that run parallel to the breakers are more than adequate for the grounded/EGC's.

 

[kwired]

We need OP to clarify if he is describing the insulated bars that are right next to the breaker pan (bonded to enclosure only if bonding screw is installed) or the equipment ground bars that are usually located near the side walls of the cabinet and bolted directly to the back wall of the cabinet.

Homeline panels that are sold to big box stores often have equipment ground bars pre-installed. If purchasing them from a supply house they often are not even included in a main breaker panel.

I don't know why OP thinks this is rare I have seen others with similar design, Cutler Hammer, Siemens, GE. Additional equipment ground bar is not always supplied but is available and has a place intended for it to be installed.