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matrix733 11-28-2007 10:12 AM

Bonding Ground and Neutral
 
Hello fellows, I have a 100amp square D main panel with a 100amp main breaker installed. I need to know the proper way to bond the Ground to Neutral.

Do I need to run a green wire from the ground bus and attach it to the metal case with the green screw or should it be connected to the Neutral bus from the ground bar.

I have a small diagram of my setup below, there is a spot on the right for another ground bar but thats not really needed.

http://img253.imageshack.us/img253/8...inpanelfn3.jpg

hope I don't sound confusing.


From what I have read (correct me if am wrong) if there is no seperate disconnect other than the main breaker (in the main panel) the neutral and ground should be bonded?

J. V. 11-28-2007 10:37 AM

Assuming you met all the criteria regarding panel installations, you must bond the EGC terminal bar to the neutral terminal bar.
This is only done at the main service panel, not in a sub panel.
Look and see if you have two terminal strips running vertically on each side. If this is a new panel these two strips will have a factory installed bar that connects them. If this is the case, just leave the bar in place and use one side for neutrals and the other for EGC's. This looks better than having bares and greens on the same strip.

If this is not a MAIN SERVICE panel, disregard all the statements I have made and let us know more.

jbfan 11-28-2007 11:09 AM

The netural should have a place for you to install the bonding screw.
That would be the green screw you are talking about.
Is this panel fed with 3 wires or 4?

matrix733 11-28-2007 12:04 PM

Thanks for the reply fellows. Its a main panel, not a sub. The panel has two 120v conected to each hot bus and then one neutral wire connected to the vertical neutral bus bars.

The ground bus pictured was not installed from factory, a matter of fact i have yet to install it but bought it in case its needed.


Let me see if I understand this correctly, I can run the ground wire from the ground rod directly to the neutral bus bar and install it with the green bonding screw.?

I can then have neutral and ground wires on either side of the neutral bus bars but I should try and keep ground on one side for a neater appearance?

If more space is needed (doubt I will need more) I can install the ground bar, run the ground wire from ground rod to the ground bus, then a green wire from the ground bus to the neutral bus (installed with green screw)?


My meter is pulled by the way......


Thanks for your help.

HouseHelper 11-28-2007 12:09 PM

If this is a new panel, it should have come with a green bonding screw that mounts in the bar that connects the two neutral buses. This bonds the enclosure to the bars. If you then mount an additional ground bar on the panel using the provided machine screws, it is now also bonded to the enclosure, you do not need to do anything else.

matrix733 11-28-2007 01:50 PM

ok, the mud is clearing up now (i think) lol. The bonding screw bonds the neutral/ground buses to the metal case and since this is also where the ground wire (from ground rod) connects, the entire metal case/neutral and any additional ground bar attached to the metal case is now grounded.


Therefore, no extra ground wire needs to be ran for the additional ground bars connected to the metal case.



Thanks, all the help much appreciated.

Stubbie 11-28-2007 02:22 PM

1 Attachment(s)
Hello Matrix


Quote:

Let me see if I understand this correctly, I can run the ground wire from the ground rod directly to the neutral bus bar and install it with the green bonding screw.?
No not quite right....househelper clarified but I'll jump in to try to help. The gec (you call it the ground wire) is ran to any hole you want in either of the two bars that will accept (size wise) the copper gec to the ground rod. This is usually a #6 awg solid copper wire.

The green screw is the bonding means for the metal of the panel to be bonded to the neutral bar. It will have a hole in the neutral bar or the strap that joins the two neutral bars that it goes thru and it threads into the panel metal back bonding the two together.

Quote:

I can then have neutral and ground wires on either side of the neutral bus bars but I should try and keep ground on one side for a neater appearance?
Well I suppose some may think that but the square d panels were never meant for that to be the case. They did this so you could keep both neutrals and grounds oriented to the breakers they serve. So you would have neutrals and grounds connected to each bar on both sides for ease of wiring. You can only put one neutral under a compression screw in the bar but you can put 2 ground wires of the same size under one screw.

Quote:

If more space is needed (doubt I will need more) I can install the ground bar, run the ground wire from ground rod to the ground bus, then a green wire from the ground bus to the neutral bus (installed with green screw)?
No... as househelper said the ground bar simply mounts in the panel back in the factory made holes to will be bonded to the neutral bar because the green screw has been installed up on the neutral bar or joining metal strap which is threaded into the metal of the panel back. The green screw bonds the metal of the panel to the neutral bar, so since you mount the ground bar to the metal of the panel it is automatically bonded with the neutral bar via the green screw.

Here is an image of a square d panel and the green screw we are talking about it may be similar in your panel....nothing is fastened to any thing with it. It simply bonds the neutral bar to the metal of the panel so fault current can get to the service neutral follow it to the transformer (source) so a breaker will trip in a fault condition.


Notice neutrals and grounds on the same bar. Your panel may not be exactly set up like this but you should get the idea... now... with the green screw. They usually tape it in the panel in a package for you to remove and install it in the panel when your using the panel as a main service rated panel.

Stubbie 11-28-2007 02:32 PM

You also need to have a grounding electrode conductor ran to a water pipe if your water pipes are metal coming into the house. This is the big copper wire you see in the image left of the service neutral.


I also see you picked up on the bonding thing with the green screw....:)

matrix733 11-28-2007 04:01 PM

got it, thanks much, you da man:thumbup:

Stubbie 11-28-2007 05:42 PM

1 Attachment(s)
Matrix what I like to do with split neutral panels is bring all the 20 amp circuits to one side of the panel then on the other side all the 15 amp circuits. Balance the double poles to each side like this

matrix733 11-28-2007 06:07 PM

Thanks again, it looks neater and definitely balanced. Stubbie, you have an archive of these pictures or what? You seem to dig out or create some really clear-cut pictures.

Stubbie 11-28-2007 06:22 PM

Yeah I like fooling with this stuff here is how it would look in a sub-panel situation......Panel installed by MDshunk


http://img.photobucket.com/albums/v3.../Tallpanel.jpg


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