Service Panel and the ground wire---Does this look correct?

MikeT · February 23, 2010, 11:04:30 PM

Below is a shot of my service panel. I think I am close to calling for an inspection but would like to make sure I am doing things correctly. My question concern the ground wire. My wire is actually six copper wires in a strand. I have it running up into the service panel from the lower left, and then it goes up the left side and connects around the screw on the top part of the right bus. Unlike all the other wires, this one didn't seem to have a slot to go into. So I looped it around the green screw and tightened it.

Does that seem right?

MountainDon · February 23, 2010, 11:44:21 PM

It should work, but something doesn't look quite right. I usually have to get out my electricians manual to be certain but here's from memory.

Different panel brands are set up differently on the inside. It's hard to tell from the photo but there should be a buss that all the individual circuit white (neutral) wires connect to. There should also be a buss that all the individual circuit bare ground wires connect to. There should be one interconnection, called a bond, between the white and the ground. That is achieved in different ways by different manufacturers. If it looks like that's what you have you'll find out for sure when the inspector has his look.

There should also be a connection from the ground buss to a ground rod, in the earth or metal water pipe, concrete rebar, whatever.

February 24, 2010, 12:02:30 AM

Thanks, Don. The panel is a Siemens 200 A. The ground wire goes from the buss bar down to two ground rods that are about ten feet apart.

ChuckinVa · February 24, 2010, 03:47:51 AM

Mike,
Does the Green Screw go all the way in to the load center box? If so, then that might be the bond from the neutral to the can. Is there a lug on the other neutral bar on the left like the one you have the neutral neutral conductor installed under on the right? If that is the case I think that is where your ground wire should go, or there is also a seperate ground bar available that screws into the load center box, where you see the extra holes pre drilled and tapped in the box. It has a large lug for the ground wire . As Mountain Don suggests the inspector will clarify it for you real quick but in our area that would mean a second inspection required after you corrected it and an additional charge.

EDIT picture link - MD

MikeT · February 24, 2010, 08:59:41 AM

Thanks Chuck. The green screw that the ground wire is currently looped to does NOT screw into the box as far as I can tell. It just screws a bit into the metal tab, then it hits plastic. On the left hand buss, there is also a place for the screw, but it is also a tab. On the other hand, there is a slot for a larger wire that is held in place by a nut that requires a hex head. In the picture, you can see the tab I am referring to on the left hand buss at the top. And immediately next to it is that slot that I suppose could be for the ground....the green screw is what is throwing me...

February 24, 2010, 10:37:44 AM

Thanks for the picture Chuck. Mike, if your box has a ground buss on the left edge, with a large lug, like the one in Chuck's picture, I believe the incoming ground should attach there.

The Square D panels I'm familiar with come with a long green screw in a plastic bag. It is to be screwed through one of the neutral buss bars to make the bond connection to the ground, via the metal of the case.

Have you a test meter? There should be an internal jumper/connection from the left neutral buss to the right neutral buss. I'd make sure on that. Then with the incoming ground wire connected to the ground buss check to see if there is connection from ground to neutral.

NEC states there must be one and only one bond or connection from neutral to ground someplace in the system. It is usually in the panel. Because sometimes there are reasons you do not want the panel ground and neutral to be bonded it is usual for that to be done with a removable screw. (If you had a sub panel next to the main panel, you would want the main to be bonded, but not the sub, for example.)

devildog · February 24, 2010, 10:43:53 AM

It may not be a problem where your at,but in florida we were required by our inspector to use solid ground.You cam make a quick call to your local inspector to see what he wants. If your cables come from the pole directly to your meter and then to your panel you can put ground and neutral wires together. But if your required to have a disconnect in between meter and panel they need to be seperated from what I remember,Like a mobile home.
Darrell

MountainDon · February 24, 2010, 01:28:40 PM

It just occurred to me that the green screw may be the bond between the ground and the neutral buss. When the screw is in place the bond is complete and when the screw is removed the bond is broken. Use of a test meter should be able to determine if that is true.

Just a guess, mind you.

rocking23nf · February 24, 2010, 01:51:48 PM

How is your ground wire grounded at the other end? is it attached to a cold water pipe or a copper rod in the ground?

February 24, 2010, 04:28:57 PM

My copper ground wire is attached to two ground rods, located about 10 feet apart and in good soil.

mt

ChuckinVa · February 24, 2010, 09:52:53 PM

MountainDon is correct. The green screw is the way you bond the neutral and ground together.If you were to unscrew the green ground screw then the two neutral bars would be seperated and you could use the left side for the grounds and the right for your neutrals.. Your Neutral would be isolated from the ground. In the picture I attempted to link to ( Thanks MD)There is a seperate ground bar. Depending on the number of circuits you are going to you might need to add one. Move all your grounds to the ground bar and keep your neutrals on the two neutral bars and you should be good to go. As Devildog indicated we use solid wire for grounding on residential services.one other thing I believe your romex needs to be stapled within 6" of the box. Normally you would cut a 2X piece of wood mount it in the wall cavity and then staple the wires to the 2X.
CHUCK

MikeT · February 24, 2010, 10:48:24 PM

Thanks Guys. I will head down there this weekend and examine the set up in more detail before I call for the inspection next week. I might take my picture over to one of the master electricians who are always working on a project at the college. I bought them a six pack a little over a year ago and they gave me lots of help, goodies and got me the service panel wholesale.

mt

MountainDon · February 24, 2010, 10:59:12 PM

I was looking over your picture and am not sure of something else. Where the Romex enters the bottom of the enclosure I can't tell if there are any cables clamps to secure the Romex and to keep the Romex away from the hole edges through the sheet metal.

And to tell you the truth I'm not clear on what is required. On the cabin everything going in and out of the panel enclosure was through conduit, so the situation was a little different. Here at home it's been so many years since I added circuits and wires I don't recall what I did and it's all hidden now behind sheetrock and the inner panel cover so I can't tell with just a glance.

These things.... (non-metallic cable clamp)

I did use these on the DC side where wires entered the charge controller enclosure.

MikeT · February 24, 2010, 11:03:45 PM

It is hard to tell, but if you look in the lower right corner, you can see two types of strain relief plugs. They are plastic but a few different styles. I have some like you showed, but I also tried other styles too. I followed the instruction on each type and put two wires through where it was permitted.

mt