Proper bonding at the main panel

I am a new inspector. I conducted a mockup inspection of one of the neighbor house that was built in 1991. It was hard for me to determine whether the grounding conductor was bonded with the grounded conductor. Can anyone see if it is or not? Your help is much appreciated. Thank you.

Sang, looking at the red box you’ll see the grounding electrode conductor attached to the bus bar that contains both neutrals and grounds. The green arrow points to what I think is a bonding screw connecting the metal cabinet to the bus bar on the right which is connected to the bus bar on the left by the tie bar near the top of the panel.

It appears that there are also multiple neutrals under a single screw, which is a deficiency because it complicates isolating circuits.

“Bonding jumper” refers to a strap, tie bar or other device that connects the neutral (grounded) conductors with the ground (grounding) conductors. In this case they’re both installed on the same bus bar and the grounding screw (if that’s what it is) bonds the metal cabinet to the other metallic parts of the system that could become energized. So although there isn’t a single bonding jumper as there would be if grounds and neutrals were each on their own separate bus bar, the condition is acceptable because the relevant components are electrically connected at the service panel.


A little hard to tell definitively from the pics but i would say it is likely. The screw on the top left, just above the terminal bus looks to be the bond to the enclosure and on the right side it looks like you could possibly isolate the left terminal bus if it was used as a sub. did you take a picture of the cover? there should be some more info on there to help you.

I zoomed in to the area that green arrow points and found out there was no screw installed in that spot. Yes on the double tapped neutrals. I called it out on my report. Where else should I look to verify the proper bonding?

is this the pic that you are referring to?

Yes sometimes the labels will give you information on the bussing or grounding. In this case not so much.

Kinda hard to tell from the photo, but you should see a bonding device connecting the metal cabinet to the bus bar with the grounds and neutrals somewhere. And… what Ryan said.

The panel bonding screw appears to be absent.

Sang, This is a scary picture. Be very careful where you put your hands around panels. Most of the shiny things, including the bus, can and will electrocute you if you give them the chance. You had to be really close to some energized components when you took this photo. Be careful.


The bond screw is absent. It goes where the green arrow points. The label inside the panel will show the location.

Square D does not split left and right into separate bus bars. They are both neutral bars.
A ground bar would need to be added if this was not a service.

The multiple cables in the large sleeve or connector is also wrong.

I agree the main bonding jumper (MBJ) is missing. Fortunately the service raceway is metallic so the system has been able to operate safely for almost 30 years because the metallic raceway is bonding the enclosure along with the solid bare copper bonding jumper.

Yes, but it still needs a bonding screw at the bus bar(s), no?

In my experience with Square-D panels the bonding screw would have a green head and be in one of these two positions. Enlarge the photo to see the circled areas over the main disconnect

Could you tell me where in the picture? I am confused on large sleeve or connector.

I am ignorant on this “service raceway” terminology. Could you educate me where this is on the picture?

Yes a main bonding jumper (can be a green screw) is still required.

Sure, the raceway containing the service entrance conductors (the conductors coming from the meter) is often called the service raceway.

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So how it could it still be “safe”, as you put it, if the bus bars weren’t “jumped”/bonded to the panel or why is it even need then?

Safely is a relative term if the service raceway were PVC or SE cable it would have been very unsafe. The original installation without the MBJ is incorrect however the neutral and the enclosure are still connected via the metallic service raceway which is connected to the meter enclosure where the neutral is bonded to the enclosure. So the enclosure is bonded to the neutral just not in the panel as required.

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Anything other than a case of energized conductor coming in contact with the metal cabinet?