Bonded Neutrals???

[Jeff Gainey]

I need another opinion please. This subpanel in a condo has the 4 wire service but the way I read it the neutrals are bonded while the grounds are not bonded. While I see the bonding screw on the neutrals I do not find any bonding screw on the ground side. Thanks in advance. As always I appreciate the feedback.

[Gunnar Alquist]

Jeff,

The grounding conductors should be bonded to the panel box.

Neutrals (grounded conductors) should be isolated from both the panel box and the grounding conductors.

[John Kogel]

Apprentice gets a slap to the head, he got them reversed.

PS, most apprentices know their stuff, fresh out of schooling. So then it was the old guy who left his peepers in the truck? ;)

[Jim Port]

The bond screw on the upper left needs to be removed. The grounding conductors need to be moved to an auxillary ground bus.

The panel as shown is wired as a service panel except for the 4 wire feed.

[Jerry Peck]

The bond screw on the upper left needs to be removed. The grounding conductors need to be moved to an auxillary ground bus.

Agreed. I looks like they removed a connector plate which ties the terminal bar to the bus and figure that would work - except they got the two backward by bonding the neutral and isolating the ground - if they had installed a bonding jumper from the grounding terminal bar is might have worked out ... not been correctly done, but at least have accomplished the same thing.

As Jim said, modifying the panel removing that connector plate is not the proper way - move the grounding conductors to an auxiliary ground bar (and either remove that terminal bar or find a replacement connector and install it where it should be - removing that terminal bar just adds to what is done wrong, replacing that connector puts it back like it was made and removes the potential for using an isolated bar for a future neutral which then goes nowhere and the circuit doesn't work).

[Jim Port]

Square D does not use a connector bar. Both bus are factory neutrals and are bridged under the backer plate.

Grounding bars mount on raised bumps and screw into the back of the panel, typically in 3 locations.

[Jerry Peck]

Square D does not use a connector bar. Both bus are factory neutrals and are bridged under the backer plate.

Grounding bars mount on raised bumps and screw into the back of the panel, typically in 3 locations.

That looks like the right terminal bar has been 'disconnected' from the neutral bar in back - but that is not the way they are put together? That means the right terminal bar is and always will be a neutral terminal bar and cannot be isolated/insulated/removed from the neutral?

[Jim Port]

Correct , both are neutral bars by design.

[Jerry Peck]

Correct , both are neutral bars by design.

Which means that when used as 'other than service equipment', a separate grounding terminal bar is required to be installed - does one come with it?

[Jim Port]

An auxiliary ground bar is a separate purchase.

[John Kogel]

An auxiliary ground bar is a separate purchase.Thanks, Jim. That explains a lot right there.

[Jerry Peck]

An auxiliary ground bar is a separate purchase.


Thanks, Jim. That explains a lot right there.

I can see the installer now ... Dang! They forgot to include that auxiliary grounding terminal bar AGAIN! Seems like they forget to include that thing every time.

Well ... seems to be a reason it is not included ... :D ... it probably costs an extra half-buck to make and include, and they can get 2 and a half bucks for it by selling it separately ... that's another 3 bucks per panel they make ... at the expense of having it installed correctly. :(

[Gunnar Alquist]

Square D does not use a connector bar. Both bus are factory neutrals and are bridged under the backer plate. Grounding bars mount on raised bumps and screw into the back of the panel, typically in 3 locations.

Is this true for most/all panels? I occasionally see panels (Cutler-Hammer, I believe) that have had a connector bar removed between the two grounded terminal blocks to separate the grounded from the grounding conductors. But, there has been a way to bond the grounded terminal block to the panelbox.

The problem that I see here is that this kind of detail is beyond most of us home inspectors. Knowing the specifics of installation instructions of all panel manufacturers (or furnaces, or whatever) is very specific. I think that what Jeff found is perfect, but knowing which panel can have the connector bar removed and which cannot is outside of the definition of a home inspection.

2 cents.

[Jim Port]

GE or Westinghouse is the only one I have seen with a tie bar. I mainly use cutler-Hammer or Square D. Can't speak for the others.

- - - Updated - - -

The bars are not always needed so it is unnecessary to include them in every panel..they are more like 7-10$, so you are talking about a fair amount times the number of panels produced.

I agree Gunnar , but many of these issues can be resolved by looking at the panel wiring diagram.

[Jerry Peck]

but knowing which panel can have the connector bar removed and which cannot is outside of the definition of a home inspection.


I agree Gunnar , but many of these issues can be resolved by looking at the panel wiring diagram.

Jim is correct, if something is removable, it will be shown on the label or wiring schematic.

Likewise, if something is permitted to be added (such as that auxiliary grounding terminal bar), it will be shown on the label or wiring schematic.

Some panels have metal cross bars which secure the neutral terminal bar on one side to the neutral terminal bar on the other side, when removable, the label or schematic will show it, and some will show the metal bar being replaced with a plastic bar - if the metal bar is removed (to isolate one side terminal bar from ground) then the plastic bar is required to be installed in its place - not left with the metal bar removed and nothing installed ... again, that will be shown on the label or the schematic.

Home inspectors need to get used to looking at the labels and schematics as reading those will answer almost all questions regarding the installation of that panelboard. Yes, sometimes it is a chore to take the time to read the labels and schematic, but you may make an incorrect comment by not reading them (you may leave something off which you should have written up, or write something up which you should have left off).

We are currently going through some revisions to UL 67.