Ground and Neutral Bar Connections Swapped in Panelboard

[philly]

I'm looking at a 120/208V panelbaord that is fed from secondary of small 30kVA transformer so is considered SDS but not service entrance.

In this panel the neutral bar appears to have the grounded conductor (neutral) from the transformer connected to it and the ground bar is connected to panel enclosure. There appears to be a cable connection bonding these (2) bars within the panel that would serve as the supply side bonding jumper (SSBJ).

It appears however that when the contractor installed all of the branch circuit neutrals and EGC's to circuits fed from the panel they flip-flopped the connections and connected all branch circuit neutrals to ground bar, and all branch circuit EGC's to neutral bar.

Are there any issues with having these branch circuit EGC's and neutrals swapped given the fact that there is a SSBJ in this panel? I know that without this bonding jumper this would not be allowed as it would not be permissible to have neutral current flowing through the ground and equipment enclosure.

 

[jaggedben]

What you're calling an SSBJ sounds like the system bonding jumper (SBJ). An SSBJ is something else.

First, it sounds like there is at least a code violation of not using the terminal bars in the panel as the instructions or labeling direct.

As far as whether it's unsafe... Probably under heavy load it's suspect. You say the SBJ 'appears to be a cable'. Is it field installed or factory? How big is it? My concern would be if it's not big enough to carry all the neutral current. The panel's intended neutral bar would be able to carry the full rating of the panel. The bonding jumper likely does not, whether factory or field installed.

 

[philly]

What you're calling an SSBJ sounds like the system bonding jumper (SBJ). An SSBJ is something else.

First, it sounds like there is at least a code violation of not using the terminal bars in the panel as the instructions or labeling direct.

As far as whether it's unsafe... Probably under heavy load it's suspect. You say the SBJ 'appears to be a cable'. Is it field installed or factory? How big is it? My concern would be if it's not big enough to carry all the neutral current. The panel's intended neutral bar would be able to carry the full rating of the panel. The bonding jumper likely does not, whether factory or field installed.

Yes my mistake I meant to reference SBJ not SSBJ.

Ok yes I see your point regarding the SBJ not being large enough to carry neutral current. This appears to be a field installed SBJ and from photos looks to be around #8 or #6 AWG. The neutral (grounded conductor) coming into the panel appears to be a #2AWG or maybe even a bit larger.

So if I'm understanding correctly typically the neutral bar is rated to carry full rating of panel (Lets say a 100A panel) and then obviously the neutral conductor cable to the panel is sized accordingly to carry full expected rating of unbalance (typically sized the same as ungrounded conductors).

With the SBJ being sized in accordance with 250.102 this may not be large enough to carry the full expected neutral current that was passing between ground bar and neutral bar? Could this bonding jumper simply be increased in size to match the neutral conductor size to the panel (although this still doesn't resolve code violation of using terminal bars in panel as instructed/labeled)

 

[jaggedben]

...

With the SBJ being sized in accordance with 250.102 this may not be large enough to carry the full expected neutral current that was passing between ground bar and neutral bar? Could this bonding jumper simply be increased in size to match the neutral conductor size to the panel (although this still doesn't resolve code violation of using terminal bars in panel as instructed/labeled)

Increasing the size would make it safer, but arguably not compliant.
I would just swap the wires to where they should be.

 

[Tulsa Electrician]

If your SBJ is at the panle. You need to make sure there is not one added in the SDS. An indicator would be if no GEC is in the panel. If the GEC is at the SDS. Then you will have a code issue.

Look for wire exiting the SDS not in conduit heading for an electrode. If you see one than the GEC most likely at the SDS. Then you have to choose what to fix.