Does it make a difference if Neutral and Ground Busbars are shared on 120/240 VAC Panel when I ad a Subpanel?

[jim dungar]

May or may not have been when installed

Two neutrals under one screw has always been a violation, under 110.3 and UL Listing procedures.
Because so many installers were ignoring manufacturers instruction, an explicit prohibition was added to the NEC.

 

[Little Bill]

The panel pictured does have all the bus es connected together so it is correct. This panel is likely to be a "Service Only" panel with the Neutral permanently bonded without a removable bond.

Curious, where do you see the neutral permanently bonded in the picture?

 

[wwhitney]

This panel is likely to be a "Service Only" panel with the Neutral permanently bonded without a removable bond.

It is not, the green screw just above the main circuit breaker is the removable MBJ.

Cheers, Wayne

 

[Rick 0920]

I'm wondering if there is at least 6" of conductor emerging from the raceway on the feeder and why they used expensive
Myers Hubs on an indoor application?

 

[Rick 0920]

1. Main Panel vs. Subpanel Bonding Rules​

• In the main panel, the neutral (N) and ground (G) are bonded together. This is why you see neutral and ground wires on both bars in your main panel. The bonding ensures that any fault current has a direct path back to the source.
• In a subpanel, neutral and ground must remain separate. This prevents unwanted ground currents (which can cause safety hazards and improper operation of circuit breakers).

2. Why Run Separate Neutral and Ground to the Subpanel?​

• The neutral wire carries current under normal operation, while the ground wire is only for faults.
• If you bond neutral and ground in the subpanel, return current could travel on both, turning ground wires into active conductors—which is unsafe.
• Keeping them separate in a subpanel ensures that only the main panel handles the neutral-to-ground connection.

3. How to Wire the Subpanel Correctly​

• Run 4 conductorsfrom the main panel to the subpanel:
  • Hot 1 (H1)
  • Hot 2 (H2)
  • Neutral (N)
  • Ground (G)
• In the subpanel:
  • Keep neutral isolated (do not bond it to ground).
  • Connect the ground to a separate grounding bar, which is connected to the panel enclosure.
  • If the subpanel is in a detached structure, it may also require a grounding electrode (ground rod).

If you think I am right, Click a like and encourage me to contribute more for the community.

I feel that you are very accurate here Billy. I look forward to seeing more contributions from you.

 

[Installer]

Thanks every one. I think the wise thing to do is to decline to help.
Washington state lets a non electrician do work but it must pass inspection.
I'm not taking chances, because my buddy might opt out of the inspection.

Thanks again.

 

[Installer]

I'm wondering if there is at least 6" of conductor emerging from the raceway on the feeder and why they used expensive
Myers Hubs on an indoor application?

not necessary but thats all I could find at Home Depot

 

[Fred B]

It is not, the green screw just above the main circuit breaker is the removable MBJ.

Cheers, Wayne

must be the color saturation on my devise is off b'cuz I didn't see a green screw.

 

[LarryFine]

must be the color saturation on my devise is off b'cuz I didn't see a green screw.

Not real green, but the large Philips-head screw in the silver bar between the white circles:

 

[Little Bill]

Thanks every one. I think the wise thing to do is to decline to help.
Washington state lets a non electrician do work but it must pass inspection.
I'm not taking chances, because my buddy might opt out of the inspection.

Thanks again.

You might want to look at your drawing of the purposed installation. You are showing the line 2 (hot) going to the neutral bar and the neutral going to the line 2 lug.

Also, @Installer would you please update your profile to include your occupation?

 

[Rick 0920]

not necessary but thats all I could find at Home Depot

In the future, you can just use the RGC nipple with 2 locknuts (inside and outside) and a plastic bushing and save some $$$$.

 

[readydave8]

Two neutrals under one screw has always been a violation, under 110.3 and UL Listing procedures.
Because so many installers were ignoring manufacturers instruction, an explicit prohibition was added to the NEC.

Yes I've heard that before

I don't think any labels on panel nor installation instructions mentioned that. Where would I have found prohibition on 2 neutrals in same lug back in the day? UL listing?

Of course even today we use panels that come with ground bars that are OK to put more than 1 wire under a screw, explicitly not allowed for neutrals though

 

[jim dungar]

I don't think any labels on panel nor installation instructions mentioned that. Where would I have found prohibition on 2 neutrals in same lug back in the day? UL listing?

Most likely it was part of the neutral bar size capacity and torque values. Who has a 'new in the box' loadcenter from the 80s?
If the warning was blatant, ground and neutrals in the same hole probably wouldn't have been so common.

 

[readydave8]

Most likely it was part of the neutral bar size capacity and torque values. Who has a 'new in the box' loadcenter from the 80s?
If the warning was blatant, ground and neutrals in the same hole probably wouldn't have been so common.

Yes I think it was a secret code that no one was supposed to know

 

[ggunn]

1. Main Panel vs. Subpanel Bonding Rules​

• In the main panel, the neutral (N) and ground (G) are bonded together.

True except when there is a device like a main service disconnect or ATS ahead of the main panel where N and G are bonded.