Should the neutrals and grounds in my service panel be separated on the two different bars?

Question

I have a SquareD QO, 1 phase, 24 spaces, 34 circuits, 100A convertible main breaker, PoN, NEMA1, combo cover panel in my house as the main house panel. I had it installed by a licensed electrician over two years ago.

I had a friend tell me a horror story about his panel install so I took the panel cover off of mine just to inspect it. I saw there are 4 neutral bars on this panel, two bars high and two bars low. One of each on both sides. I noticed that he put all of the neutrals on the upper bars on both sides and the grounds on the lower bars on both sides.

Then I saw the grounding wire screwed in the lower bar on the ride side, the grounding wire goes outside to my grounding rod. It looks like he grounded it from the neutral bus that would go to a sub panel.

Should the neutrals and grounds be separated like that on the two different bars? And should there be a ground off the lower neutral bar to the grounding rod?

Part of me doesn’t think it’s correct, the reason why is this panel has 24 spaces, if the neutrals are on the two top bars and grounds on the lower two bars there isn’t enough room for 24 breakers?

Would I have to double up some of the neutrals and grounds or should there be one neutral and one ground together in one slot? I have read that you can put one neutral and one ground together only if it’s in the main panel.

Answer 1

The MAIN PANEL contains the first disconnect past the meter. The ground rod line must connect here (to the ground bar if they are separated). Also, here is the location of the neutral-ground equipotential bond tying neutrals and grounds together.

The panel you linked has four little NEUTRAL bars up high near the top of the panel. Your ACTUAL panel has three little NEUTRAl bars up high near the top of the panel. Note that all these are insulated from the panel chassis, that's what makes them neutral bars and not ground bars. So clearly your panel is NOT the one you linked. I suspect it is a 24/24 (i.e. allows zero tandem breakers).

If you had bars down low near the bottom of the panel, those would be optional, added GROUND bars. They would not be insulated from the chassis. Separating neutrals and grounds is a) mandatory in a subpanel. b) optional, but elegant and well-done in a main panel.

In a MAIN panel, grounds are allowed as guests on the neutral bar. Cheap builders rely on that a lot.

This panel can be configured either as a main panel or a subpanel.

I noticed that he put all of the neutrals on the upper bars on both sides and the grounds on the lower bars on both sides. Should the neutrals and grounds be separated like that on the two different bars?

On your panel, the "bars near the top of the panel" are staircased a little bit for easy wire entry. You seem to be calling that "upper" and "lower". That is wasted, they are all neutral bars. They are all insulated from the panel. Your panel according to your photo has no accessory ground bars. Feel free to add some. The panel labeling lists specific model numbers of ground bar designed to fit pre-drilled, pre-tapped sites all over the panel.

If this is a main panel, it doesn't matter. Separation is mandatory on a subpanel.

Note that in a main panel, you still have that neutral-ground equipotential bond.

And should there be a ground off the lower neutral bar to the grounding rod?

YES. The Grounding Electrode System (ground rod and connecting wires) connects to the GROUND bar if we're in a place where that matters.

Part of me doesn’t think it’s correct, the reason why is this panel has 24 spaces, if the neutrals are on the two top bars and grounds on the lower two bars there isn’t enough room for 24 breakers?

Well, given that you linked the wrong panel, I suspect your panel isn't actually a 24/34, it's a 24/24. There have to be enough neutral positions, or UL won't give the panel a UL Listing.

However, this is also a Plug-On Neutral (PON) panel designed to allow AFCI and GFCI breakers to pick up neutral by the vertical rails instead of taking a space on the neutral bar. Food for thought.

UL requires each neutral must be alone in its slot.

Would I have to double up some of the neutrals and grounds or should there be one neutral and one ground together in one slot?

NEC 408.21 [Neutral] Terminations. Each [neutral] shell terminate within the panelboard in an individual terminal that is not also used for another conductor.

However this has been a UL requirement for >50 years, just people weren't reading the instructions, so they had to put it into NEC.

Especially do not put the circuit's ground next to the neutral. If that had a connection problem, it could electrify all the grounds on the circuit!

However, GROUNDS are a different deal. Read the panel labeling, it often allows multiple grounds per slot.

I have read that you can put one neutral and one ground together only if it’s in the main panel.

Throw that book in the trash. It's horsepuckey. As you plainly see, neutrals must be alone.

Now it is true that grounds are allowed as guests on the neutral bar, but they share a spot, they can only share with other grounds, and to the limits specified in the panel labeling.

Answer 2

Without a picture hard to tell for sure, but basically:

A typical panel will have separate ground and neutral bars. If it is the main panel then:

• The neutral bars are grounded to the cabinet, usually with a clearly marked screw.
• Grounds (whether branch circuits of the grounding rod wire) can be placed on the neutral bars but neutrals can't be placed on the ground bars.

While it depends on the specific panel, in general it is one wire per screw on the neutral bars but 2 or possibly even 3 (depending on the panel, depending on wire size) ground wires per screw on the ground bars.

In theory there should always be enough neutral and ground screws for every breaker (counting the 2 or 3 wires permitted per ground screw). However, there may be some panels with not-quite-enough screws, particularly if 1/2 size breakers are used (34 vs. 24). However, there are also usually some 240V breakers (e.g., water heater, HVAC, cooktop) that don't use a neutral at all or at least cut the number of neutrals needed down because they use one neutral for a double-breaker instead of two neutrals for two single breakers.

So it is quite possible that your panel may look a little strange but be 100% perfectly acceptable and code-compliant. But can't tell for sure without a picture.

Answer 3

OK here: While I agree with most of Manassehk said, I have to add that it's a good practice to put all the neutrals on their own bus bars, directly connected to the mains neutral, virtually eliminating the possibility of unbalanced neutral current flowing via the ground bars, even though they are electrically connected in a main panel. The other advantage is if the OP ever wants to install a whole house generator with a 200 amp transfer switch between the meter and the main panel, the main panel needs to get treated as a sub-panel, meaning the grounds and neutrals must be isolated (floating), having all the neutrals and grounds on separate bus bars would make that install a lot easier.