Square D QO panel lack of neutral bar positions

[hbiss]

I talked about this several months ago when I first saw this installation. This panel is a 30 space/40 circuit 200A MB panel. The neutral bar was double and tripled and quadrupled up with neutrals and EGCs in the same holes. This is a full 30 space panel with only 31 neutral positions. There were no ground bars installed. You can add 10 tandem breakers and I have no idea where the 10 neutrals would go.

Although this panel is maybe 20 years old, new Square D QO panels like this are exactly the same with limited neutral bar positions. They do offer PON breakers which are more expensive.

So, in looking I see that the 40 space/40 circuit 200A MB version has an additional 10 position neutral bar. That position is there in the 30 space/40 circuit but there is no neutral bar in it. It would be a simple matter to take a Square D ground bar and mount it in that position with only one screw. That would give 10 additional neutral/EGC positions.

It probably would violate the listing but who would know or care? This is the panel in question. Look what I had to do with the EGCs with those blue/gray wire nuts! There are still 4 spare breaker slots left to be used. It needs 40 neutral positions, there are only 31. Not to mention ground buses.

Note the vacant neutral bar position on the left.


This is a QO 40 position, 40 circuit. Same thing as above but with the extra neutral bar on the left making 40 neutral bar positions.


What do you think about doing something that they should have done to begin with?

-Hal

 

[Genepires]

I am not a resi guy so please forgive my ignorance. this is not a sub panel right? (I think I see a EGC)

If not a sub panel, is it a code violation to simply remove section of pain and drill tap holes to mount another neutral on the panel? I guess one could probably get a neutral bar that is insulated from panel too if subpanel. so the question is can we add additional neutral or ground bars to listed equipment?

 

[Master Nater]

I am not a resi guy so please forgive my ignorance. this is not a sub panel right? (I think I see a EGC)

If not a sub panel, is it a code violation to simply remove section of pain and drill tap holes to mount another neutral on the panel? I guess one could probably get a neutral bar that is insulated from panel too if subpanel. so the question is can we add additional neutral or ground bars to listed equipment?

this is a good point. with the requirement of residential services to have an exterior service disconnect (or emergency disconnect) nearly all residential panels are now considered sub-panels and need to have separate neutral/EGC bars. this separate bar situation is overlooking the 80 spaces required (60 if you double up your EGC conductors) required for a 40space loadcenters that they advertize and are somehow listed for. this is disappointing from many angles. disappointing that UL has not required more considering the 40space listing. and disappointing that square d has not gotten with the updates on residential requirements.

i do not believe eaton is doing much better in this area, as i believe they do not come standard with ground bars, and must be bought separate, just like their covers. but i could be wrong. it's been a while since i've installed their stuff.

 

[electrofelon]

I pretty much always install ground bars in custom positions (i like them horizontally on the top and the bottom, not the sides).

And remember guys there's no such thing as "violating a listing". You do have to follow the instructions, but the instructions do not have to give you permission to do things, they can only tell you what you cannot do. An AHJ has incredibly broad power to find an installation unacceptable per 110.2.

 

[tthh]

The panels should have enough neutral and ground positions for full capacity.

 

[jim dungar]

The panels should have enough neutral and ground positions for full capacity.

They never have had to. There has always been the assumption some of the circuits will be multiwire, like a stove, and others will be two pole only, like a water heater.

 

[kwired]

Look what I had to do with the EGCs with those blue/gray wire nuts!

you can add EGC bars pretty easily for the grounding conductors and are allowed two conductors per hole for 14 or 12 AWG conductors.

 

[kwired]

I talked about this several months ago when I first saw this installation. This panel is a 30 space/40 circuit 200A MB panel. The neutral bar was double and tripled and quadrupled up with neutrals and EGCs in the same holes. This is a full 30 space panel with only 31 neutral positions. There were no ground bars installed. You can add 10 tandem breakers and I have no idea where the 10 neutrals would go.

Although this panel is maybe 20 years old, new Square D QO panels like this are exactly the same with limited neutral bar positions. They do offer PON breakers which are more expensive.

So, in looking I see that the 40 space/40 circuit 200A MB version has an additional 10 position neutral bar. That position is there in the 30 space/40 circuit but there is no neutral bar in it. It would be a simple matter to take a Square D ground bar and mount it in that position with only one screw. That would give 10 additional neutral/EGC positions.

It probably would violate the listing but who would know or care? This is the panel in question. Look what I had to do with the EGCs with those blue/gray wire nuts! There are still 4 spare breaker slots left to be used. It needs 40 neutral positions, there are only 31. Not to mention ground buses.

Note the vacant neutral bar position on the left.

View attachment 2582557
This is a QO 40 position, 40 circuit. Same thing as above but with the extra neutral bar on the left making 40 neutral bar positions.
View attachment 2582558

What do you think about doing something that they should have done to begin with?

-Hal

Is the same components, they just have different formula of what goes into that catalog number. I myself would add a piece of EGC bar in your situation. It is the same design as what they put there as well, just different lengths for different applications everything else is the same.
Note that only the top hole with the mounting screw in it is what provides continuity to the main neural bus whether factory assembled or you field modify it. I have encountered that connection fail a time or two, kind of surprising it holds up as well as it does with only a single 8-32 screw for the main connection into a tin plated copper bus where you have to be careful to not overtighten or it will strip threads.

 

[kwired]

I am not a resi guy so please forgive my ignorance. this is not a sub panel right? (I think I see a EGC)

If not a sub panel, is it a code violation to simply remove section of pain and drill tap holes to mount another neutral on the panel? I guess one could probably get a neutral bar that is insulated from panel too if subpanel. so the question is can we add additional neutral or ground bars to listed equipment?

Those panels have pre made mounting holes for EGC bars in at least three places. Generally one on each side and opposite end of the main lugs/breaker. All you need to do is purchase the right series grounding bars and they come with thread forming screws and have holes that line up with the holes in the enclosure. Off top of my head they make 9, 12, 15, 18, 23 space grounding bars that will all fit there.

 

[hbiss]

There has always been the assumption some of the circuits will be multiwire, like a stove, and others will be two pole only, like a water heater.

In the "old" days if I installed it, I would have had it full of MWBCs run with AC. No EGCs to speak of. Then along came NM and after that the proliferation of GFCI and AFCI breakers which made every circuit 2-wire Romex. Every circuit needs a neutral and at least one ground bar hole to share with another.

In this panel there is a 2-pole 20A, and two MWBCs that I added in EMT running around the basement for receptacles. So, we eliminated three neutrals on the neutral bar and one EGC and it's still overflowing.

I guess their solution is the PON. But you need a recent panel and the special breakers which I have never seen in use

I am not a resi guy so please forgive my ignorance. this is not a sub panel right? (I think I see a EGC)

If not a sub panel, is it a code violation to simply remove section of pain and drill tap holes to mount another neutral on the panel? I guess one could probably get a neutral bar that is insulated from panel too if subpanel. so the question is can we add additional neutral or ground bars to listed equipment?

No, it's not a sub panel and the insulated position for another neutral bar is already there. All I have to do is use a piece of ground bar, possibly shorten it, and screw it in place with one screw.

you can add EGC bars pretty easily for the grounding conductors and are allowed two conductors per hole for 14 or 12 AWG conductors... Those panels have pre made mounting holes for EGC bars in at least three places. Generally one on each side and opposite end of the main lugs/breaker. All you need to do is purchase the right series grounding bars and they come with thread forming screws and have holes that line up with the holes in the enclosure.

Yes, I know. But those EGCs were existing and connected to the neutral bars. (Actually, some weren't even connected, just hanging out in the mess!) I would have had to pigtail every one to ground bars that I would have installed at the bottom. This was just a neater solution.

Interesting about the ground bar mounting. If you look closely at this panel, there are no locations provided for ground bars. The new 40/40 PON panel seems to have plenty. When I read the installation instructions for ground bar mounting, they say to drill the pan with a certain size drill bit and use the included thread cutting screws if there are no pre-determined locations. How come the NEC makes a big deal about three threads engaging the sheet metal pan thickness (meaning we can't drill & tap for an 8/32) and people recommend taking a grinder and removing the paint?


-Hal

 

[jim dungar]

How come the NEC makes a big deal about three threads engaging the sheet metal pan thickness and people recommend taking a grinder and removing the paint?

The NEC requires a certain number of threads for untested installs. The manufacturer might supply a thick enough enclosure with specific threads that meets the NEC or, more probably passes the UL test.

Removing the paint is not required if you are counting on the screw threads making the metal to metal connection.

 

[hbiss]

No, I see what you are saying. I have mixed feelings about how to install ground bars to a pan if there are no provisions for them, especially when a manufacturer tells you to do it in a way that goes against what we have been told.

-Hal

 

[jim dungar]

especially when a manufacturer tells you to do it in a way that goes against what we have been told.

When I built UL508A control panels we never removed the paint. We simply used manufacturer supplied screws into a sufficiently thick back panel.

If you remove a factory installed and bar, I think you will find painted steel.

 

[Little Bill]

How come the NEC makes a big deal about three threads engaging the sheet metal pan thickness (meaning we can't drill & tap for an 8/32)

It's two threads, so you can drill and tap for a 10-32 screw.

 

[garbo]

It's two threads, so you can drill and tap for a 10-32 screw.

In my 42 circuit service panel I mounted ground bars on both sides & bottom of panel that had 16 or 18 openings drilled & tapped two 10/32 holes and ran a #6 copper wire daisy chained from each one to the neutral bar. Keep inside of panel neater.

 

[going_commando]

A separate ground bar has always been a good idea. I've been installing them for years and years. I'm a fan of QO, and this always freed up space on the neutral bars, and also future proofed the panel for a transfer switch installation since you could just toss out the green screw and bonding jumper to the ground bar. With new residential it's a non-issue because of AFCI requirements and plug on neutral breakers. For commercial, zero 2-pole loads is weird, and multi-wire branch circuits are common.

 

[busman]

It's two threads, so you can drill and tap for a 10-32 screw.

I think QO ground bars are 8-32 screws.

Mark

 

[jim dungar]

I think QO ground bars are 8-32 screws.

Mark

It is the number 32 that is important for most electrical enclosures.

 

[electrofelon]

I think most (all?) loadcenters are constructed with less than 16GA steel so technically a 32 tpi screw is not acceptable. That said i do it all the time and use 2 screws.

 

[jim dungar]

I think most (all?) loadcenters are constructed with less than 16GA steel so technically a 32 tpi screw is not acceptable. That said i do it all the time and use 2 screws.

The ground bar mounting hole locations are formed using a method that produces more metal for the threads. Think of a punch that forms a tube with a hole at the bottom of it. The walls of the tube provide the thickness for the screw threads.