Square D Q0 200A Panel - how to convert to sub panel (separate neutral / ground bars)

pclausen · Aug 31, 2015

So I got this 1980's Square D panel (there are 2 actually, but I'm putting this one behind a transfer switch).

Here's the label:

And here's another part of the label, showing the bonding screen between the neutral bar and box. I know I need to remove this.

View of the entire panel. Note that I have already removed the original feeder wires, which entered in the top left corner. I have installed a 2" metal plug there. I have also marked the 4GA ground wire with a green arrow that goes to the ground rod. This will be pulled and connected to the Asco transfer switch instead.

Closeup of the neutral bars. Note how the original installer randomly used both the inner and outer bars for neutral and ground connections. The green arrows are the bars I intend to dedicate to ground. The yellow arrow points to the screw that is bonding the neutral bar to the box. As stated above, I'll be removing it.

Another angle of the neutral/ground bars. I don't see a way to isolate the inner bars from the main neutral bar.

So my plan is to move all neutral connections to the outer bars, unscrew the 2 inner "ground" bars, and drill holes and bolt then directly to the box as seen in the very crude illustration below:

Unless I'm missing something, it would seem that unlike Cutler Hammer, these Square D Q0 panels, do not offer an easy way to separate ground from neutral, thereby not making them an ideal choice for a sub panel in the first place?

Can you suggest an easier method to turn this panel into a sub panel?

PS In case you're wondering what that thick neutral wire still in the panel is, that feeds a 100A subpanel where my 3 outdoor units reside.

Thanks

check · Aug 31, 2015

What the heck? I have several Square D panels, and I have never seen the neutral and ground connected to each other.

GLyford · Aug 31, 2015

Would it be easier to leave all the neutrals on those 4 bars, and just buy 2 new bars to mount as you want? You'd have half as many wires to move, unless they put a bunch of grounds and neutrals in the same connection. Last time I checked (it's been a while) ground bars were cheap.

Ed L · Aug 31, 2015

GLyford said:
Would it be easier to leave all the neutrals on those 4 bars, and just buy 2 new bars to mount as you want? You'd have half as many wires to move, unless they put a bunch of grounds and neutrals in the same connection. Last time I checked (it's been a while) ground bars were cheap.

This.

One has to buy the ground bars separate.

Ed

pclausen · Aug 31, 2015

Appreciate the feedback. I ended up removing the 2 inner bars and installing a new ground bar. It was less than $5 so no big deal.

Here's the final result:

Since most of the circuits in this panel are 240V, most of the "ground wires" were actually neutral wires. So I only wired the 120V circuits to the ground bar, using wire nuts and #12 green wire (had a 500' spool laying around). I did double up some of the #14 grounds into a single #12 green wire. I think that's ok? There were no 4 wire 240V circuits in the panel.

A view of both panels. Getting that copper 3/0 wire through that 2" conduit was a total pain.

And a view of the Asco 200A transfer switch once I got power back on.

I'll be installing a 36KW diesel generator. Even at that size, it would not have been able to pull both panels, so I decided to have it just power the panel with all the HVAC units and well pump, and a few other amenities. I might install a 1.5" conduit between the panels, and extend some other essential circuits, like the kitchen, fridge, and TV and office circuits over into panel 2.

Here's a diagram of the circuits in each panel. There are some heavy hitters in panel 2 (which is on the transfer switch).

quicksandfarmer · Aug 31, 2015

pclausen said:
Since most of the circuits in this panel are 240V, most of the "ground wires" were actually neutral wires. So I only wired the 120V circuits to the ground bar, using wire nuts and #12 green wire (had a 500' spool laying around). I did double up some of the #14 grounds into a single #12 green wire. I think that's ok? There were no 4 wire 240V circuits in the panel.

Not an electrician, but I don't think that's right. Every circuit has to have a ground, neutral is optional. Decades ago it used to be OK to use ground as neutral in a 220v circuit, but nowadays if you want neutral you have to run a wire for it. So every circuit should have a wire going to the ground bus, only circuits with a neutral wire should have a wire going to the neutral bus.

schmism · Aug 31, 2015

check said:
What the heck? I have several Square D panels, and I have never seen the neutral and ground connected to each other.

check again.

per code, the main box has to have the grounds tied to the neutrals. in subpanels they want them separate with a ground rod at each sup panel.

pclausen · Aug 31, 2015

quicksandfarmer said:
Not an electrician, but I don't think that's right. Every circuit has to have a ground, neutral is optional. Decades ago it used to be OK to use ground as neutral in a 220v circuit, but nowadays if you want neutral you have to run a wire for it. So every circuit should have a wire going to the ground bus, only circuits with a neutral wire should have a wire going to the neutral bus.

I was wondering about that. The fact that the original wiring was all randomly wired between the neutral and ground bars threw me off on the 220v circuits.

Easy enough to change. I'll do that tomorrow (house in unoccupied at the moment).

Thanks!

quicksandfarmer · Aug 31, 2015

I'm also trying to figure out the thick aluminum ground conductor. It looks like it's going to neutral on both panels. Are either of the two panels we see the main service entrance, or are they subpanels? Ground and neutral have to be bonded at the main entrance and then separate everywhere else in the system. If these are subpanels that thick ground conductor has to go to ground, not neutral.

Again, not an electrician, although I did study electrical engineering in school.