Square D EZ Meter-Pak grounding

[19billdobaggy]

Hello all, first time post but I've been reading the forums for some time. I'm primarily a service electrician, but my company is beginning to dive in to new construction. Today I marked out the install of an 800 amp EZ meter-pak service on a 2 tenant building. Two 4" conduits are bringing parallel 500s into the bottom of the center section, which is simply lugs for the grounded and ungrounded conductors.

The left section plugs into the center section, you bolt the busses together, and 3 small bolts secure cabinet to cabinet. This left section has a 100 amp 3ph breaker and meter for the house panel, as well as a 200 amp 3ph breaker and meter for the retail space. There are 2 lugs for grounded conductors, and 2 lugs for grounding conductors. No bonding strap provided.

The right section plugs in and bolts up the same way. It has a 400 amp 3ph breaker and meter for the (maybe) breakfast restaurant. Knowing we would be running parallels, this section also has 2 lugs for grounded conductors, and 2 lugs for grounding conductors. Here a bonding strap was provided to connect the grounded conductor lugs to the can.

I'm going through the codebook and handbook trying to figure out what grounding/bonding requirements I will have here. The inspector was useless, he said for anything over 600 amps they just refer to the drawings. The only thing the drawings say regarding grounding is "grounding shall consist of copper conductors in conduit with bolted or brazed connection to each illustration below for the ground. Grounding and bonding shall comply with NEC articles 230 and 250. All metallic raceways shall be grounded." The "illustration below" shows concrete encased electrode, building steel, water service piping, ground rods, and ground ring, all connected to a #3 awg cu conductor. I can easily do ground rods, I can easily do concrete encased as the inner slab is not yet poured, and I can easily do structural steel. All of the water piping visible is plastic. The exterior is graded and landscaped so I don't see a ring being an option. I had in my head that you just had to utilize 2 of the acceptable grounding electrodes? I've done smaller services in the past with just structural steel and ground rods and never had an issue with any inspector. So that's one question...

Next, am I missing a bonding strap in the left section? The six small bolts that connect the 3 sections together can't be an acceptable connection... moving on...

This is definitely 1 service. Multiple meters. Because it is one service, all gec's would tie together as 1 grounding system, yes? One structural steel ground? One concrete encased electrode? One set of ground rods? All tied together at a common point? I'm stuck thinking that I'm missing a bonding strap in that left cabinet. I don't think I need to run 1 of everything for each side because it is one service, but I do need the left and right sections to be securely bonded to each other. If I add a strap in the left section, the grounding lugs would be bonded to the grounded conductor busbar, which runs through the middle section to the right section, where the bonding strap connects its grounding lugs to the grounded conductor busbar.

I know. It's a lot. I've always been more of a fixer than an installer, but I take pride in my work and I want to get this right and understand the how and why. I'm happy to provide more info and I will look up any applicable code articles. I've been cruising 250 this evening. Thanks in advance!

 

[electrofelon]

So can you clarify you have no single main breaker, just three meters, each serving it's own breaker, so three breakers/service disconnects?

 

[19billdobaggy]

That’s correct. Just lugs connected to busbars.

 

[electrofelon]

I've done those now and then, but I don't recall ever doing one without a MB. Actually I do have a 5 meter MLO one at a slow moving job that I'll be installing in the next month or two. Anyway, it's all service equipment so everything should be bonded directly or indirectly to the neutral. Yes it appears the left section is missing the bonding strap.

You need use whatever qualifying electrodes exist and connect them to the neutral bar. If none exist you will have to install one, usually two rods. I would install the GEC(s) to the center section. You may have to add lugs if they didn't provide spares for grounding connections.

 

[19billdobaggy]

Yes, unsure why there is no MCB. Around here, and I did ask the Duke engineer for this project, the power companies don’t want our grounding/bonding in their enclosure. The center section will have only the incoming 500s from the pole that they pull in and land. I’ll get the same result landing the grounds in either the left or right section though. Now I need to order that bonding strap ASAP... thanks for your input! The last multi meter assembly I did was residential and 10 years ago.

 

[electrofelon]

Yes, unsure why there is no MCB. Around here, and I did ask the Duke engineer for this project, the power companies don’t want our grounding/bonding in their enclosure. The center section will have only the incoming 500s from the pole that they pull in and land. I’ll get the same result landing the grounds in either the left or right section though. Now I need to order that bonding strap ASAP... thanks for your input! The last multi meter assembly I did was residential and 10 years ago.

Typically there will be no MCB if there are 6 or less meters. , 2-6 switch rule.

There argument doesn't really make any sense but whatever. For one thing if there was a MCB the GEC would HAVE TO land I'm that section. Without a MCB, the other sections are still "theirs" in terms of being locked and unmetered (except the customer access parts).

 

[19billdobaggy]

I looked at this again this morning and I’m even more uncomfortable with it. The one bonding strap provided goes in the center section. That means they’re relying on the 3 1/4-20 bolts that attach each outside section to the middle to provide an appropriate bond. I don’t see any factory holes in the left or right section near the neutral lugs to install a bonding strap or screw. It’s just very strange to me. I think I’ll call Square D and have them confirm that the 3 sections are bonded solely by the 1/4-20 bolts.

 

[19billdobaggy]

And even if I landed the gec’s in the center, the grounds to the individual panels would still land in the left and right sections, only bonded to the cans. Weird.

 

[kwired]

And even if I landed the gec’s in the center, the grounds to the individual panels would still land in the left and right sections, only bonded to the cans. Weird.

Those "grounds to individual panels" are not GEC they are EGC.

I haven't used one of these EZ meter centers in some time, but seem to recall you either install a main disconnect section or you can install a main lug section if you are taking advantage of six disconnect rule. You use the same sections for the outgoing feeders whether there is a main or just main lugs. I don't recall them having option to bond neutral in anything but incoming main section units.

EGC does depend on bolting the cabinets together, make sure you tighten them properly and use any washers they intended you to use for improving bonding as well. They were tested and listed for this.

 

[electrofelon]

Those "grounds to individual panels" are not GEC they are EGC.

I haven't used one of these EZ meter centers in some time, but seem to recall you either install a main disconnect section or you can install a main lug section if you are taking advantage of six disconnect rule. You use the same sections for the outgoing feeders whether there is a main or just main lugs. I don't recall them having option to bond neutral in anything but incoming main section units.

EGC does depend on bolting the cabinets together, make sure you tighten them properly and use any washers they intended you to use for improving bonding as well. They were tested and listed for this.

I guess the bolts holding section could be the bonding means. It would need to be "service bonding" per 250.92, IIRC the word "wrench tight" is in there. Hopefully they have star washers or serrated nuts to bite thru the paint. They have a foam gasket between the mating surfaces.

 

[kwired]

I guess the bolts holding section could be the bonding means. It would need to be "service bonding" per 250.92, IIRC the word "wrench tight" is in there. Hopefully they have star washers or serrated nuts to bite thru the paint. They have a foam gasket between the mating surfaces.

I think listing probably comes into play here. If your "main" compartment contains the service disconnect then obviously the accessory enclosure walls are in the EGC path.

These units are modular and none of them are designed to be used in a stand alone situation, they all must connect to at least a main lug or main switch/fuse or main breaker unit. That fact sort of treats the entire assembly as one listed unit, though there are options on that assembly.