Bond the 320 amp meter can to the service neutral and leave that bond there for the life of the service. Land the grounding electrode conductor wherever your utility allows: in the can, or at the panels through taps. For two sets of 2/0 copper service conductors that is one conductor run feeding one tap size into each panel, both sized in the steps below. Run no equipment grounding conductor between the meter and the first disconnect; on the supply side of the main breakers, the bonded neutral carries fault current. Which inspector story is right comes down to one thing: whether the breakers live in the panels or inside the meter main.
The three bonds that stay put
Three facts hold on every service, whichever way the inspector leans that month.
- The neutral bonds to every metal enclosure it passes through ahead of the main breakers. Meter can, gutter, raceway fittings: each one bonds to the grounded conductor. Most 320 amp meter mains arrive with that bond made at the factory.
- At each service disconnect, neutral and grounds share one bus. With main breakers in the panels, both panels bond neutral to case and land grounds on the same bar.
- No equipment grounding conductor exists between the meter and the first disconnect. That span is service conductors, and a fault there returns on the neutral. The NEC is blunt that the earth is not that path (NEC 250.4(A)(5)).
The neutral-ground bond lives at the service disconnect and nowhere downstream of it; why the neutral bond exists only at the service disconnect walks through the reason.
| Span | Conductors in it | Bonding |
|---|---|---|
| Meter can to first disconnect | two hots and the neutral | can bonded to the neutral; no EGC |
| Disconnect to a downstream subpanel | hots, neutral, EGC | neutral isolated; EGC per NEC Table 250.122 |
Where the grounding electrode conductor lands
The grounding electrode conductor may land at any accessible point on the supply-side neutral: the meter can, a gutter between can and panels, the first panel, or both panels through taps. Utility rules govern the meter itself. Some utilities refuse a grounding electrode conductor in the socket; some require a rod driven at the meter. One phone call settles it before you bend any wire.
Four landings that pass:
- Into the meter can, bonded to the neutral, where the utility allows it.
- Into one panel, tapped to the other. Run the conductor to the first panel, then tap to the second panel's neutral bus with a listed split bolt. Size each tap from the conductors at that disconnect, and the NEC lets a tap stay at 3 AWG copper even where the table reads larger.
- At an accessible splice in a gutter or listed box between can and panels, made with listed connectors.
- On a ground bar. A copper bar at least 1/4 in [6 mm] by 2 in [50 mm], bolted solidly to the wall, may interconnect grounding electrode conductors and bonding jumpers. The small terminal on the can for telephone and antenna grounds serves communications only; your power taps stay off it.
Keep every tap and splice accessible: inside the panels, a gutter, or a covered box, not behind drywall. Only the utility can make a meter can safe to open; the main breaker does not.
For the tap layout in detail, read one grounding electrode conductor on multiple service disconnects. For landing the conductor at the enclosure wall, read bonding a grounding electrode conductor to a service enclosure.
Sizing the conductor for a 400 amp split service with two 200 amp panels
The case behind this question: a 400 amp split service, a 320 amp meter can, two 200 amp main-breaker panels. Assume each panel is fed with a set of 2/0 copper SER, the size the NEC's 83% dwelling rule makes standard for a 200 amp panel. Swap in your actual conductor size and redo the two steps that depend on it.
Step 1 - check the service conductors. The NEC sizes dwelling service-entrance conductors at 83% of the service rating: 0.83 x 200 A = 166 A per panel. 2/0 copper carries 175 A at 75 C under the NEC's ampacity table for copper at 75 C, so 2/0 holds.
Step 2 - size the main grounding electrode conductor from the combined service conductors. One 2/0 is 133.1 kcmil, so two sets make 2 x 133.1 = 266.2 kcmil. The NEC's grounding electrode conductor table puts copper service conductors over 3/0 (167.8 kcmil) through 350 kcmil at 4 AWG copper. Result: 4 AWG copper from the electrodes to the first landing.
Step 3 - size each tap from its own disconnect. The largest conductor at each panel is 2/0 copper, and the table row for 1/0 through 3/0 copper reads 6 AWG. Result: a 6 AWG copper tap to each panel's neutral bus.
The decision for this case: run the Step 2 conductor from the electrode system to the meter can if the utility allows it. Without the utility's blessing, land it at the first panel instead. Tap each panel's neutral with the Step 3 tap size using listed split bolts. Bond the can. Keep neutrals and grounds common in both panels, and keep the 200 amp feeders to hots and neutral.
What moves the answer: a single set of 400 kcmil copper from the utility gives 0.83 x 400 A = 332 A against 335 A for 400 kcmil copper at 75 C, and drops the main conductor to 2 AWG copper. Aluminum conductors move every size two steps larger.
When the breakers live in the meter main
If the 320 amp meter main carries the two 200 amp breakers, the disconnects sit inside the can and the answer flips in three places.
- The neutral-ground bond and the grounding electrode conductor both land at the meter main. The tap question disappears.
- The 200 amp runs to the panels become feeders. Each one carries an equipment grounding conductor sized from its breaker per NEC Table 250.122 at 200 A.
- Your panels isolate neutral from ground the way any subpanel does; see removing a neutral ground bond in a downstream panel.
A qualified metal raceway can serve as that feeder EGC instead of a wire; metal conduit as the equipment grounding conductor covers when it counts. Watch one hazard: a second neutral bond downstream puts neutral current on the grounding system. On gear with transfer switching it also forces four-pole switching — why a second neutral bond forces four-pole breakers.
Bonding the enclosures around the service
On the load side, every metal enclosure bonds to the equipment grounding conductor through a listed hub or a bonding jumper (NEC 250.96(A)). Paint and other nonconductive coatings come off the contact points first (NEC 250.12). On a brushed stainless box that means scraping the finish back to bare metal under a listed grounding hub, fitting bonding washers, or running a jumper past the coating to the bar; the connector and bond at a grounding conductor's enclosure entry shows the hardware. The grounding and bonding guide carries the fundamentals for our boxes.
The meter socket and the main-breaker panels are listed service equipment. Our enclosures are manufacturer-rated NEMA 4X / IP66; not UL listed. That puts our boxes downstream: a bonded junction or pull point, a ground-bar enclosure, PV disconnect landings. Where chlorides rule the site, custom 316L enclosures cut every hub position you mark and shrug off salt air better than 304.
What to put on the order
| Item | Size to order | Basis |
|---|---|---|
| Main grounding electrode conductor | 4 AWG copper; 2 AWG for a single 400 kcmil copper set | Step 2, two sets of 2/0 copper |
| Tap to each 200 amp panel | 6 AWG copper | Step 3, table row for 1/0 through 3/0 copper at each disconnect |
| Feeder EGC, meter-main layout | sized from NEC Table 250.122 at 200 A | per its own breaker |
| Rod-to-rod bond | copper, the NEC cap for bonding electrodes to each other | NEC electrode bonding rule |
| Rod spacing | two rods 6 ft [1.8 m] apart | second rod unless one measures 25 ohms or less |
| Ground bar | copper, 1/4 in [6 mm] x 2 in [50 mm] | NEC rule for a bar joining electrode conductors |
| Downstream enclosure | bonded junction or ground-bar box, 316L in salt air | manufacturer-rated NEMA 4X / IP66; not UL listed |
For a stock-size start, 316L wall-mount enclosures run from 6 x 4 x 4 in to 60 x 36 x 16 in and take a ground bar and a hub.
Decide with one question: where are the breakers? In the panels: bond the can, land the grounding electrode conductor at the can or tap both panels off the Step 2 run with the Step 3 tap size, and keep the feeders to hots and neutral. In the meter main: bond and land everything at the main, isolate the panels, and send the Table 250.122 EGC down each 200 amp feeder. Either way the meter can bond stays, and the earth stays out of the fault path.
Catalog dimensions to compare
Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 20 × 16 × 8 in | 304 stainless | 20 x 16 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does a metal meter can always bond to the neutral?
Yes, whenever it sits ahead of the main breakers: the grounded conductor bonds to every metal enclosure it passes through on the supply side, and most 320 amp meter mains arrive with that bond made at the factory. If the utility hangs a nonmetallic can there is nothing to bond, so the grounding electrode conductor lands on the neutral somewhere else that stays accessible.
What size grounding electrode conductor does a 400 amp split service need?
For two sets of 2/0 copper service conductors, the sizing steps below give a 4 AWG copper run and a 6 AWG copper tap to each panel. The same conductors in aluminum mean two sizes larger on every one of them. One 400 kcmil aluminum set drops the main conductor to 1/0 aluminum.
Why is there no equipment grounding conductor between the meter and the first panel?
That run is service conductors, not a feeder: ahead of the main disconnects the bonded neutral is the fault path, and the earth itself never is. If the main breakers sit in the meter main, the 200 amp runs become feeders and each one carries an EGC sized from NEC Table 250.122 for its breaker.
Can the grounding electrode conductor land inside the meter can?
Often, but the utility owns that answer: some forbid a grounding electrode conductor in the socket and some require a rod driven at the meter. A rod at the meter is an auxiliary electrode under NEC 250.54; you may connect it, but it never replaces the conductor to the water pipe, building steel or rod system.
Can the panel taps land on the intersystem bonding terminal?
No. That terminal exists for communication grounds: telephone, coax, satellite dish and antenna. Power grounding electrode conductors and their taps land on the neutral, on listed split bolts, or on a copper bar at least 1/4 in by 2 in bolted to the wall. Bonding the electrodes themselves together takes a conductor no larger than 6 AWG copper.
