Short answer: yes — the metal raceway is the equipment grounding conductor (EGC), and the cabinet joins that path at two bonds you make. A listed bonding hub where the conduit lands and the ground bar's supplied bonding screw put the wall between bar and raceway. With both in place, fault current runs from the bar, through the wall, out the hub and down the raceway, with no supplemental wire ground. The enclosure itself is neither a bonding jumper nor the EGC; it is bonded equipment, and only your two connections make it one. The raceway type, the knockout, the paint and the hub decide the job, and this is what each needs.
Where the fault current actually flows
A ground fault on a branch circuit reaches that circuit's ground terminal and lands on the panelboard's ground bar. From there it needs metal all the way back to the source. NEC 250.4(A)(5) calls this the effective ground-fault current path and rules the earth out of it. In your arrangement the path is the bar, the bonding screw, the cabinet wall between screw and hub, the hub, then the raceway run.
The wall segment carries real fault current for the few inches between those points, and the code plans for it. NEC 250.96(A) requires raceways, cables, equipment and enclosures that serve as grounding conductors to be bonded together so they can safely conduct the fault current likely to be imposed. So the enclosure becomes an extension of the EGC once both bonds exist, and it contributes nothing before them. Keep the segment bare and short: a bar 10 in from the hub in a 30 in wide cabinet leaves about 15 in of wall in the path, and two painted standoffs can strangle that where bare steel barely notices. The enclosure grounding and bonding guide carries the fundamentals, and ground bar placement: enclosure wall vs mounting plate covers where the bar itself belongs.
What the raceway has to be first
The raceway earns its role by type, and the code does the arithmetic for you. Article 250 lists the conductors and raceways permitted as the EGC: wire-type grounds, rigid metal conduit, intermediate metal conduit and electrical metallic tubing among them. The test documents behind steel conduit and EMT show a raceway carrying the fault currents a table-sized wire must survive, so a trade size 3 run qualifies at any ampacity you feed it. Flexible metal conduit qualifies only within the code's length and fitting conditions; past them, pull a wire ground alongside.
For comparison, NEC Table 250.122 sizes a wire EGC from the rating of the overcurrent device ahead of it. At 200 A that wire is 6 AWG copper: 26,240 circular mils × 0.0005067 mm²/CM = 13.3 mm². At 400 A it is 3 AWG copper: 52,620 circular mils = 26.7 mm². The raceway replaces that wire outright. A PVC or other nonmetallic run is off the list, so the wire comes back: pull 6 AWG copper for a 200 A device, bond it bar-to-source, and seal the entry — a Myers hub with PVC conduit covers the sealing question. Parallel runs each take a full-size wire ground when you use wire at all, and each metal raceway bonds at both ends.
The three connections that decide the job
| Connection | Hardware that passes | What the code or the listing asks |
|---|---|---|
| Raceway to cabinet | Listed bonding hub or bonding locknut at the conduit's trade size; a standard hub with double locknuts on a solid knockout at 120/208 V | NEC 250.96(A) bond; NEC 250.12 coating off the contact faces unless the fitting is designed for coated walls |
| Knockout | Solid cutout, or a listed bonding device around a concentric or eccentric ring | Bonding around the hole on systems over 250 V to ground |
| Ground bar to cabinet | The supplied bonding screw or strap, thread biting bare metal | The panelboard's listing and its instructions; NEC 250.12 at the screw |
Work the connections with the panel dead and verified.
A listed bonding hub clamps the conduit to the wall with its own bonding means, so one part covers coated steel, eccentric rings and the inspector's questions. Choose it whenever the raceway is the EGC. The choice among hub styles and weather sealing is its own question: conduit hub vs sealing locknut for outdoor top entries sorts the options, and which listed conduit hubs pass at service equipment names the heavy-duty ones. Trade-size knockouts on a listed enclosure follow UL 50 Table 71-1A; on a custom cabinet you put the solid cutout on the drawing instead.
Concentric and eccentric knockouts carry raised dimples that hold the conduit off bare metal. Above 250 V to ground the NEC requires bonding around those holes, by a bonding jumper through them or a listed bonding locknut. A 120/208 V panelboard sits below that line, where a solid knockout with a hub needs nothing extra. Bonding a rigid conduit through an eccentric knockout walks the jumper sizing if your hole is already cut.
The bar bond is the one panelboard makers write into the instructions: bond the equipment terminal bar to the enclosure, and land every equipment ground on the bar. The supplied screw or strap does it, provided the thread cuts into bare metal rather than paint. Bonding the ground bus to a subpanel enclosure with the supplied screw covers that sequence, and enclosure grounding screw threads and lug fit covers what the thread has to bite.
What is tested and what is not
A listed panelboard ships as a listed assembly: interior, cabinet and the bonding hardware between them, evaluated together to UL 67, with the instructions standing in for the listing's conditions. In US workplaces OSHA 1910.303(a) requires approved electrical equipment, and 1910.399 defines acceptable as listed, labeled or otherwise determined safe by a nationally recognized testing laboratory. The raceway, the hub and the bonding locknut are listed articles in their own right.
Your field work is what nobody tests: the paint left under a plain locknut, a thread that stopped after two turns, standoff washers that leave the bar floating. A cabinet you build or rework outside the factory is no longer that listed assembly either. Our stainless enclosures are rated NEMA 4X / IP66 by the manufacturer; not UL listed — and a NEMA type describes water and corrosion, never fault current. When a project needs a listed panel in a cabinet built to order, how inspectors treat an unlisted box around a listed panel sets out the route, and UL 50E vs NEMA 250: listed or manufacturer-rated? separates the two kinds of rating.
A 200 A panelboard in an EMT riser, worked through
Take a 208Y/120 V panelboard with a 200 A main, fed by three 4/0 AWG THHN copper conductors in a trade size 3 in EMT riser that enters the cabinet bottom. Walk it in order:
- Raceway type. EMT is on the permitted list, so the raceway is the ground and no wire EGC rides the conduit.
- Wire equivalent. At 200 A the table wire would be 6 AWG copper: 26,240 circular mils × 0.0005067 mm²/CM = 13.3 mm². The EMT replaces it by listing; you compute nothing further.
- Knockout. Call out a solid cutout in the bottom wall at the conduit's trade size. At 120 V to ground the system sits under the 250 V line, and a solid hole with a listed hub passes with no bonding ring.
- Paint. 304 stainless is bare, so nothing strips. The same cabinet in powder-coated steel would need the coating off the hub faces under NEC 250.12, or a fitting designed for coated walls.
- Bar bond. Land the supplied bonding screw through its standoff into bare wall, and leave about 3 in below the cabinet for the hub body and locknut.
The finished path is branch EGC, bar, screw, wall, hub, EMT. A 36 x 30 x 12 in 304 stainless wall-mount enclosure holds that class of chassis with a short wall segment between screw and hub; specifying 316L changes nothing electrical.
What to put on the drawing and the order
On the drawing: the hub trade size and position, a solid knockout, a note that contact faces stay bare, the bar location with its bonding screw, and the clearance under the box for the hub body. On the electrical side, keep splices and taps inside NEC 312.8, which limits how much of a cabinet the conductors, splices and taps may fill; NEC 312.8 panelboard-as-raceway rules go through that limit line by line.
When the cabinet is ours, you set the material, width, height and depth and every cutout, from one piece, delivered in 10 business days from drawing approval. The 36 x 30 x 12 in box suits a small chassis. The largest stock wall-mount box is the 60 x 36 x 16 in 304 stainless enclosure; bigger cabinets come off the custom enclosure line, and the wall-mount range covers the rest.
Enclosures in this article
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 36 × 30 × 12 in | 304 stainless | 36 x 30 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 60 × 36 × 16 in | 304 stainless | 60 x 36 x 16 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does a 400 A feeder change any of the bonding hardware?
Only the wire-equivalent grows. The hub stays at the conduit's trade size and the bar bond stays the supplied screw. NEC Table 250.122 raises the wire-type EGC from 6 AWG copper at 200 A to 3 AWG copper, 52,620 circular mils (26.7 mm²), at 400 A. Steel conduit and EMT carry that fault current at any trade size, so the raceway still replaces the wire outright.
Can a PVC run share the same cabinet?
A PVC or other nonmetallic raceway is off the code's permitted-EGC list, so a wire ground rides the conduit: 6 AWG copper for a 200 A device per NEC Table 250.122, bonded bar-to-source. The enclosure still joins through the supplied screw to that wire, and a listed sealing hub keeps the nonmetallic entry weathertight.
Is the supplied bonding screw still needed with a listed bonding hub?
Yes. The listed hub bonds the raceway to the cabinet wall; the supplied screw bonds the ground bar and the chassis to that wall. Skip the screw and the bar sits on painted standoffs, so a branch-circuit fault has no metal route from bar to raceway. Both parts ship with the panelboard, and the screw takes one wrench.
What changes with two raceways run in parallel?
Each parallel raceway bonds at both ends and serves as its own permitted EGC. If you run wire grounds instead, every raceway carries a full-size conductor — 6 AWG copper each for a 200 A device, never a halved or shared wire. Each conduit still lands on a listed bonding hub on bare metal, and the bar bond stays the same.
