Short answer: yes. Sealtite — the shop name for liquidtight flexible metal conduit — is a permitted wiring method in a Class II, Division 2 location. The NEC lets Division 2 take every wiring method Division 1 allows and adds the general Chapter 3 methods, where both liquidtight flexes sit. The conduit is almost never what fails an inspection. The defects are around it: a general-purpose tee with an ungasketed cover, a knockout without a dust-tight hub, or a flex run with no bonding path. Fix those three on your run and it passes. This page sets out what the code asks of each piece, sizes the bonding jumper from the breaker ahead of it, and works one motor drop end to end.
What the code allows in Division 2
The NEC's Class II wiring rules, Article 502, split by division. Division 1 is where ignitable dust can show up under normal operation. Its list is short: threaded rigid metal conduit, threaded steel intermediate metal conduit, Type MI cable, and dust-ignitionproof boxes and fittings. Division 2 keeps that entire list and adds the general wiring methods of NEC Chapter 3 — the raceways and cables the rest of the plant runs every day. Liquidtight flexible metal conduit and liquidtight flexible nonmetallic conduit are both Chapter 3 methods, so your flex run in Division 2 is legal on its face. The current NEC text goes further and names EMT for Class II, Division 2 with compression-type fittings, and it specifically addresses coated RMC and IMC; that is how far the general permission reaches.
Division 1 holds the flex to the flexible-connection job — motor drops and vibrating equipment — with listed fittings. Division 2 opens it up as a general run, which is why a sealtite drop to every motor on a machine is a normal Division 2 detail. The trade wiring-method charts open their Division 2 column with any suitable wire or cable in threaded rigid metal conduit, then widen out to the cable types and both flexes.
| Wiring method | Class II, Division 1 | Class II, Division 2 |
|---|---|---|
| Threaded rigid metal conduit, threaded steel IMC | Yes | Yes |
| Type MI cable | Yes | Yes |
| Dust-ignitionproof boxes and fittings | Yes | Yes |
| EMT with compression-type fittings | No | Yes |
| Liquidtight flexible metal conduit (sealtite) | Flexible connections only, listed fittings | Yes — a general method, listed fittings |
| Liquidtight flexible nonmetallic conduit | Flexible connections only, listed fittings | Yes — a general method, listed fittings |
| Ungasketed general-purpose boxes and fittings | No | No — dust-tight versions required |
The last row applies to the whole run, not only to the boxes.
Why the fittings fail inspection, not the flex
Class II rules ask one thing of the hardware between the enclosures: keep the dust out. Boxes and fittings in the run must be dust-tight — a gasketed cover, a gasketed hub at every entry, a close-up plug in every unused opening. A general-purpose LB or tee has a plain screwed cover, and dust walks straight through the threads under it. The wireway counts too: close every gasketed cover and land the flex on gasketed end connectors. IEC 60529 calls this level dust-tight; its first digit 6 (IP6X) means dust may not enter, and the IP rating chart lays out the digits.
The same duty sits at each termination into the enclosure. Fit a gasketed hub or a dust-tight gland on every knockout you use, and plug the ones you leave spare. One open 1/2 in [13 mm] knockout sets the dust rating of the whole assembly, because the weakest opening in a run sets the rating for the run. The cutout and hub details that keep a NEMA 4X box sealed are laid out in the cutouts, glands and HMI windows guide.
The repair is small. Swap each general-purpose condulet for a dust-tight one with a gasketed cover, add gasketed hubs at the enclosure entries, and plug the spares. The flex, the wireway and the boxes usually stay exactly where they are. Sealing fittings are a Class I instrument, and Class II has none of that duty — the Class II Division 2 sealing page shows when no conduit seal is needed.
Bonding the flexible run
A flexible metal sheath is a spiral wrap, and you cannot count it as a fault-current path. NEC 250.96(A) requires raceways, enclosures and other metal parts to be bonded so they can safely carry any fault current likely to be imposed on them. Two builds meet that on your sealtite run: fittings listed for grounding and bonding, or an insulated bonding jumper run through the flex. Size the jumper from the rating of the overcurrent device ahead of the circuit, using NEC Table 250.122:
| Breaker ahead of the circuit | Copper bonding jumper (NEC Table 250.122) |
|---|---|
| 20 A | 12 AWG |
| 60 A | 10 AWG |
| 100 A | 8 AWG |
| 200 A | 6 AWG |
Run the jumper the full length of the flex and land it on the ground bus or a bonding screw at both ends. On painted carbon-steel boxes, NEC 250.12 calls for the coating to come off the threads and contact surfaces; stainless boxes have no coating, so the connection lands on bare metal as it arrives. The grounding and bonding guide covers the whole fault path. If the flex has no metal core, the Chapter 3 permission is unchanged but the sheath cannot help at all: the equipment grounding conductor inside carries the fault current, sized from the same table row. The jumper arithmetic follows the flex into the Class I articles too; the page on liquidtight conduit bonding in Class I Division 2 works those numbers end to end.
A motor drop that passes, worked end to end
Take a 5 hp, 460 V, three-phase motor in a Class II Division 2 area, fed from a gasketed stainless wireway overhead. The NEC motor full-load table lists 7.6 A for that motor. An inverse-time breaker on a motor branch lands at 250 % of full-load current: 7.6 A × 2.5 = 19 A, and the next standard size up makes it a 20 A breaker. The bonding jumper then reads straight off the 20 A row of NEC Table 250.122: 12 AWG copper.
Your hardware list is short: 4 ft [1.2 m] of 3/4 in [metric designator 21] liquidtight flexible metal conduit with listed fittings at both ends. Add one gasketed hub into the wireway and a gasketed connection at the motor terminal box. Inside the flex, run three 12 AWG copper phase conductors plus the 12 AWG jumper. The NEC conduit-fill values put a 12 AWG THHN conductor at 0.0133 in² and a 3/4 in raceway at 0.085 in² of allowed area at the 40 % fill used for three or more conductors. Four conductors take 4 × 0.0133 = 0.053 in², so the fill passes with about 0.03 in² to spare.
The same drop built with two general-purpose tees in the middle is the item an inspection report lists — never the conduit. Swapping the tees for dust-tight ones is about an hour of rework with the conductors pulled back. Re-pulling threaded rigid conduit to every motor costs days.
What it means for the boxes in the run
In Division 2 the enclosure's job is construction: gaskets that hold dust out, doors that compress them, and cutouts that land on dust-tight hubs. That is the part we build. Our wall-mount and custom enclosures are hinged stainless boxes with a gasketed door, a removable mounting panel and wall-mount feet, from 6 x 4 x 4 in up to 60 x 36 x 16 in (H x W x D), in 304 or 316L stainless — see the wall-mount range or send your own size to the custom builder.
A 12 x 12 x 6 in [300 x 300 x 150 mm] box is a normal junction point for a control circuit and its 12 AWG bonding path, as a 12 x 12 x 6 in 304 stainless wall-mount enclosure or the same box in 316L where the dust is corrosive. Every box is rated NEMA 4X / IP66 by the manufacturer; not UL listed — and IP66's first digit 6 is the dust-tight level of IEC 60529, so the gasket set that passes the hose test holds the dust as well. Your cutout drawing goes in as-is and the finished box is delivered in 10 business days, counted from your approval of the drawing.
The marking side belongs on the drawing too. For a US installation, NEC 110.28 makes the enclosure Type the marking the code reads, and Table 110.28 lists which Types suit Class II, Division 2 — so write that Type on the panel drawing. A finished assembly is an industrial control panel under NEC Article 409, and UL 508A is the standard that lists one. NEC 409.110 also requires the enclosure type number on the panel marking; the UL 508A listing guide walks that path. Dust-ignitionproof Division 1 enclosures are not enclosures we build; Division 2 asks for dust exclusion, and the gasketed build provides it. The Class II Division 2 enclosure selection page walks the dust-tight marking question in full.
The decision, case by case
- Flex to a motor or vibrating device, Class II Division 2, fed from a dust-tight wireway: keep it. Listed fittings at both ends, gasketed hubs, and a bonding path — 12 AWG copper on the 20 A motor branch above.
- General-purpose tees or LBs already installed in Division 2: replace them with dust-tight condulets with gasketed covers. The sealtite stays.
- The area is Class II Division 1: the Chapter 3 general methods drop away. Threaded rigid metal conduit or threaded IMC carries the circuits, with the flexible-connection allowance at motors.
- The area is Class I: a different article and different rules — the Class I Division 1 conduit and gland guide covers the wiring methods and their seals.
- Spec line for the order: liquidtight flexible metal conduit with listed fittings; dust-tight boxes, fittings and hubs throughout; bonding per NEC 250.96(A) with jumpers sized from NEC Table 250.122.
Questions
Is sealtite permitted in Class II Division 2?
Yes. The NEC lets Division 2 use every wiring method Division 1 allows plus the Chapter 3 general methods, and liquidtight flexible metal conduit is one of them. Terminate it in listed fittings, keep every box, hub and plug dust-tight, and carry a bonding path. A 20 A branch circuit needs a 12 AWG copper jumper under NEC Table 250.122 when the fittings are not marked for bonding.
Do Class II Division 2 conduit runs need sealing fittings?
No. Sealing fittings stop vapor migration in Class I areas, and dust cannot migrate through a raceway the way gas does, so the Class II rules ask for dust-tight boxes and fittings instead of seals. A typical machine retrofit means 0 sealing fittings and a gasketed cover on every junction point. The Class II sealing page shows when no conduit seal is needed.
What size bonding jumper does a sealtite run need?
Size it from the overcurrent device ahead of the circuit, per NEC Table 250.122: a 20 A device needs 12 AWG copper, 60 A needs 10 AWG, 100 A needs 8 AWG and 200 A needs 6 AWG. Fittings listed for grounding and bonding can replace the jumper when they carry the bonding rating.
What enclosure rating works in a Class II Division 2 area?
Dust-tight: dust may not enter, the level IEC 60529 describes with first digit 6. Our gasketed stainless boxes are manufacturer-rated NEMA 4X / IP66, not UL listed, and a 12 x 12 x 6 in box is a normal junction point for a control circuit. The finished panel's classified-location listing under UL 508A is a separate step that belongs to the panel builder.
Why did a general-purpose condulet fail inspection in Division 2?
The Class II rules want boxes and fittings dust-tight. A general-purpose LB or tee has an ungasketed cover, so dust passes the threads under it. Swap each one for a dust-tight version with a gasketed cover and gasketed hubs — about 20 minutes per fitting with the conductors pulled back — and keep the flexible conduit; the flex was never the defect.
