An OEM we work with shipped 400 outdoor EV chargers to southern Germany last fall with a hybrid cable-entry design: conduit for the AC input cables, cable glands for the DC and signal cables, all on the same chassis. After 6 months, 28 of the chargers came back with water inside the housing. The cause was not the conduit, not the gland, and not the gasket — it was the empty knockout holes. The foreman had punched M25 and M32 holes in the gland plate for future cable runs, but the production run did not use them. The holes had shipped with thin plastic knock-out plugs that survive indoor air but not a -15 °C winter night. Cold-brittle plastic, water ingress, electrolytic corrosion in three places. The fix: leave the metal sheet un-punched at unused positions (we punch on order, not on stock); specify a continuous rubber gasket under the gland plate, not a per-hole seal; and use the same cable gland series across the entire panel. The 28 chargers came back with one cable-gland plate each, costing €38/each in rework — €1,064 total, plus the cost of 28 field service calls.
This guide walks through the cable-entry trade-off that every industrial panel drawing eventually faces: conduit or cable gland. It is a question we answer several times a week, and the answer is almost always "both — choose by cable function." A well-designed enclosure mixes the two: conduit for fixed AC power and ground, cable glands for DC, signal, sensor, and field-wiring. The drawing must commit to that mix on the BOM, not at the assembly plant.
Why Both Still Exist — What Each Does
Conduit and cable gland are not the same thing, and they are not substitutes. Conduit is a continuous protective raceway — rigid metal, flexible metal, or PVC — that runs from one enclosure to another, carrying one or many wires inside. The conduit itself is the protection; the wires inside are not armored. Cable gland is a connector that mounts through one wall of the enclosure, sealing around a single cable as it passes through. The cable itself provides the insulation; the gland provides the strain relief and the environmental seal.
Three rules of thumb, in order of authority across OEM drawings:
- Code-mandated conduit. NEC Article 348 (rigid metal conduit, RMC), Article 350 (liquidtight flexible metal conduit, LFMC), Article 352 (PVC), and the IEC 61386 series require conduit for fixed wiring in many industrial, hazardous-location, and outdoor installations. The relevant clauses are NFPA 70 (NEC), IEC 60364 (international), and BS 7671 (UK).
- Gland-everywhere-else. For DC power distribution inside an OEM enclosure, sensor wiring, communication cables, and field-bus connections, cable glands are the OEM default. The relevant standards are EN 62444 / IEC 62444 (cable gland construction), EN 60529 (IP rating), UL 514B (US gland box), and CSA C22.2 No. 18.3 (Canadian gland).
- Hybrid panels. Large industrial enclosures routinely mix — a conduit entry for the main AC feed at the top, multiple gland entries on the bottom plate for sensor and signal. The BOM and the panel punch layout must specify both, not leave the choice to the field installer.
The most common mistake on hybrid panels: the drawing specifies "cable entry on bottom plate" without naming a series, leaving the assembler to choose a metric or NPT gland that does not fit the holes. Always specify the gland series (e.g., Lapp Skintop, Hummel HSK, or Pflitsch blueglobe) and the thread pitch on the drawing, not in the BOM comment. For an in-depth cable-gland material and selection guide, see our cable gland selection guide; for DIN rail and panel cutout discipline, see our DIN rail & panel cutout guide.
The 5-Row Conduit-vs-Gland Comparison
The trade-off across the five axes that matter most to OEM panel builders:
| Axis | Conduit | Cable gland | Why it matters |
|---|---|---|---|
| Mechanical protection | High — rigid conduit resists impact and crush; LFMC handles flex & vibration | None — relies on cable armor | Cable gland alone is wrong for any run exposed to physical impact |
| IP / NEMA rating | IP65–IP67 typical, with proper gaskets | IP65–IP68 (with appropriate compression) | Both can meet outdoor / wet ratings; gland dominates for sensor / signal |
| EMC / bonding | Excellent — bonded conduit raceway acts as extension of chassis | Requires EMC backshell (24° tapered, 360° shielded) — see our EMI shielding guide | Gland needs explicit EMC backshell for shielded cables |
| Re-entry | Easy — pull wires, replace, or add | Hard — every re-entry requires re-mounting the gland | Conduit dominates for service access; gland for one-shot termination |
| Hazardous area | Typically required (NEC 501.10, IEC 60079-14) | Allowed if Ex e / Ex d certified | Conduit dominates in NEC Class I Div 1; gland plus certified entry in ATEX/IECEx Zone 1 |
The pattern: conduit for fixed AC runs and any location exposed to physical or hazardous conditions; cable gland for DC, signal, sensor, and field-bus where the cable armor is its own protection. A 600 × 800 mm industrial panel typically has one conduit entry (the main AC feed) and 6–14 gland entries (DC distribution, signal, sensors). A 600 × 2000 mm telecom cabinet often has none (all fiber and DC arrive on pre-terminated cables with glands only) or four (gland for DC, conduit for AC service feed).
Choosing the Right Conduit Type
If conduit is the right call, the second question is the conduit type. The four in OEM use, in order of frequency:
- Rigid metal conduit (RMC, NEC 344 / IEC 61386-21). Heavy wall steel or aluminum. Forged or cast fittings. Used in utility, substation, heavy industrial, and any run exposed to physical impact. Most expensive, hardest to reconfigure.
- Intermediate metal conduit (IMC, NEC 342 / IEC 61386-21). Thinner wall than RMC, same steel. ~ 30% lighter, ~ 25% cheaper. Common in commercial and light-industrial OEM enclosures.
- Liquidtight flexible metal conduit (LFMC, NEC 350 / IEC 61386-23). Flexible, vinyl-jacketed. Used where the run moves or where vibration is constant — outdoor camera mounts, pump motors, robotics. The most common conduit at the OEM enclosure interface.
- PVC (PVC-40, PVC-80, NEC 352 / IEC 61386-21). Corrosion-resistant, non-conductive. Used in chemical, wastewater, and below-grade runs. Cannot serve as the equipment-grounding conductor; needs a separate grounding wire.
The OEM drawing should specify the conduit trade size (1/2", 3/4", 1", 1-1/4" in NPT, or M16, M20, M25, M32 in metric) and the fitting series (e.g., Crouse-Hinds, Appleton, or equivalent). Stainless fittings (Type 304 or 316) are mandatory for outdoor / chemical / coastal installations. For hazardous areas, both conduit and fittings must be certified — see our hazardous location guide.
Choosing the Right Cable Gland
Cable gland selection is its own topic — our cable gland selection guide covers material, IP rating, EMC backshells, and Ex certification in depth. The 90-second OEM rule is the following five-point decision:
- Material. Brass (nickel-plated) for indoor general industrial; stainless 316 for outdoor / coastal / food-grade; Nylon (PA6) for light commercial and DC-only indoor; aluminum for weight-critical. Brass is the default.
- Thread. Metric (M) for international, IEC-certified OEM; NPT for North American; PG is legacy (now superseded by metric). Specify thread pitch (M20 × 1.5, 1/2" NPT, etc.) on the drawing.
- IP rating. IP68 (1.5 m, 30 min) for outdoor and wet; IP66 for outdoor splash; IP65 for indoor washdown; IP54 for indoor general. Match the gland to the enclosure rating exactly — an IP65 gland in an IP67 plate fails the IP67 rating.
- EMC backshell. 360° shielded termination (Lapp Skintop MS-SC, Hummel HSK-MZ-EMV, Pflitsch blueglobe) for any shielded signal cable or any cable in an EMC-rated enclosure. The backshell bonds the cable shield to the gland body, which bonds to the enclosure wall at the wall, not inside. For the full EMC wiring story, see our EMI shielding guide.
- Strain relief. All glands to beclamp on the cable jacket, not the conductors. Specify "clamp on outer jacket, ≥ 100 N pull-out" on the drawing. A gland that grabs the inner insulation is a gland that has failed.
The 28 EV chargers that came back had no third category mistake. The gland plate design used a metric gland series (M25) but the gland plate itself was sized to a 1/2" NPT imperial specification — the assembler had to drill the holes oversized, and the wrong gasket landed in the wrong place. Always specify the gland series, thread pitch, and the gland-plate hole pattern on the same drawing note.
Panel Punch Layout — The Gland Plate Discipline
The gland plate is the removable panel that carries the cable entries. On industrial OEM enclosures the gland plate is its own removable part — usually 2.0 or 2.5 mm galvanized or stainless steel, gasketed to the chassis with a continuous rubber gasket (not per-hole) and bolted with M5 or M6 fasteners at 50 mm pitch. Three rules of layout:
- Group by function. Power entries on one row, signal on another, sensor/exhaust on a third. The grouping survives the installer's mistake of cross-wiring a signal cable over a power terminal.
- Center the cable runs in the hole. The cable must enter the gland perpendicular to the panel (± 5°). Off-axis cables wear the gasket and fatigue the cable.
- Punch on order. Stock gland plates with all possible positions pre-punched accumulate frozen plastic knock-out plugs in unused positions, which fail the IP rating the first winter. Punch on demand against the BOM.
The DFM mistake we see on every OEM re-quote is the same one — punched-and-plugged gland plates. The cost saving on stock SKUs is real (one part number for many configurations) but the field cost is also real. For OEM buyers who need stock flexibility without plug failures, the right move is a bonded-stock gland plate with rubber-gasket-only holes in common positions and blank plates laser-cut to the actual BOM.
7-Point DFM Checklist for Cable Entry
- Conduit vs gland callout on the drawing. Conduit for fixed AC and exposed runs; gland for DC / signal / sensor. Specify trade size or gland series plus thread pitch.
- Gland-plate is a removable part. Continuous rubber gasket under the plate, M5 / M6 fasteners at ≤ 50 mm pitch, 2.0–2.5 mm thick, galvanized or stainless. Punched to the BOM at order time, not at panel-stock time.
- Group entries by function. Power on one row, signal on another, sensor / exhaust on a third. Cross-wiring mistake catch.
- EMC backshell for every shielded cable in an EMC-rated enclosure. 360° termination to the gland body, bonded to the enclosure at the wall, not in the cabinet.
- Strain relief on the jacket. Specify "clamp on outer jacket, ≥ 100 N pull-out" — not on the conductors.
- Hazardous area note. Conduit for NEC Class I Div 1 / 2 by default. For ATEX / IECEx Zone 1, gland must be Ex e or Ex d certified (matching the certification of the enclosure — see hazardous location guide).
- Document the unused positions. No pre-punched knock-out holes. Unused positions blank until the BOM arrives.
Closing — One Note, Two Lists, One Gland Plate
Three lines on the drawing is enough to avoid 80% of the rework:
- "AC service feed: 3/4" LFMC (or M25) conduit, 316 stainless fitting, ground-bonded to chassis at the fitting. DC and signal: cable glands Lapp Skintop MS-SC (M20 × 1.5) series, EMC backshell, IP68, brass nickel-plated, bonded to panel via continuous 3 mm rubber gasket under the gland plate."
- "Strain relief: clamp on outer cable jacket, ≥ 100 N pull-out. No conductor clamping."
- "Gland plate: 2.5 mm galvanized steel, removable, continuous rubber gasket, M6 fasteners at 50 mm pitch. Punched to the BOM at order time."
Send the panel drawing and the cable schedule (which conductor types, which signals, which sensors) to SanJun. We will return a one-page Cable Entry Design Pack within 24 hours — gland plate layout, conduit vs gland assignment, EMC bonding scheme, and a fixed-price cable-entry line item. Use the contact form or email gongtianbao@xhlmarketing.com.