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Brass Conduit Plugs, Brass Slotted Plugs – Nickel Plated Metric, PG and NPT Thread
Brass Conduit Plugs – Nickel Plated Brass Slotted Plugs (Metric, PG & NPT Threads)
Brass Conduit Plugs (also called Brass Slotted Plugs, Brass Blanking Plugs, or Conduit Sealing Plugs) are threaded brass plugs with a milled screwdriver slot on the head face and a full external thread body, used to seal and blank-off unused conduit entry holes, cable gland knockouts, and tapped holes in electrical enclosures, junction boxes, distribution boards, motor terminal boxes, and control panels. Manufactured by Electrical Accessories India, these nickel plated brass slotted plugs are produced from free-machining CW614N brass (CuZn39Pb3 / C36000) on CNC automatic screw machines and finished with a uniform bright electroplated nickel coating for enhanced corrosion resistance, aesthetic finish, and conductivity for EMC earthing continuity. Available in three international thread standards — Metric (M-thread, M16 to M63), PG thread (PG7 to PG48, DIN 40430), and NPT thread (1/8″ to 2″) — these plugs are designed as direct-fit sealing elements for the corresponding cable gland, conduit fitting, and thread adapter ranges.
Product Overview
What Are Brass Slotted Conduit Plugs?
A brass conduit plug is a solid (non-hollow) or thin-walled threaded body with a hexagonal or circular head, featuring a single milled slot across the top face to accept a flat-blade screwdriver for installation and removal. The external thread engages directly with the tapped hole in an enclosure entry, a gland plate aperture, or an unused cable gland thread, providing a mechanical seal against dust, accidental contact, and in protected versions, water ingress. The slot design — as opposed to a hexagonal socket (Allen key) drive — is the industry-standard configuration for conduit plugs, enabling installation in confined spaces using a standard flat screwdriver. The slot depth and width are engineered to provide positive tool engagement without deforming under typical installation torque (2–12 N·m depending on thread size). On the opposing face (thread end), the full external thread engages with the female thread of the enclosure entry or gland plate over the thread length specified per the applicable thread standard (DIN 40430 for PG, IEC 60423/ISO 228-1 for metric, ASME B1.20.1 for NPT).
Nickel Plated Brass – Material and Finish Specification
The base material is free-machining brass to EN 12164 CW614N (equivalent to DIN CuZn39Pb3, BS CZ121, ASTM C36000 / CDA 360), the benchmark alloy for high-volume screw machine production of conduit fittings, cable gland bodies, and electrical hardware. CW614N provides machinability of 100% (CDA scale), tensile strength 340–430 MPa, hardness 55–80 HRB, and electrical conductivity of 26–28% IACS — fully adequate for earthing continuity between enclosure walls through metal conduit systems. The nickel plating (5–12 µm electrolytic bright nickel per ASTM B689 / EN ISO 4526) is applied over a copper strike (2–5 µm) for adhesion, producing a bright silver-white finish that is visually distinct from unplated brass or zinc die-cast alternatives, provides 400–600 hours salt-fog resistance (ASTM B117), resists tarnishing and oxidation in industrial atmospheres, and meets the aesthetic requirements of IEC 60947, IEC 61439, and BS EN 60529 panel builder specifications.
Metric Thread Conduit Plugs (M-Thread Slotted Plugs)
Metric thread conduit plugs are produced to IEC 60423 and EN 50262 thread form and engagement specifications. The metric thread series covered — M16×1.5, M20×1.5, M25×1.5, M32×1.5, M40×1.5, M50×1.5, M63×1.5 — directly corresponds to the standard metric cable gland thread series used across European, Middle Eastern, Australian, and Asian electrical installation practice. Plug head diameter and thickness are matched to provide a flush or sub-flush fit in standard 1.5–2.0 mm steel enclosure gland plates, avoiding protruding heads that could foul cable runs or door seals. Thread tolerance is 6g (ISO 965-1), gauged 100% with calibrated GO/NO-GO plug gauges before dispatch. For enclosures requiring IP sealing of blanked entries, a nitrile or EPDM O-ring or sealing washer (supplied separately or as part of a kit) can be fitted under the plug head to achieve IP54 or IP65 ratings at the plug location.
PG Thread Conduit Plugs (Panzergewinde Slotted Plugs)
PG (Panzergewinde / Conduit Thread) plugs comply with DIN 40430 thread form, which defines a round thread with a 80° flank angle, specific pitch and diameter for each PG size. The PG thread series covered — PG7, PG9, PG11, PG13.5, PG16, PG21, PG29, PG36, PG42, PG48 — matches the standard cable gland, conduit fitting, and enclosure knockout dimensions used in German, Italian, French, and wider European panel building traditions. PG thread plugs are the sealing element of choice for existing panel builders using PG-type cable glands (Lapp SKINTOP, Pflitsch, Hummel, Roxtec PG-compatible systems) who require a matching blanking plug to seal unused entries without thread adapters. Thread engagement length and pitch per DIN 40430 is verified by ring gauge inspection. PG plugs are available in nickel plated brass as standard; unplated brass or stainless steel alternatives are available on request for specialist applications.
NPT Thread Conduit Plugs (National Pipe Taper Slotted Plugs)
NPT (National Pipe Taper) conduit plugs conform to ASME B1.20.1 thread form with the standard taper of 1:16 (3/4 inch per foot), providing a pressure-tight interference fit when tightened without sealant on dry service applications. NPT sizes covered — 1/8″, 1/4″, 3/8″, 1/2″, 3/4″, 1″, 1-1/4″, 1-1/2″, 2″ — directly match the threaded conduit entry sizes used in North American NEC (NFPA 70), Canadian CEC, and international projects specifying US-standard electrical conduit systems (EMT, IMC, RMC). For conduit sealing applications requiring liquid-tight integrity, thread sealant tape (PTFE) or thread compound (Loctite 577 or equivalent) is applied to the NPT thread before installation. NPT conduit plugs are also used in industrial control panels, motor terminal boxes, explosion-proof (Ex d) enclosures to IEC 60079-1/UL 1203, and hazardous area junction boxes where unused threaded entries must be sealed with certified metallic plugs rather than plastic bungs.
Design Features – Slot, Head, and Thread Geometry
The screwdriver slot on each conduit plug is precision-milled to provide positive engagement without slipping during installation. Slot width and depth conform to ISO 4757 (screwdriver blade engagement) guidelines for the plug diameter. The head face is flat and smooth for flush seating against the gland plate surface, and the underside of the head (bearing face) is machined square to the thread axis for even torque distribution and positive seating without rocking. Thread run-out at the thread-to-head junction is provided to prevent bottoming-out before head face contact with the gland plate. For nickel plated plugs, the slot edges and head face are plated after machining, providing full corrosion protection at the most exposed surfaces. Plugs are 100% thread-gauged and dimensionally verified before shipment in bulk packaging with lot identification for traceability.
Applications in Electrical Installations
Brass nickel plated slotted conduit plugs are installed wherever a conduit entry hole, cable gland tapped hole, or knockout in an electrical enclosure is not used in the current installation phase but requires a metallic, code-compliant seal. Applications include: unused entries in steel distribution boards (DB), motor control centres (MCC), and power control centres (PCC); spare conduit entry knockouts in junction boxes, pull boxes, and handhole boxes; unused entries in terminal boxes on motors, pumps, and HVAC equipment; NPT-threaded unused entries in explosion-proof and flameproof (Ex d, IECEx/ATEX) enclosures where plastic plugs are not acceptable; spare entries in outdoor weatherproof enclosures (IP54, IP65, IP66) where metal-to-metal sealing preserves IP rating integrity; and unused cable gland apertures in switchgear, bus duct enclosures, and instrumentation panels during commissioning, before final cable routes are confirmed.
Conduit System Compatibility
These brass slotted plugs are dimensionally compatible with the corresponding Electrical Accessories India conduit fitting range, including Conduit Bushes Brass, Brass Lock Nuts Nickel Plated, Brass Thread Adapters and Enlargers, Brass Conduit Thread Reducer Bushes, Flexible Conduit Adapters, Flexible Conduit Fixed Connectors, and Flexible Conduit Swivel Connectors. Specifying conduit plugs from the same manufacturer as the cable gland and fitting range ensures thread compatibility, consistent finish, and a unified documentation package for project QA.
Pricing
Nickel Plated Brass Conduit Plugs (Slotted): US$ 11.50/kilogram (subject to thread type, size mix, order quantity, and packaging requirements. MOQ: 50 kg. Volume pricing available for annual contracts ≥500 kg. Individual piece pricing and mixed-size box packaging available for distributor orders.)
Key Features
- Free-machining CW614N brass (CuZn39Pb3 / C36000) base material – dimensional precision and long tool life
- Bright electroplated nickel finish (5–12 µm) – superior corrosion resistance vs. unplated brass
- Single milled screwdriver slot – standard flat-blade tool installation in confined spaces
- Available in three thread standards: Metric (M16–M63), PG (PG7–PG48), NPT (1/8″–2″)
- 100% thread-gauged with calibrated GO/NO-GO gauges before dispatch
- Electrically conductive – maintains EMC/earthing continuity in metal conduit systems
- Supplied in bulk or mixed-size kit packaging for panel builders and distributors
- Compatible with O-ring or sealing washer for IP54/IP65 sealed applications
Thread Precision and Gauge Compliance
All conduit plugs are threaded on CNC automatic screw machines with thread-rolling or thread-cutting tools producing threads to tolerance class 6g (metric, ISO 965-1), DIN 40430 specification (PG), and 2A (NPT, ASME B1.20.1). Thread gauging with calibrated ring gauges (GO gauge to verify form and diameter, NO-GO gauge to confirm no oversize) is performed on a sampling basis per ISO 2859-1 AQL 1.0 for dimensional-critical thread dimensions. Full-form thread rolling (on metric plugs where applicable) produces work-hardened thread flanks with superior fatigue resistance compared to cut threads, and eliminates sharp burrs that could damage enclosure thread inserts during installation. Thread engagement length per IEC 60423 (metric) and DIN 40430 (PG) requirements is verified on first-article samples using thread depth gauges.
Nickel Plating Quality and Adhesion
The electrolytic nickel plating process used for conduit plugs involves: alkaline degreasing and ultrasonic cleaning to remove machining oil and metal fines; acid activation (10% sulfuric acid, 30 seconds) to remove oxide layer and activate the brass surface; copper strike plating (2–5 µm, alkaline copper, ASTM B734) for improved adhesion between brass substrate and nickel deposit; bright nickel plating (5–12 µm, Watts nickel bath with brightener, ASTM B689, EN ISO 4526); and final water rinse and hot-air drying. Plating thickness is verified by XRF (X-ray fluorescence) on a sampling basis. Adhesion is tested by bend test (ASTM B571 Method 2) and thermal shock test (ASTM B571 Method 6) on sample pieces from each production batch. Salt spray resistance is verified by ASTM B117 test for 400+ hours without red rust on finished plugs from periodic batch testing.
EMC and Earthing Continuity
In metal conduit systems designed to provide EMC shielding continuity and equipotential bonding between conduit sections and enclosures, metallic conduit plugs (brass nickel plated) maintain electrical continuity at unused entries without breaking the Faraday cage effect of the metal enclosure. The nickel plating provides a low-contact-resistance surface (contact resistance <10 mΩ between plug head and gland plate measured per IEC 60512-2-2) compared to painted or anodized surfaces, ensuring the plug contributes to rather than interrupts the EMC integrity of the installation. For ATEX and IECEx explosion-proof enclosures to IEC 60079-1, metallic plugs (brass, stainless steel, or other approved metals) are mandatory for unused entries — plastic bungs are not acceptable as they cannot maintain the flameproof joint integrity required by the Ex d protection concept.
IP Rating Contribution
Brass conduit plugs, when correctly torqued into enclosure entries, contribute to the IP (Ingress Protection) rating of the enclosure at the entry point. A metallic plug installed metal-to-metal into a tapped enclosure entry provides IP20 (finger protection) as a minimum. With the addition of a polyamide or EPDM sealing washer under the plug head (available as accessory), IP54 (dust and splash-water protection) is achievable at the plug entry point. For IP65 and IP66 rated enclosures, a profiled elastomeric O-ring seated in a countersunk groove or a thread sealant (PTFE tape or thread compound) on NPT taper threads is required; the plug must be torqued to the sealant manufacturer’s specified torque to achieve the rated IP seal. Our application engineering team can advise on sealing washer specification and torque values for specific IP rating requirements.
ATEX and Explosion-Proof Applications
For use in ATEX Zone 1, Zone 2 (Gas), Zone 21, Zone 22 (Dust) hazardous area enclosures certified as Ex d (flameproof) per IEC 60079-1, unused cable entry threads must be sealed with metallic plugs that maintain the flame path integrity of the threaded joint. Brass nickel plated slotted plugs in metric and NPT thread are suitable for use as Ex d blanking plugs when the thread engagement and joint geometry meet the requirements of IEC 60079-1 Clause 5.2 (flameproof joints – threaded joints: minimum 5 full threads engagement). Customers specifying plugs for ATEX Ex d applications should confirm thread engagement against the enclosure manufacturer’s certified plug thread engagement specification. Electrical Accessories India can supply plugs with specific thread engagement lengths for ATEX-certified enclosures on request, with EN 10204 2.2 material certificates confirming brass composition.
Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Base Material | Free-machining brass CW614N / CuZn39Pb3 / C36000 | EN 12164 / ASTM B16 |
| Surface Finish | Bright electrolytic nickel plating | ASTM B689 / EN ISO 4526 |
| Nickel Thickness | 5–12 µm over Cu strike 2–5 µm | XRF verified |
| Drive Feature | Single milled screwdriver slot, ISO 4757 compatible | – |
| Head Type | Flat head, flush or sub-flush installation | – |
| Thread Form – Metric | M16, M20, M25, M32, M40, M50, M63 × 1.5 pitch | IEC 60423 / EN 50262 |
| Thread Tolerance – Metric | 6g (ISO 965-1) | GO/NO-GO gauged |
| Thread Form – PG | PG7, PG9, PG11, PG13.5, PG16, PG21, PG29, PG36, PG42, PG48 | DIN 40430 |
| Thread Form – NPT | 1/8″, 1/4″, 3/8″, 1/2″, 3/4″, 1″, 1-1/4″, 1-1/2″, 2″ | ASME B1.20.1 |
| Thread Tolerance – NPT | 2A (ASME B1.20.1) | Ring gauge verified |
| Tensile Strength (base) | 340–430 MPa (CW614N brass) | ASTM E8 |
| Hardness (base) | 55–80 HRB (CW614N brass) | ASTM E18 |
| Electrical Conductivity | 26–28% IACS (brass base) | ASTM B193 |
| Salt Spray Resistance | 400+ hours (ASTM B117) – no red rust | Batch testing |
| Operating Temperature | –40°C to +120°C | – |
| IP Rating (installed) | IP20 (bare) / IP54 with sealing washer / IP65 with O-ring or sealant | IEC 60529 |
| Packing | Bulk polybag (500–2000 pcs/bag), mixed kit boxes, or cardboard trays | – |
Thread Size Reference Tables
Metric Thread Conduit Plugs – Dimensions
| Thread Size | Thread OD (mm) | Pitch (mm) | Head Dia (mm, approx) | Overall Length (mm, approx) | Slot Width (mm) |
|---|---|---|---|---|---|
| M16 × 1.5 | 16.0 | 1.5 | 22 | 10–12 | 1.2 |
| M20 × 1.5 | 20.0 | 1.5 | 27 | 12–14 | 1.5 |
| M25 × 1.5 | 25.0 | 1.5 | 33 | 14–16 | 1.8 |
| M32 × 1.5 | 32.0 | 1.5 | 40 | 16–18 | 2.0 |
| M40 × 1.5 | 40.0 | 1.5 | 50 | 18–20 | 2.5 |
| M50 × 1.5 | 50.0 | 1.5 | 60 | 20–23 | 3.0 |
| M63 × 1.5 | 63.0 | 1.5 | 75 | 22–26 | 3.5 |
PG Thread Conduit Plugs – Dimensions (DIN 40430)
| PG Size | Thread OD (mm) | Pitch (mm) | Head Dia (mm, approx) | Overall Length (mm, approx) |
|---|---|---|---|---|
| PG 7 | 12.5 | 1.27 | 18 | 8–10 |
| PG 9 | 15.2 | 1.41 | 21 | 9–11 |
| PG 11 | 18.6 | 1.41 | 25 | 10–12 |
| PG 13.5 | 20.4 | 1.41 | 27 | 11–13 |
| PG 16 | 22.5 | 1.41 | 30 | 12–14 |
| PG 21 | 28.3 | 1.41 | 36 | 14–16 |
| PG 29 | 37.0 | 1.41 | 46 | 16–18 |
| PG 36 | 47.0 | 1.41 | 57 | 18–20 |
| PG 42 | 54.0 | 1.41 | 64 | 20–22 |
| PG 48 | 59.3 | 1.41 | 70 | 21–24 |
NPT Thread Conduit Plugs – Dimensions (ASME B1.20.1)
| NPT Size | Nominal Pipe Size | Thread OD at Entry (mm) | Threads Per Inch (TPI) | Head Dia (mm, approx) |
|---|---|---|---|---|
| 1/8″ NPT | DN6 | 10.3 | 27 | 16 |
| 1/4″ NPT | DN8 | 13.7 | 18 | 20 |
| 3/8″ NPT | DN10 | 17.1 | 18 | 24 |
| 1/2″ NPT | DN15 | 21.3 | 14 | 29 |
| 3/4″ NPT | DN20 | 26.7 | 14 | 35 |
| 1″ NPT | DN25 | 33.4 | 11.5 | 43 |
| 1-1/4″ NPT | DN32 | 42.2 | 11.5 | 53 |
| 1-1/2″ NPT | DN40 | 48.3 | 11.5 | 60 |
| 2″ NPT | DN50 | 60.3 | 11.5 | 73 |
International Equivalent Designations
| Standard / Region | Designation | Notes |
|---|---|---|
| IEC / ISO (Metric) | Conduit plug M16–M63, IEC 60423 | Standard in Europe, Middle East, Asia-Pacific, India |
| DIN (PG Thread) | Verschlussstopfen PG7–PG48, DIN 40430 | Older European standard; widely used in Germany, Italy, France |
| ANSI/NEMA (NPT) | Conduit plug 1/2″–2″ NPT, ANSI B1.20.1 | North America (NEC), Middle East oil & gas, export projects |
| BS (UK) | Conduit plug BS 31 (obsolete) / IEC 60423 current | UK metric conduit thread; PG and IEC metric both used |
| AS/NZS (Australia) | Conduit plug M20–M63, AS/NZS 2053 | Metric thread; Australian installations follow IEC 60423 |
| IS (India) | Conduit plug IS 2667 / IEC 60423 metric | Metric thread standard; PG also widely used from import |
| GOST (Russia/CIS) | Заглушка резьбовая PG / M-thread | PG thread widely used in legacy Russian electrical installations |
Product Variants and Ordering Options
| Variant | Description | Available Sizes | Finish |
|---|---|---|---|
| Metric Slotted Plug – Standard | Flat head, single slot, metric thread 1.5 pitch | M16, M20, M25, M32, M40, M50, M63 | Nickel plated |
| PG Slotted Plug – Standard | Flat head, single slot, DIN 40430 PG thread | PG7, PG9, PG11, PG13.5, PG16, PG21, PG29, PG36, PG42, PG48 | Nickel plated |
| NPT Slotted Plug – Standard | Flat head, single slot, tapered NPT thread | 1/8″, 1/4″, 3/8″, 1/2″, 3/4″, 1″, 1-1/4″, 1-1/2″, 2″ | Nickel plated |
| Metric Plug with Sealing Washer | As above + EPDM sealing washer (IP54 at entry) | M16–M63 | Nickel plated |
| PG Plug with Sealing Washer | As above + EPDM sealing washer (IP54 at entry) | PG7–PG48 | Nickel plated |
| Metric Plug – Unplated Brass | Bare machined brass, no plating | M16–M63 | Natural brass |
| Mixed-Size Kit Box | Assorted sizes in display box for panel builders | Custom mix per customer specification | Nickel plated |
| Custom Thread / Special Length | Non-standard thread or extended thread engagement | On request (ATEX, Ex d long thread versions) | As specified |
Applications by Industry
| Industry / Application | Typical Use of Brass Conduit Plugs |
|---|---|
| Electrical Panel Building | Sealing unused gland plate knockouts in DB, MCC, PCC, switchgear panels during construction and commissioning |
| EPC Contractors | Blanking unused conduit entries in junction boxes, pull boxes, and cable tray enclosures on project sites |
| Power Utilities | Sealing unused entries in substation control panels, relay panels, and protection panels |
| Oil & Gas (Onshore/Offshore) | NPT metallic plugs for unused entries in ATEX Ex d junction boxes, instrument enclosures, and hazardous area panels |
| Marine / Shipbuilding | Nickel plated brass plugs for unused cable entries in ship’s switchboards, navigation equipment panels, and marine junction boxes |
| Industrial Machinery OEM | Sealing unused motor terminal box entries, control cabinet knockouts, and pendant station unused entries |
| HVAC / Refrigeration | Blanking unused conduit entries in compressor control panels, VFD enclosures, and BMS panels |
| Automation / Control Systems | Sealing unused DIN rail enclosure entries, fieldbus junction box knockouts, and instrument housing entries |
| Renewable Energy | Unused entries in solar inverter enclosures, wind turbine junction boxes, and battery energy storage system (BESS) cabinets |
| Telecommunications | Blanking unused outdoor cabinet entries, fibre distribution enclosure knockouts, and telecom pole-mounted junction boxes |
Manufacturing Process
Step 1 – Raw Material: CW614N / CuZn39Pb3 free-machining brass bar (EN 12164, OES chemical verification, EN 10204 2.2 mill certificate) in diameters from 12 mm to 80 mm depending on plug size. Incoming bar is straightness-checked and burr-inspected before loading into bar feeders.
Step 2 – CNC Automatic Screw Machine Turning: Plug bodies are turned on multi-spindle or CNC Swiss-type automatic screw machines from bar stock in a single setup. Operations performed in-cycle include: face turning and chamfering of head face; thread OD turning; thread cutting or thread rolling (metric); slot milling (live tool or secondary slot mill); and parting/cut-off. Cycle times of 3–8 seconds per plug for M16–M25 sizes, up to 15–25 seconds for M50–M63 sizes.
Step 3 – Thread Production: Metric threads are produced by thread-rolling (on smaller sizes, <M32) or single-point thread turning/chasing (on larger sizes). PG round threads are cut using a specially profiled tool to DIN 40430 geometry. NPT taper threads are cut with NPT taper threading tools and verified with NPT ring gauges (L1 gauge per ASME B1.20.1). Thread-rolled plugs have superior surface finish (Ra <0.8 µm on flanks) and work-hardened thread flanks for improved strip-out resistance.
Step 4 – Slot Milling: The screwdriver slot is milled across the head face using an end mill or slitting saw in a dedicated milling operation or on a live-tool CNC lathe in the same setup as turning. Slot width, depth, and position (centred on head face) are controlled by CNC programme parameters. Slot edges are lightly deburred to prevent plating bridging.
Step 5 – Vibratory Deburring and Cleaning: All machined plugs are vibratory deburred in a ceramic media tumbler to remove sharp edge burrs and turning witness marks, then ultrasonically cleaned in alkaline degreaser to remove cutting oil, metal fines, and polishing compound before plating.
Step 6 – Nickel Plating: Barrel-plated in electroplating line: alkaline degrease → acid activation → copper strike (2–5 µm) → bright nickel plate (5–12 µm, Watts bath) → water rinse → hot-air dry. Plating thickness checked by XRF on sample. Adhesion tested by bend test (ASTM B571).
Step 7 – Inspection and Packing: 100% visual inspection for plating defects, slot damage, and burrs. Thread gauging by GO/NO-GO ring gauge at AQL 1.0 per ISO 2859-1. Dimensional check on head diameter and overall length by calliper. Packed in polybags by size with quantity label, lot number, and part number; or in mixed kit boxes per customer specification.
Quality Standards and Certifications
| Standard / Certification | Applicability to Conduit Plugs |
|---|---|
| ISO 9001:2015 | Quality Management System – manufacture and inspection |
| EN 12164 (CW614N) | Brass bar and rod – raw material specification |
| ASTM B689 / EN ISO 4526 | Electroplated nickel coatings specification |
| ASTM B117 | Salt spray (fog) corrosion testing – nickel plating verification |
| ASTM B571 | Plating adhesion test methods |
| IEC 60423 | Conduit systems – metric thread specification |
| EN 50262 | Metric cable entry devices – thread and dimensions |
| DIN 40430 | PG (Panzergewinde) thread specification |
| ASME B1.20.1 | NPT thread specification and gauging |
| IEC 60529 | IP (Ingress Protection) rating reference |
| IEC 60079-1 | ATEX Ex d thread engagement requirements (reference for hazardous area use) |
| ISO 2859-1 | AQL sampling inspection plan – production inspection |
| EN 10204 2.2 | Test report – material certificates for brass base |
Why Choose Electrical Accessories India for Brass Conduit Plugs
- Full thread range from one source: Metric, PG, and NPT slotted plugs in matching nickel plated brass – consistent finish and quality across all three standards from a single supplier.
- 100% thread gauged: Every production lot GO/NO-GO ring gauge inspected at AQL 1.0 – no field installation failures due to thread form errors.
- Nickel plating quality: Copper-strike process for adhesion + XRF thickness verification + ASTM B117 salt spray testing on each batch.
- CNC automatic screw machine production: Consistent slot geometry, thread form, and head dimensions across millions of pieces per year.
- Competitive ex-India pricing: US$ 11.50/kg – cost-effective supply leveraging Indian manufacturing economics with internationally certified quality.
- Mixed-kit packaging: Custom size mix boxes for panel builder distributors requiring a range of sizes in a single package.
- Export documentation: EN 10204 2.2 material certificate, RoHS/REACH declaration, CoO, and nickel plating test certificate supplied as standard.
- Compatible conduit fitting range: Direct compatibility with Electrical Accessories India conduit bushes, lock nuts, thread adapters, and flexible conduit fittings for a unified single-source supply.
Frequently Asked Questions (FAQ)
1. What is a brass slotted conduit plug and where is it used?
A brass slotted conduit plug is a solid or thin-walled threaded component with a flat head bearing a milled screwdriver slot, used to seal unused conduit entry holes, cable gland knockouts, and tapped apertures in electrical enclosures, junction boxes, motor terminal boxes, and distribution panels. It prevents dust ingress, accidental contact with live parts, and maintains the mechanical integrity of the enclosure at unused entries.
2. What is the difference between Metric, PG, and NPT conduit plugs?
The three types differ in thread form: Metric plugs use ISO metric thread (M16×1.5 to M63×1.5) per IEC 60423 — the current international standard for conduit entries. PG plugs use the German DIN 40430 round thread (PG7 to PG48) — the older European standard widely used in legacy and German-origin installations. NPT plugs use the American tapered pipe thread (1/8″ to 2″) per ASME B1.20.1 — the standard for North American and oil-and-gas project work. Always match the plug thread to the enclosure entry thread — they are not interchangeable.
3. Why specify nickel plated brass plugs instead of unplated brass or zinc die-cast?
Nickel plated brass plugs offer: (1) superior corrosion resistance vs. unplated brass, especially in humid, coastal, and industrial atmospheres; (2) bright uniform appearance matching nickel plated cable glands and lock nuts; (3) better contact resistance for EMC earthing continuity vs. zinc die-cast; (4) higher mechanical strength and thread strip-out resistance vs. zinc die-cast (brass tensile strength 380–430 MPa vs. zinc die-cast ~250 MPa); (5) compliance with RoHS and REACH without cadmium or chromate treatments.
4. Are these plugs suitable for use in ATEX Zone 1 explosion-proof enclosures?
Brass nickel plated metallic plugs (as opposed to plastic bungs) are required for unused entries in ATEX Ex d (flameproof) enclosures per IEC 60079-1. The plug thread engagement must meet the minimum full-thread engagement (typically 5 full threads minimum) per the enclosure manufacturer’s ATEX certificate. Confirm thread engagement length against the certificate requirement before installation. Extended-thread-engagement versions are available on request.
5. What IP rating do the plugs provide when installed?
A metal-to-metal installed plug without sealing provides IP20 minimum (protection against solid objects >12 mm). With a EPDM sealing washer under the plug head, IP54 is achievable at the plug entry. For IP65/IP66, a sealing O-ring in a countersunk groove or thread sealant (PTFE tape on NPT taper thread) is required. The overall enclosure IP rating depends on all entries being properly sealed and the enclosure body/door seals.
6. What is the installation torque for conduit plugs?
Recommended installation torques for nickel plated brass slotted plugs range from approximately 2–3 N·m for M16/PG7 plugs up to 8–12 N·m for M63/PG48 plugs. For NPT taper thread plugs, 2–3 turns past hand-tight with PTFE thread tape is the standard practice per ASME B1.20.1. Excessive torque risks stripping the slot or the enclosure thread; a standard flat screwdriver or torque screwdriver should be used rather than power tools.
7. Are conduit plugs RoHS and REACH compliant?
Yes. The base material (CW614N brass) contains lead at 2.5–3.7%, which is permitted under EU RoHS Directive 2011/65/EU Annex IV Exemption 6(c) for lead in copper alloys for machining. The nickel plating does not contain cadmium, hexavalent chromium, or other RoHS restricted substances. REACH SVHC declarations confirming lead content and absence of SVHC above threshold are supplied with all shipments.
8. Can plugs be supplied with EPDM or silicone sealing washers as a kit?
Yes. Sealing washers in EPDM (temperature range –40°C to +120°C, oil-resistant, UV-stable) or silicone (–60°C to +200°C, high-temperature applications) are available as optional accessories. Kits comprising plug + sealing washer in polybag are available for metric and PG sizes. Silicone sealing washers are recommended for high-temperature environments (near motors, engine rooms, furnace areas).
9. What is the MOQ and lead time for brass conduit plugs?
Standard MOQ is 50 kg per size. For mixed-size orders, total order weight of 50 kg with minimum 5 kg per size is standard. Lead time for standard sizes in stock is 1–2 weeks. Non-standard sizes (extended thread engagement, special head geometry) have 4–6 week lead times. Annual blanket orders with monthly call-off are supported for distributor accounts.
10. Do the plugs come with a material certificate?
Yes. Standard documentation includes EN 10204 Type 2.2 test report confirming CW614N / CuZn39Pb3 brass composition, nickel plating thickness test certificate (XRF), RoHS/REACH declaration, and certificate of origin. EN 10204 Type 3.1 mill certificates from the bar supplier are available on request for critical applications such as ATEX installations or utility project requirements.
Equivalent Terms in Major Languages
| Language | Term 1 | Term 2 | Term 3 | Term 4 |
|---|---|---|---|---|
| Spanish | Tapón de latón para conducto ranurado | Tapón ciego de latón niquelado métrico | Conector de conducto tapón PG latón | Tapón roscado NPT latón niquelado |
| Russian | Латунная заглушка для кабельного ввода | Заглушка с прорезью никелированная латунь | Кабельная заглушка PG с шлицем | Латунная резьбовая заглушка NPT |
| French | Bouchon laiton nickelé pour conduit | Bouchon fendu en laiton fileté métrique | Bouchon PG laiton pour presse-étoupe | Bouchon fileté NPT en laiton nickelé |
| Portuguese | Tampão de latão niquelado para conduite | Bucha cega ranhurada latão métrico | Tampão PG latão para entrada de cabos | Bucha rosca NPT latão niquelado |
| Italian | Tappo in ottone nichelato per condotto | Tappo filettato con intaglio ottone metrico | Tappo PG ottone per pressacavi | Tappo filettato NPT ottone nichelato |
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Request a Quote – Brass Nickel Plated Conduit Plugs (Slotted)
Electrical Accessories India manufactures nickel plated brass slotted conduit plugs in Metric (M16–M63), PG (PG7–PG48), and NPT (1/8″–2″) thread standards for electrical panel builders, EPC contractors, power utilities, distributors, and export customers worldwide. Indicative pricing: US$ 11.50/kilogram. Contact our technical sales team with your size list and quantities for a formal quotation within 24 hours.
📧 Email: info@elecaccs.com | 🌐 Website: www.elecaccs.com