A cable gland is only as reliable as the small parts stacked behind it. The locknut that holds the gland in place, the earth tag that bonds the armour to ground, the sealing washer that keeps water out, and the blanking plug that closes an unused hole all decide whether the finished installation actually meets its IP rating and its electrical safety requirements. Treat any of them as an afterthought and the gland will leak, lose continuity or vibrate loose long before the cable itself gives up.

This guide walks through the complete list of cable gland accessories you are likely to meet on a real build — locknuts, earth tags, sealing washers, reducers and enlargers, blanking plugs and breathable vent plugs — and explains which ones you actually need for metal enclosures, non-metallic enclosures, painted panels and threaded holes that do not quite line up.

What Counts as a Cable Gland Accessory?

A cable gland accessory is any component that is not part of the gland body itself but is fitted in the same stack to make the gland work. The minimum stack on a non-threaded enclosure is a sealing washer, the gland, and a locknut. Add an earth tag and a PVC shroud when the armour or braid has to be earthed, and add a reducer or enlarger when the thread on the gland does not match the hole in the panel. A blanking plug, a screw plug, or a breathable vent plug handles the entries that have no cable going through them at all.

For most installations, six accessory families cover everything you will meet on a cable gland accessories list:

• Standard and EMC locknuts for fixing the gland to the enclosure
• Earth tags, earthing nuts and PVC shrouds for bonding metallic sheaths to ground
• Sealing washers and O-rings for keeping the enclosure at IP54, IP66, IP67 or IP68
• Reducers and enlargers for converting between Metric, PG, G and NPT threads
• Blanking plugs, screw plugs and plastic clips for sealing unused entries
• Breathable vent plugs for pressure equalisation in sealed enclosures

Complete List of Cable Gland Accessories

The table below is the short version. Each accessory is then covered in its own section with the real thread range, materials and fit-up notes drawn from the Jixiang Connector accessory range.

Locknuts: Standard and EMC

Locknuts are the most common cable gland accessory. A locknut is a hex or round nut threaded onto the back of the gland once it has been pushed through the panel. Tightening the locknut pulls the gland shoulder against the enclosure face and stops the gland from rotating or vibrating loose.

Standard locknut

A standard locknut is purely mechanical. It clamps the gland to the panel and is made in nickel-plated brass, stainless steel 304 and stainless steel 316L to match the gland itself. Thread ranges typically cover Metric M12 to M100, PG7 to PG48, plus G and NPT, so the same locknut family works across most industrial panels.

The relevant product is the Standard Locknut from Jixiang Connector, available in nickel-plated brass, SS304 and SS316L with the full Metric, PG, G and NPT thread range. Torque the locknut to the gland manufacturer’s published value — typically 10 to 15 Nm for an M20 brass gland — using a calibrated wrench in two passes (snug, then final). The companion guide cable gland torque specifications and sealing points covers the full torque table for nylon, brass and stainless glands.

EMC locknut

An EMC locknut does the same job as a standard locknut but with sharpened teeth or a star washer on the mating face. Those teeth bite through paint, anodising and oxide to give a low-resistance path between the gland body and the enclosure. Use an EMC locknut with EMC glands, shielded cables, inverter panels and any installation that has to meet a conducted-emissions target.

The matching EMC Locknut is offered in the same three materials and the same M12 to M100 / PG7 to PG48 thread range.

Earth Tags: When Earthing Is Not Optional

An earth tag (also called a banjo washer, earthing washer or earthing nut) is a flat brass washer with a tag or tail that is clamped between the gland body and the enclosure. A green/yellow earth conductor is then crimped or screwed onto the tag and run back to the enclosure earth bar. The tag gives the cable armour, braid or metallic sheath a defined path to ground.

Metal enclosures, plastic enclosures and the painted panel trap

The IEC 60364 rule is simple: anything metallic that could become live under a fault has to be earthed. That includes the steel wire armour (SWA) on an armoured cable and the copper braid on a braided cable. Three cases decide whether an earth tag is mandatory:

• Non-metallic enclosure (plastic, GRP, stainless painted, fibreglass). The gland body has no conductive path back to ground. Without an earth tag, the armour or braid floats at an undefined potential and a touch can be fatal under fault conditions.
• Painted, powder-coated or epoxy-coated metal enclosure. The brass gland sitting on a coated steel panel is electrically isolated by the coating. A small resistance at the interface can defeat the protection. The fix is the earth tag.
• Bare galvanised or stainless steel enclosure with clean metal-to-metal contact. The gland body bonds to the panel through the threads, so an earth tag is optional — but many specifiers still call for one as belt and braces.

Fitting an earth tag with a PVC shroud

The earth tag is slid over the gland thread before the locknut and is clamped between the gland shoulder and the enclosure face when the locknut is tightened. A PVC shroud is then fitted over the assembly to insulate the brass, protect it from dirt and give the installation a tidy finish. The Earth Tag with PVC Shroud from Jixiang Connector covers Metric M20 to M100, G and NPT threads.

Sealing Washers and O-Rings: Protecting the IP Rating

A sealing washer (sometimes called an entry thread seal) sits under the gland shoulder and gaskets the gland to the enclosure face. Without it, the joint between the brass gland and the painted panel is the weak point in the IP chain, even when the gland itself is rated IP68.

Tapped holes versus untapped clearance holes

The need for a sealing washer depends on the entry hole, not the gland:

• Tapped (threaded) hole. The gland threads into the panel. A light cut of sealing compound or an O-ring on the thread is usually enough to hold IP54. Many gland kits include a nylon washer that is acceptable for indoor, dry panels.
• Untapped clearance hole. The gland passes through a plain round hole and is fixed only by the locknut on the inside. A sealing washer is mandatory to reach IP55, IP66, IP67, IP68 or IP69K. CMP Products and most industrial gland manufacturers recommend an approved entry thread sealing washer for any installation rated IP55 and above.

Material choice matters: use EPDM or nitrile for general-purpose sealing, fibre washers for high-temperature panels, and PTFE or Viton for chemical exposure. The washer sits under the gland shoulder, not under the locknut, so it is compressed by the gland body — not by the locknut on the inside.

Reducers and Enlargers: Fixing Mismatched Threads

A thread reducer drops a larger tapped hole down to a smaller gland thread. An enlarger does the opposite: it steps a smaller gland up to a larger hole. Both are supplied with a locknut and a sealing washer, and both are made in nickel-plated brass, SS304 or SS316L to match the gland.

Use a reducer or enlarger when:

• The equipment is pre-drilled with a thread that does not match the cable gland you have in stock.
• You are retrofitting an enclosure and the original tapped holes are too large or too small.
• You are converting between Metric, PG, G and NPT on a mixed-spec panel.

The relevant product is the Thread Reducer Adapter, with the matching enlarger in the same range. Ambient temperature is typically −40 °C to +100 °C, with +120 °C allowed for short periods. A common-sense check before ordering: measure the existing tapped hole, write down whether it is Metric, PG or NPT, then pick the reducer or enlarger with the matching threads on both ends.

Blanking Plugs: Closing Unused Entries

Every spare entry on a junction box is a water path waiting to open. A blanking plug closes the hole with the same IP rating as a fully populated gland, so the enclosure rating holds when you add or remove cables later. Two families cover most cases:

• Screw plug (blind plug). Threads into an existing M or PG entry. PA66 nylon with NBR or EPDM O-ring, IP68 with the O-ring fitted, −40 °C to +100 °C static, thread sizes PG7 to PG48 and M12 to M63. The matching product is the Nylon Blind Screw Plug.
• Plastic clip. A push-in plug for plain, untapped knockout holes on plastic or steel enclosures. PA66 nylon with NBR or EPDM O-ring, IP68 with O-ring, M5 to M60 size range, black RAL9005 or grey RAL7035 with custom colours available.

For outdoor or washdown enclosures, fit the O-ring and tighten to the manufacturer’s torque. A blanking plug without its O-ring will leak long before the gland next to it does.

Breathable Vent Plugs: Pressure Equalisation

Sealed enclosures heat up during the day and cool down at night. The air inside expands and contracts, and if the enclosure cannot breathe, the pressure differential pumps moisture in through every cable entry and gasket. The result is condensation on the electronics, especially on LED drivers, solar combiner boxes and outdoor telecom cabinets.

A breathable vent plug solves that without compromising the IP rating. The plug uses a microporous membrane (typically Gore-style expanded PTFE) that lets air pass but blocks liquid water. Typical ratings are waterproof to 3 to 5 metres, O-ring IP68, airflow around 325 ml/min at 0.07 bar, water entry pressure above 5 bar, and operating temperature −40 °C to +120 °C (up to +150 °C short term). The Breathable Vent Plug is available in stainless steel, nickel-plated brass, nylon PA6 and aluminium, with RoHS and CE certification. Use one vent plug per sealed enclosure, next to the cable glands rather than in place of them.

Correct Assembly Order for Cable Gland Accessories

Most field failures trace back to the stack being assembled in the wrong order. The exact sequence depends on whether the gland is fitted from the outside (typical) or from the inside (some cabinets), but the principle is the same: every component must be clamped between the gland shoulder and the enclosure face, not floating around the threads.

1. Prepare the hole. Clean, round, free of burrs and paint at the contact face. For untapped clearance holes, confirm the diameter matches the gland shoulder.
2. Slide the sealing washer onto the gland thread against the gland shoulder. This is the IP-rated face of the stack.
3. Slide the earth tag (if used) over the thread with the tail pointing towards the earth bar inside the enclosure.
4. Pass the gland body through the hole from the outside, so the sealing washer and earth tag land on the outside face of the panel.
5. Fit the locknut on the inside and tighten to the gland manufacturer’s torque. The locknut clamps the stack together.
6. Crimp the earth conductor onto the tag and run it to the enclosure earth bar.
7. Fit the PVC shroud over the gland body for outdoor or washdown installations.
8. Tighten the compression nut on the gland body to its published torque so the seal grips the cable.

The order is what makes the earthing, sealing and mechanical fixing work at the same time. Swap the sealing washer and the earth tag and the gland will still tighten, but the earthing path will not bite through paint and the IP rating drops.

Material Selection and Compatibility

Cable gland accessories are typically offered in three metal families plus nylon. Match the accessory material to the gland material and to the environment, or you risk galvanic corrosion, galling and early failure.

Galvanic corrosion is the silent killer of mixed-metal accessories. A brass locknut on an aluminium enclosure in a wet environment will pit through in months. The rule is simple: same metal family on both sides of the joint, and never couple brass directly to aluminium outdoors.

Common Mistakes When Buying Cable Gland Accessories

How to Order Cable Gland Accessories

A short checklist that stops most reorder errors before they ship:

• Thread standard and size. Write down M, PG, G or NPT and the nominal size on both the gland and the enclosure hole. A 20 mm hole is not the same as an M20 thread.
• Material. Brass, SS304, SS316L or nylon, matched to the gland and the environment.
• IP target. IP54 indoor dry, IP66 outdoor, IP67 temporary immersion, IP68 continuous immersion, IP69K high-pressure washdown. The sealing washer and O-ring choice both depend on this.
• Earthing requirement. Metal-to-metal bite, painted panel, non-metallic enclosure, or armoured cable — each picks a different earth tag and locknut combination.
• Quantity of spare entries. Order blanking plugs and vent plugs at the same time as the glands so the enclosure is sealed on day one.

For custom thread combinations, OEM packaging or non-standard materials, send a sample or drawing to the manufacturer. Jixiang Connector offers OEM and ODM service with low MOQ and two free samples for testing, delivered within three to seven days.

Conclusion

Cable gland accessories are the parts that decide whether the cable gland actually does its job. A standard or EMC locknut holds the gland in place, an earth tag with a PVC shroud bonds the armour or braid to ground, a sealing washer keeps the enclosure at IP54 or higher, a reducer or enlarger fixes mismatched Metric, PG, G or NPT threads, and a screw plug or breathable vent plug closes every spare entry without losing the IP rating. Match the materials, follow the assembly order, and torque each component to the published value — the installation will then keep its IP rating and its electrical safety for the full design life of the equipment.

Browse the full range of cable gland accessories from Jixiang Connector, or contact the engineering team with your panel drawings for a custom accessory pack.

Frequently Asked Questions

What is a cable gland locknut and what does it do?

A cable gland locknut is a hex or round nut threaded onto the back of a cable gland once the gland has been pushed through a panel. It clamps the gland shoulder against the enclosure face so the gland cannot rotate, vibrate loose or pull out. Standard locknuts are purely mechanical; EMC locknuts have a toothed or star face that bites through paint and oxide to maintain shield continuity.

When is a cable gland earth tag required?

An earth tag (also called a banjo washer or earthing nut) is required whenever the cable gland cannot bond directly to a clean, bare-metal enclosure. That includes any non-metallic enclosure (plastic, GRP, fibreglass) and any metal enclosure with a painted, powder-coated, epoxy-coated or anodised entry face. The earth tag gives the cable armour, braid or metallic sheath a defined path back to the enclosure earth bar and satisfies IEC 60364 earthing requirements.

Do I need a sealing washer under every cable gland?

You need a sealing washer whenever the entry hole is an untapped round hole rather than a tapped thread, and on any installation rated IP55 or higher. Tapped holes on a clean metal face can sometimes rely on an O-ring or thread sealant alone, but most industrial specs call for an approved entry thread sealing washer regardless, because it is the cheapest way to guarantee the IP rating on the finished joint.

What is the difference between a cable gland reducer and an enlarger?

A reducer steps a larger tapped hole down to a smaller gland thread (for example M32 down to M20). An enlarger steps a smaller gland thread up to a larger hole (for example M20 up to M32). Both are used when the equipment is pre-drilled with a thread that does not match the gland on the cable. Both are supplied with a locknut and a sealing washer and both are available in Metric, PG and NPT combinations.

Can a screw plug replace a cable gland on an unused entry?

Yes. A blind screw plug is the standard way to seal an unused threaded entry on a junction box or control panel. The screw plug uses the same thread as the cable gland (Metric M12 to M63 or PG7 to PG48), is fitted with an NBR or EPDM O-ring, and reaches IP68 with the O-ring in place. For untapped knockout holes, use a plastic clip of the matching size instead.

Do cable gland accessories come with different thread standards?

Yes. Standard and EMC locknuts typically cover Metric M12 to M100, PG7 to PG48, plus G and NPT. Earth tags cover Metric M20 to M100 with G and NPT. Reducers and enlargers cover Metric, PG and NPT combinations. Screw plugs cover PG7 to PG48 and M12 to M63. Always confirm the thread standard on both the gland and the enclosure hole before ordering, and write the standard (Metric / PG / G / NPT) and the nominal size on the purchase order so there is no confusion on the shop floor.