Metal contact alone does not prove that a cable gland has an acceptable protective bonding path. The mounting can provide that path when its documented construction, installation and verification support it. Otherwise, use the gland’s approved bonding provision, such as an earth tag and correctly sized conductor. A sealing washer does not automatically require a jumper, but neither does a tight locknut prove continuity. For hazardous locations, follow the certified assembly’s instructions rather than applying ordinary junction-box assumptions.
What a bonded gland must achieve
Protective bonding connects metal parts into a dependable path that can carry fault current until the protective device operates. The path must remain effective through normal vibration, maintenance and environmental exposure.
For a metallic cable gland in a stainless junction box, identify every interface between the gland and the protective earth terminal. Depending on the construction, that path may include:
- The gland body and its entry threads.
- A threaded enclosure wall, locknut or approved bonding accessory.
- A removable gland plate and its connection to the enclosure.
- The enclosure body and its protective earth connection.
- The equipment grounding conductor returning toward the supply.
One sound connection does not compensate for another unreliable interface. A gland can be electrically connected to a plate while the plate remains inadequately bonded to the box.
In US installations, NEC 250.96(A) addresses bonding metal parts intended to serve as equipment grounding conductors. NEC 250.4(A)(5) describes the effective ground-fault current path; the earth is not part of that path. A nearby ground rod therefore does not replace the equipment grounding conductor.
Use the enclosure grounding and bonding guide for the overall protective-earth arrangement. The gland-specific question is whether the installed mounting provides the required connection within that arrangement.
What ratings and continuity tests establish
Ingress protection and protective bonding answer different questions. A water-resistant entry can have an unsuitable electrical connection. A conductive entry can still leak.
An IP code under IEC 60529 describes protection against access, solid objects and water under specified tests. It does not, by itself, establish gland-to-box fault-current capability or suitability for a hazardous location.
Likewise, a gland’s component documentation applies within its stated installation conditions. Those conditions may specify the entry construction, accessories, thread engagement, torque and cable type. A rating printed on a loose component does not validate every possible mounting arrangement.
Our catalog wall-mount enclosures are rated NEMA 4X / IP66 by the manufacturer; not UL listed. That enclosure rating does not establish the bonding performance of a field-installed gland or guarantee the rating after modification.
A continuity measurement establishes something narrower: an electrical path exists under the conditions of the test. It does not independently prove that the connection can carry the prospective fault current. Nor does it prove that the connection will remain sound after corrosion, loosening or maintenance.
A handheld meter’s continuity beep is especially limited. Its threshold may accept more resistance than the project permits, and parallel conductors can conceal a defective mounting interface. Acceptance must combine suitable construction, documented installation and the required verification method.
When the mounting needs a separate bond
A separate wire between every gland is not a universal requirement. The decision depends on the approved connection arrangement and the installation rules that apply.
| Mounting arrangement | What you must establish | When a separate bond is needed |
|---|---|---|
| Metal gland in a threaded stainless entry | Correct thread form, adequate engagement and a documented protective bonding path | When the mounting is not accepted for bonding, or the instructions require a separate connection |
| Metal gland through a clearance hole with a locknut | An accepted gland, locknut and wall arrangement with reliable electrical contact | When the ordinary locknut arrangement does not establish the required path |
| Gland installed with a sealing washer | A valid electrical path through threads or other approved contact surfaces | When insulating components interrupt that path or the documented arrangement requires an earth tag |
| Gland on a removable metal plate | Continuity across both gland-to-plate and plate-to-enclosure interfaces | When plate fasteners or other mounting details do not provide an accepted bond |
| Gland mounted through an insulating insert | A dedicated protective bonding provision independent of the insert | When the gland requires bonding and no other accepted path exists |
A face-sealing washer normally sits between particular mounting surfaces. It may leave an accepted threaded path intact, or it may be part of an arrangement that needs a bonding accessory. Review the assembly cross-section rather than judging only the visible washer.
Do not remove a sealing washer to obtain metal contact. Do not add a serrated washer in an arbitrary location and assume both sealing and bonding remain valid. Use the accessory stack and tightening instructions specified for the gland and enclosure arrangement.
Thread engagement also matters. A sealing washer, earth tag and thick enclosure wall can leave insufficient thread for the locknut. The article on a cable gland too short for junction box threads explains that dimensional problem.
Thread adapters introduce further interfaces. For mixed entries, check G thread versus NPT cable gland adapters before selecting the sealing and bonding arrangement. Thread sealant must be permitted by the component instructions; it is not evidence of electrical continuity.
Armour and shields have different jobs
Cable armour, a metallic gland body and a cable shield can all require connections, but their purposes differ.
An armour gland must suit the actual armour construction and cable dimensions. Its armour termination provides mechanical retention and, where specified, an electrical connection. A gland that seals an outer jacket does not necessarily terminate the armour beneath it.
If armour is intended to serve as a protective conductor, confirm that the applicable wiring rules permit that use. Its electrical capacity, continuity and terminations must satisfy the installation design. Do not assume that all armour can replace a separate protective conductor.
An earth tag provides a connection point for bonding the gland assembly. It does not automatically correct an unsuitable armour clamp or an incorrectly assembled gland. The complete path must remain valid from the armour through its termination and onward to protective earth.
Cable shields primarily control interference. Their termination depends on the equipment’s electromagnetic compatibility requirements and the system’s grounding design. A drain wire is not automatically a protective conductor, and an EMC gland is not automatically an armour termination.
Do not disconnect a required protective bond to address signal noise. Resolve shield termination and protective bonding as coordinated but separate design questions. Any functional earth arrangement must preserve the required safety connections.
For an unarmoured cable, the metallic gland may still require bonding if it can become energized under a fault. The absence of armour does not settle the gland-body question.
Verify the complete assembled connection
Inspection starts with the documented arrangement, not with a meter. Before opening or altering electrical equipment, isolate all sources, apply the required lockout procedure and verify absence of voltage. Use personnel qualified for the installation and its verification requirements.
Check the following details against the component instructions and approved drawing:
- Gland model, cable construction and permitted cable diameter range.
- Entry thread type, wall thickness and available thread engagement.
- Locknut, sealing washer, earth tag and adapter compatibility.
- Clean, sound bonding contact surfaces and specified tightening torque.
- Protective conductor termination, conductor sizing and mechanical protection.
- Gland plate bonding, where a removable plate is fitted.
- Corrosion, damaged threads, loose hardware or evidence of cable movement.
Stainless steel construction does not eliminate the need to inspect contact surfaces. Paint, adhesive films, contamination and insulating accessories can interrupt an intended connection. NEC 250.12 addresses nonconductive coatings at grounding and bonding contact surfaces. It is not permission to modify a sealing land or a certified component contrary to its instructions.
Where an earth tag is required, use a compatible accessory and terminal arrangement. Size its conductor using the applicable protective bonding rules and fault conditions, not simply whatever wire fits the tag. Do not rely on an arbitrary loop between glands as proof that each gland is properly bonded.
Verify continuity using the instrument, test current and acceptance criteria required by the applicable standard or project procedure. There is no universal resistance limit suitable for every gland assembly. Record the measurement points and results so later inspections can identify changes.
Parallel armour, shields or bonding conductors can mask a poor mechanical interface. Any isolation needed to distinguish paths must follow an approved test procedure. Restore and verify every disturbed connection before returning equipment to service.
Finally, check the seal separately. Confirm correct gasket seating, cable sealing and unused-entry closure. Electrical continuity cannot demonstrate water resistance.
What to specify for the enclosure
Put the bonding arrangement on the entry drawing rather than leaving it to installation judgment. For each gland, specify the cable construction, cable diameter, entry type, mounting thickness and required accessories.
Show whether the accepted protective path uses the gland mounting or a separate bonding conductor. Identify the enclosure earth terminal and any gland plate bond. Include conductor sizing requirements, terminal details, tightening instructions and the verification procedure.
For removable entry panels, when to specify a stainless enclosure with a gland plate covers the additional mechanical and sealing interfaces. The plate’s bonding arrangement belongs on the same approval drawing.
Use custom stainless enclosures and factory cutouts when the body or entry pattern needs modification. Review component clearances, sealing surfaces and bonding access before approving the drawing. Factory-made openings do not automatically preserve the assembled rating.
The stainless enclosure size finder helps select a body with room for glands, internal terminals and conductor bends. Leave enough internal access to tighten locknuts, inspect earth tags and test connections without disturbing adjacent entries.
For hazardous locations, identify the area classification and required protection concept before selecting the enclosure and glands. Follow the certified assembly’s instructions and applicable installation requirements, including the relevant IEC 60079 standards where applicable. Do not add accessories, modify entries or assume ordinary metal contact satisfies those requirements.
We do not build hazardous-location enclosures. An ordinary stainless enclosure with a water-ingress rating is not a substitute for the certified assembly required by that location.
Enclosures for this job
Catalog sizes that suit the job this article answers, picked from its subject; open one for its full specifications.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 6 × 6 × 4 in | 304 stainless | 6 x 6 x 4 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 8 × 6 × 4 in | 304 stainless | 8 x 6 x 4 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 10 × 8 × 4 in | 304 stainless | 10 x 8 x 4 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does every metal cable gland need a separate bonding wire?
No. A separate conductor is not universally required when the documented mounting arrangement provides an accepted protective bonding path. Use a separate connection when the component instructions, installation rules or assembly design require it, or when the mounting cannot establish that path. Verify the complete arrangement rather than relying on visible metal contact.
Does a sealing washer electrically isolate a cable gland?
Not necessarily. A face-sealing washer may leave an accepted conductive path through the entry threads or other specified contact surfaces. Other arrangements introduce electrical isolation. Follow the documented accessory arrangement, and never remove a required seal merely to obtain metal contact.
Can cable armour serve as the protective conductor?
Only where the applicable wiring rules permit it and the installation design establishes adequate electrical capacity, continuity and terminations. The gland must correctly terminate the actual armour construction. Neither the presence of armour nor a metallic gland alone proves that a separate protective conductor is unnecessary.
Is a continuity beep enough to accept the gland bond?
No. A continuity beep only indicates a path within the meter’s threshold, and parallel connections can hide a defective interface. Verification must also establish suitable construction and correct installation. Use the test method and acceptance criteria required by the applicable standard or project procedure.
Can the same bonding assumptions be used in a hazardous location?
No. Hazardous-location installations require the enclosure, glands and accessories specified for the applicable protection concept and certified assembly. Follow those instructions and local installation requirements. Ordinary metal contact or a water-ingress rating does not establish hazardous-location suitability, and we do not build hazardous-location enclosures.
