Specify evidence—not a target Newton number
The result is meaningful only for the exact terminal, conductor, test method and stated outcome.
Terminal engineering qualification guide
Terminal Block Pull-Out Force and Conductor Retention
Terminal block pull-out force is condition-bound laboratory evidence for a defined terminal, conductor, method and pass criterion—not an allowable cable-load rating. A credible release matches the exact connection and separately controls every mechanical force path in the finished assembly.
Not a working loadA laboratory force or result does not authorize continuous cable tension.
Match every conditionPart number, conductor, preparation, method, duration and pass criterion all matter.
Six force pathsClamp, flexion, rail, plug, strain relief and fault bracing need separate evidence.
No improvised tug testUse only an exact OEM or released quality procedure under safe deenergized controls.
Field installation context only; the photo does not prove terminal pull-out force, conductor retention or compliance. Photo: MTA Capital Construction Mega Projects / Wikimedia Commons, CC BY 2.0. Center-cropped, scaled and darkened in CSS for layout; no technical marking was intentionally altered.
Freeze the exact configuration
Record full part number, revision, pole level, accessories, rail/support, plug and connection point.
Describe the actual wire
Material, cross-section, solid/flexible/stranded construction, count and approved ferrule condition change the evidence.
Preserve the test context
Standard edition, sequence, force, duration, direction and pass criterion must travel with the number.
Critical interpretation boundary: a terminal pull-out value does not prove cable strain relief, repeated-motion endurance, vibration life, plug latching, DIN-rail attachment, PCB retention or conductor bracing during a short circuit. If the real service applies any of those loads, design and verify that interface separately.
Start with the exact terminal block product range, then use the terminal block selection guide to identify the full order code and application before requesting retention evidence.
One assembly, six different questions
Panel-builder application supportDo not collapse every mechanical load into pull-out force
A project can require evidence in several rows at once. Each interface has its own specimen, method and system owner.
Axial pull-out retention
Evaluates a specified conductor retained in a specified clamping point under a defined tensile test.
Does not prove rail attachment or external strain relief.Bending or movement sequence
Evaluates response to prescribed conductor movement. A pull-out test may follow a defined flexion test, but the questions remain distinct.
Does not create unlimited motion or vibration life.Block-to-rail attachment
Evaluates whether the terminal body remains fixed to the declared DIN rail/support with the required end stops or accessories.
Does not prove the wire stays in the clamp.Plug-to-base retention
Evaluates latch, lock, mating cycles and environmental behavior at a removable plug or connector interface.
Does not prove wire-to-plug retention.Entry and strain relief
Diverts cable weight, handling, side load and service movement away from the electrical contact.
A terminal clamp is not a cable gland or harness support.Short-circuit force restraint
Addresses equipment-level electrodynamic forces through conductor routing, bracing and marked assembly instructions.
Ordinary pull-out data does not prove fault bracing.Assembly boundary: UL guidance for switchboards shows that conductor bracing under fault conditions can require equipment marking and instructions. That is a system fault-duty decision—not a conclusion created by an ordinary terminal-block pull-out result.
How to read the number
01 / TEST FORCE
02 / SETPOINT
03 / MINIMUM RESULT
04 / REMOVAL FORCE
Four labels that must not be treated as synonyms
A catalog field can show a prescribed test level, a laboratory setpoint, a minimum result or the force at removal. Preserve the source wording before comparing products.
Prescribed load
A standard or procedure can specify the tensile force applied to the defined specimen for a stated duration and direction.
Not a continuous service allowance.Laboratory target
The test machine can be set to a required force. Passing that setpoint does not tell you the exact ultimate removal force.
Keep method and tolerance attached.A value such as >80 N
The greater-than sign reports performance beyond the shown threshold under the cited product/test conditions.
Do not replace it with 80 N working load.Force at disengagement
Some procedures may record the load at which the conductor leaves the clamp. It cannot be compared blindly with a pass/fail setpoint.
Compare only equivalent methods.
A test condition is not a field instruction
Record the complete specimen, sequence and pass criterion
A useful engineering statement is specific: “This exact terminal-and-conductor combination has published retention evidence under these named conditions.” A weak statement says only: “This terminal is rated for a 90 N pull.” The weak version hides whether 90 N is a setpoint or observed outcome, which conductor was used, what preceded the test and what counted as a pass.
A pull-out test may be performed directly after a defined flexion test, while aging, reconnection, vibration and other evaluations are separate unless the cited report explicitly combines them. Record the exact sequence instead of assuming that every test belongs to one continuous procedure.
Weidmüller describes a terminal-block method in which a cross-section-dependent force is applied for 60 seconds after flexion and the conductor must neither move out of the connection point nor break near it. WAGO publishes pull-out, vibration, shock and voltage-drop-under-bending as separate laboratory topics. These sources demonstrate why test identity matters; they do not create a universal field procedure.
No generic tug test: do not turn a catalog number or type-test requirement into an improvised incoming, production or field pull. Use a retention check only when the exact OEM instruction or released engineering/quality plan defines the specimen, safe deenergized condition, tool, force, direction, duration and acceptance rule.
To locate the controlling fields, read the exact terminal specifications and interpret the terminal markings and evidence before comparison.
Standards are different layers
Compare terminal certification routesUse the right scope—and the locally controlled edition
As of 20 August 2026, the following public records define the key boundaries. Detailed test clauses remain in the controlled standards and certification records.
IEC 60947-7-1:2025
Industrial screw-type and screwless terminal blocks in its scope, fixed to a support for copper conductors. It is a product-standard framework—not a universal cable-load table.
Official IEC recordIEC TS 60947-7-5:2021
Separate technical-specification route for terminal blocks for aluminum conductors. Exact product material approval and instructions still govern.
Official IEC recordIEC 60999-1:1999
Safety context for screw-type and screwless clamping units for copper conductors. A cited model can use this method without becoming interchangeable with a rail terminal.
Official IEC recordUL 1059, Sixth Edition
Terminal-block component requirements. UL explicitly notes that compliance alone does not assure suitability in every end product; actual service can need added evaluation.
Official UL recordMaterial and market boundary: copper evidence must not be transferred to aluminum. Use an exact AL/AL-CU terminal and its current written method; the separate guide on aluminum wire in terminal blocks explains that qualification gate. Likewise, do not convert IEC test data into a UL end-product conclusion—or the reverse—without the responsible conformity review. The current overview of IEC 60947-7-1:2025 terminal requirements provides additional scope context.
OEM product data checked 20 August 2026
Illustrative published entries—not allowable loads
The entries demonstrate documentation structure. Every >N value remains model-, conductor- and cited-test-specific; it is not a removal force, field target, continuous load or brand-wide rating.
| Exact OEM example | Published conductor/test entries | Source context | Do not infer |
|---|---|---|---|
| Phoenix Contact UWV 4 / 3073380 | 0.25 mm² solid: >10 N; 0.25 mm² flexible: >10 N; 6 mm² solid: >80 N; 4 mm² flexible: >60 N. | Manufacturer field “tractive force setpoint/actual value”; product page cites IEC 60947-7-1:2009-04. | A value for every 4 or 6 mm² terminal, every conductor construction, a service load or compliance to a newer edition. |
| Phoenix Contact HDFK 25 / 0707743 | 6 mm² solid: >80 N; 10 mm² flexible: >90 N; 25 mm² flexible: >135 N; 35 mm² stranded: >190 N. | Same combined manufacturer field; product page cites IEC 60947-7-1:2009-04. | A linear force formula, a working load, approval of another suffix or a general “high-current terminal” result. |
| Phoenix Contact PTSA 1.5 / 1434822 | 0.2 mm² solid/flexible: >10 N; 1.5 mm² solid/flexible: >40 N. | PCB terminal data citing IEC 60999-1:1999-11. | DIN-rail attachment, PCB/header retention, enclosure strain relief or a rail-terminal result. |
The current IEC 60947-7-1 edition is 2025, while the first two OEM pages cite the 2009 edition. Preserve that source context and confirm the product's current certification, document revision and target-market acceptance before engineering release.
Connection technology changes the evidence
No clamp style is universally strongest
A screw/tension-sleeve terminal, screwless spring terminal, push-in terminal, bolted/lug connection, pluggable terminal and PCB terminal each combine different conductor conditions, contact geometry, mounting interfaces and process controls. The safe question is not “Which style has the best pull-out force?” It is “Which exact product has evidence for our wire, environment, assembly and force paths?”
For screw connections, the terminal's exact conductor range, approved conductor count, hardware and manufacturer-specified terminal torque define the evaluated system. More torque cannot repair a mismatched wire or replace retention evidence.
For spring and push-in systems, the declared conductor construction, actuation method and permitted ferrule condition define the system. Review the exact spring terminal family rather than importing a result from another clamp. The same applies to the chosen screw terminal family.
Electrical and mechanical evidence also answer different questions. Current rating versus actual load addresses thermal/electrical suitability; it does not prove that the conductor or terminal support survives the mechanical environment.
Why evidence changes
A terminal does not hold an abstract “wire”
It holds one physical conductor through one prepared interface in one product and assembly configuration.
Series, suffix and revision
Clamp, pole count, housing, rail foot, plug, latch, cover, jumper and production revision can change approved conditions.
Copper or approved aluminum
Material, plating/surface, temperature and exact product identification affect the connection system.
Solid, stranded or flexible
Nominal cross-section alone does not describe strand pattern, class, compaction or mechanical interaction.
One or permitted multiples
Connection capacity does not authorize two conductors unless the exact clamping point declares that arrangement.
Strip, ferrule or lug
Preparation method and approved tooling alter the termination system and must match the tested/documented configuration.
Rail, support and end stops
Terminal-to-support retention belongs to the exact rail/profile, mounting direction and required accessories.
Vibration, shock and temperature
Dynamic and thermal conditions add stresses absent from a room-condition axial pull test.
Routing, entry and service
Cable mass, side load, moving doors, plugs and fault forces can bypass the clamp-test assumptions.
Use the AWG and conductor-size guide for the separate size/construction field, and retain the terminal's exact strip-length requirement as part of the approved preparation record.
Ferrules change the termination system
A ferrule is not an automatic retention upgrade
A ferrule can improve strand containment or process repeatability only when the exact terminal and released assembly process accept that configuration. It is not a universal method for increasing pull-out force, converting an unsupported conductor class or fitting two conductors into a one-conductor connection.
Verify conductor size and construction, single or twin ferrule, bare or insulated sleeve, barrel length, collar geometry, crimp profile, approved tool/die and permitted conductor count. The ferrule manufacturer defines its conductor-preparation/crimp system; the terminal manufacturer defines which finished ferrule geometry is accepted.
The dedicated guide to permitted ferrule conditions explains why the bare-wire and ferruled evidence paths must remain separate.
Do not “fix” a concern by changing preparation: adding a ferrule, tinning, twisting strands, changing the strip length or increasing screw torque without exact authorization creates a new, unreviewed termination system.
Application matrix
Ask for the evidence that matches the real force path
The examples are planning prompts, not prescriptive designs. A component type test can be valid while the finished system still needs separate mechanical controls.
Ordinary clamp retention
Request exact terminal/conductor approval, connection instructions and controlled routing. Reconnection durability may matter where service is expected.
Control substitutions and terminal-plan revisions.Flexion and side load
A door, service loop or frequent access can apply bending that an axial pull test does not reproduce.
Route and support wires so servicing does not load contacts.Vibration and shock
Request product-specific environmental qualification plus the exact rail/support, locks, plugs and harness support.
Match the real vibration profile—not a generic claim.Two retention interfaces
Wire-to-plug retention and plug-to-base latch/cycle behavior are separate. Cable handling adds a third path.
Specify locks, coding and strain relief as a system.Electrodynamic restraint
Use equipment markings/instructions, available-fault-current data and an approved conductor-bracing plan.
Do not cite ordinary pull-out data as fault bracing.Clamp, board and housing
Even when the wire stays clamped, the header, solder joint, board, housing and cable entry can have independent limits.
Keep cable load away from unsupported board interfaces.
Dynamic service conditions
Axial pull-out cannot stand in for vibration evidence
WAGO lists pull-out, vibration, shock and voltage drop under bending as distinct laboratory evaluations. Weidmüller likewise separates flexion/pull-out, block-to-rail attachment, plug cycles and vibration/shock. A single force value cannot be stretched across those tests.
For a vehicle, rotating machine, process skid, rail application, moving panel door or removable I/O assembly, define the vibration/shock profile and ask for exact product evidence. Include the terminal, conductor, rail, end stops, plug locks, harness support, cable route and temperature range that form the installed system.
Accessories can be structurally important. Record the specified rail, end brackets, locks, covers, plugs and strain-relief parts rather than treating them as cosmetic additions. The separate guide to terminal-block accessories helps turn the approved configuration into a complete BOM.
Comparison rule: compare two products only when conductor specimens, force definitions, test sequences, environmental profiles and pass criteria are equivalent. A larger headline number from a different method is not proof of a stronger connection.
Engineering release and change control
01 / MAP
02 / FREEZE
03 / DEFINE
04 / ROUTE
05 / REQUEST
06 / COMPLETE
07 / RELEASE
08 / REOPEN
An eight-step retention evidence workflow
This is a specification/qualification workflow—not a test procedure for energized or installed equipment.
Define the real loads
List axial pull, side load, cable mass, movement, plug handling, vibration, shock, temperature and fault-duty concerns.
Assign an owner to each force path.Lock the exact terminal
Record manufacturer, full part, revision, poles/levels, rail/support, end stops, covers, jumpers, plugs and locks.
Family-level evidence is not enough.Describe the conductor
Capture material, AWG/mm², construction/class, count, insulation and approved ferrule/lug condition.
Use the exact project wire.Select the conformity basis
Confirm market, product standard/listing, edition, certification category and applicable Conditions of Acceptability.
Do not translate across systems by label.Get the complete report context
Ask for specimen, sequence, force, duration, direction, pass criterion, report date and exact product scope.
Classify setpoint, minimum, result or removal force.Review every interface
Add rail, plug, strain relief, entry, vibration/shock, PCB/housing and fault-bracing evidence as required.
No silent force-path gaps.Translate evidence into controls
Link approved OEM instructions and assembly requirements to the BOM, drawings, terminal plan and incoming criteria.
Store source revision and assumptions.Review every relevant change
A new terminal, wire, ferrule, rail, plug, route, environment or fault duty can invalidate the prior conclusion.
No substitution by visual similarity.
Safety and inspection boundary
A trip, loose wire or intermittent signal is an escalation event
Do not tug-test an energized or unknown circuit, increase torque, substitute a ferrule, add an improvised cable tie or change the terminal to cure a retention concern without the exact product instructions and approved design. Heat, odor, damaged insulation, discoloration, a loose connection, unexplained trips or recurring intermittent signals require qualified review.
For U.S. general-industry work, OSHA 29 CFR 1910.333 generally requires exposed live parts to be deenergized before work unless the employer can demonstrate a stated exception. The applicable lockout/tagout process and qualified-person verification with test equipment are part of treating fixed equipment as deenergized. This article does not authorize energized testing or manipulation.
Use the controlled terminal-block maintenance checklist for safe planning. If the issue may involve damaged parts or recurring behavior, route it to the terminal-block failure-analysis process rather than using a force number as a repair criterion.
Stop and isolate through the approved process: a catalog type-test value is not a field test target, a go/no-go repair criterion or permission to pull on a live conductor.
Common specification and QA errors
Use a hold point instead of an assumption
Most retention failures begin with an incomplete evidence chain or a force-path mismatch—not the absence of one large Newton value.
One force value, no conductor
The figure can be a headline, setpoint or result for another specimen.
Request exact terminal, wire, method and report context.The wire fits, so retention is assumed
Connection capacity and mechanical qualification are separate questions.
Verify conductor conditions and retention evidence.A plug disconnects during handling
The cause can be latch, strain relief, cable route, mating cycles or clamp—not only “terminal strength.”
Review the complete plug/harness system.The block moves on its rail
Rail attachment and conductor retention are independent interfaces.
Use the approved rail, support and end-stop system.A same-rated substitute is accepted
Current, voltage, footprint or clamp style does not establish equal retention or certification.
Rebuild the evidence package as an engineering change.Pull-out data is used for fault bracing
Short-circuit forces can require equipment-specific conductor support beyond component retention.
Obtain equipment instructions and the fault-duty restraint plan.RFQ and incoming-approval checklist
Ask for a traceable retention evidence pack
“Please provide pull-out force” is not enough to identify a specimen, method or load path. These fields let engineering and quality compare the quoted part with the as-built system.
Exact terminal assembly
Manufacturer, full order code/suffix, revision, poles/levels, rail/support, end stops, jumpers, covers, plug, latch and strain-relief accessories.
Actual project wire
Cu/approved Al, AWG/mm², solid/flexible/stranded class, strand construction, count, insulation and approved ferrule/lug condition.
Market and certification route
Applicable product standard/listing, edition, category/file/report and Conditions of Acceptability where relevant.
Full retention conditions
Specimen, conditioning, flexion/pull sequence, force, duration, direction, pass criterion, date and exact product scope.
Define what N means
State whether each number is a prescribed force, machine setpoint, minimum result, actual result or force at removal.
Complete the mechanical map
Rail attachment, plug cycles/latch, vibration, shock, PCB/housing, cable entry/strain relief and fault-bracing evidence as applicable.
Current controlled sources
Installation/termination manual, approved tools, conductor table, accessory instructions, test report, certificate and certification-database record/revision.
As-built traceability
BOM and terminal-plan cross-reference, supplier change notice, substitution limits, incoming approval and review trigger for any changed force path.
Send the exact terminal/order code, accessories and support; conductor material/construction/size/preparation/count; target standard/listing/edition; test method/sequence/force-duration-direction/pass criterion; plug/strain-relief, vibration/shock/temperature/fault-duty context; project market, quantity and required document revision. SENTOP can help compare part-number-specific information and document availability, but the responsible designer/certification process approves the finished application.
Related engineering guides
Keep adjacent decisions separate and traceable
These pages own their specific questions; this article remains focused on retention evidence and mechanical force paths.
Wire strip length
Control the exact pre-insertion conductor preparation without importing a generic millimetre value.
Return to the evidence rulesWire size and construction
Separate AWG/mm² acceptance from pull-out test evidence and service mechanical loads.
Review the answer-first boundaryFerrule conditions
Determine whether the exact terminal accepts the proposed single, twin, bare or insulated ferrule.
Review the ferrule boundaryProduct evidence by market
Keep IEC, UL and other conformity routes within their intended equipment and application scopes.
Review the standards routesSafe inspection planning
Use qualified, deenergized procedures for visible condition and documented maintenance tasks.
Review the safety boundaryFailure-analysis escalation
Investigate heat, movement, damage or intermittent operation without treating a tug as proof.
Review the escalation boundaryPanel-builder controls
Coordinate the terminal with routing, rail/support, cable entry, accessories and fault-duty design.
Map the application force pathsComparable RFQ responses
Request part-specific electrical, mechanical, certification, document and commercial evidence.
Use the retention RFQ checklistFrequently asked questions
Terminal pull-out force FAQ
These answers preserve the same boundaries used in the qualification workflow above.
What is a good terminal block pull-out force?
There is no single good value. A meaningful force result is tied to the exact terminal, conductor material, construction and cross-section, test standard and edition, test sequence, duration, direction and pass criterion. A higher number from a different terminal or wire does not automatically mean a better choice. Compare only equivalent evidence packages.
Is pull-out force an allowable cable load?
No, unless the manufacturer explicitly publishes a separate allowable operating load for the defined system. A pull-out figure is generally a laboratory force or result for a conductor in a clamping unit. It does not automatically cover continuous cable tension, side load, vibration, a plug interface, cable-entry strain relief or fault-current forces.
Does current rating tell me whether a conductor will stay retained?
No. Current, voltage and temperature ratings address electrical and thermal conditions under stated assumptions. Conductor retention is a separate mechanical question. A terminal can have adequate electrical ratings while the intended conductor construction, cable route, vibration environment, mounting or strain-relief system remains unsupported.
What is the difference between a flexion test and a pull-out test?
A flexion test evaluates a specified bending or movement sequence; a pull-out test applies a defined tensile load. A pull-out check may directly follow a defined flexion test, but they answer related, distinct questions. Aging, reconnection and vibration remain separate unless the cited report explicitly combines them.
Is a spring terminal always better than a screw terminal for retention?
No. Connection technology alone is not a force ranking. Screw, tension-sleeve, screwless spring, push-in, lug and plug systems all rely on the exact product design, approved conductor range, accessories, process controls and test evidence. Select the documented terminal-and-wire system, not a generic clamp-style claim.
Do ferrules automatically improve conductor retention?
No. A ferrule changes the termination system. Use one only where the exact terminal manufacturer's current documentation permits or requires it for the actual wire and connection style. The conductor, ferrule geometry, crimp tooling and finished terminal configuration must match the approved evidence and work instructions.
Does a terminal block eliminate the need for cable strain relief?
No. A terminal clamp holds the conductor at a connection point; cable strain relief manages external mechanical loads before they reach that point. Pluggable products can also need separate latching and harness support. Select cable-entry, routing and strain-relief controls for the actual cable mass and handling environment.
Can a passed pull-out report approve a different terminal or wire?
No. Published reports are configuration-specific. A different terminal suffix or revision, conductor class or cross-section, ferrule, accessory, standard edition or environmental profile can change the evidence. Route substitutions through engineering and conformity change control, retrieve current documentation and recheck the final assembly.
What should I ask a supplier to provide?
Ask for the exact terminal, accessories and approved conductor table; applicable standard, listing and edition; complete pull-out and flexion conditions; current installation documentation; and relevant rail-attachment, vibration, shock, plug-cycle, PCB, strain-relief and fault-force evidence. Also request certification conditions, document revisions and substitution controls.
Official and primary references
Sources used for the engineering boundaries
Public pages establish scope and current records; controlled standards, certification files, OEM reports and the locally adopted requirements govern the actual release.
IEC 60947-7-1:2025Current IEC scope for industrial support-mounted terminal blocks and test disconnect terminal blocks for copper conductors.IEC official record
IEC TS 60947-7-5:2021Separate IEC technical-specification route for terminal blocks for aluminum conductors.IEC official record
IEC 60999-1:1999Clamping-unit safety context for defined copper-conductor connections.IEC official record
UL 1059, Sixth EditionActive terminal-block component record; end-product suitability can require additional evaluation.UL official record
UL Connector Certification ServicesPublic overview of North American terminal and connector certification routes.UL Solutions
UL 508A Supplement SA resourcePublic component-requirement resource for controlled industrial-control-panel work.UL Solutions
UL Product iQOfficial certification database for exact component category, file and guide information.UL Product iQ
UL Deadfront Switchboard Application GuideAssembly-level conductor-bracing and fault-force marking boundary.UL Solutions
OSHA 29 CFR 1910.333U.S. general-industry deenergization, lockout/tagout and qualified-person verification boundary.OSHA official regulation
WAGO Laboratory TestsManufacturer explanation separating pull-out, vibration, shock and bending-related evaluations.WAGO official
Weidmüller Mechanical TestingManufacturer description of flexion/pull-out, 60-second force application, rail attachment and separate mechanical tests.Weidmüller official
Weidmüller Pluggable Terminal BlocksProduct-family context for separate locks and strain-relief accessories at detachable interfaces.Weidmüller official
Phoenix Contact Test PrinciplesManufacturer quality-testing framework and test-method context.Phoenix Contact official
Phoenix Contact Mechanical TestsManufacturer explanation of mechanical terminal-block tests.Phoenix Contact official
Phoenix Contact UWV 4 / 3073380Exact model source for the cited tractive-force setpoint/actual-value entries.OEM product page
Phoenix Contact HDFK 25 / 0707743Exact model source for the cited conductor-specific entries.OEM product page
Phoenix Contact PTSA 1.5 / 1434822Exact PCB-terminal source for the IEC 60999-1-referenced entries.OEM product data
Release the evidence—not a headline force
Build a model-specific retention package for the finished assembly.
Send the exact terminal, conductor, test basis, force-path map, mechanical environment and required documents. We will help compare suitable terminal options and identify missing supplier evidence without treating the result as a field tug test or panel approval.
Supplier support does not replace the responsible electrical/mechanical design, adopted requirements, OEM instructions, certification review or qualified safe-work process.
