A current rating for one powered contact does not establish the rating of a multipole connector with several circuits operating together. Before comparing quotations, give each bidder a cavity map, a simultaneous-load schedule and the thermal conditions around the complete connection. Require evidence that covers those conditions, rather than multiplying a headline ampere figure by the number of cavities.
The useful purchasing question is specific: can this identified mating pair, populated with these contacts and conductors, support the engineer-approved load cases in this arrangement? A larger advertised current is valuable only when its supporting configuration matches the project. An unqualified number cannot answer that question.
This guide addresses document review and RFQ preparation for multipole power and mixed power/signal connections. It does not select protective devices, authorize parallel power contacts, establish safe touch conditions or prescribe energized testing. Manufacturer or qualified laboratory evaluations need an engineering-approved plan. Product-specific electrical, mechanical and compliance approvals remain separate release gates.
Distinguish installed positions, loaded contacts and independent circuits
A twelve-position housing may contain twelve contacts, only eight contacts, or a mixture of power and signal contacts. Of the populated positions, some may carry current continuously while others carry it only during a defined operating event. Specify all three counts: available positions, populated positions and simultaneously loaded contacts.
Count the return path as well as the outgoing path. A circuit passing through two connector contacts creates two loaded contact locations. The circuit current should not be divided between those locations merely because there are two of them. A drawing that counts only outgoing conductors can underdescribe the thermal configuration.
Separate a circuit count from a contact count in every spreadsheet. Four independent loads with individual outgoing and return connections can populate eight loaded contacts. Four loads sharing a return elsewhere have a different topology. Purchasing should obtain the approved topology from engineering rather than infer it from the number of equipment functions.
Use cavity identifiers from the manufacturer's drawing and identify the viewing direction. A mating-face view and a wire-entry view can reverse a layout. The housing, contact and keying guide covers the mating-system identity; the additional task here is to put the actual current schedule onto that identity.
Read a current claim together with its loading condition
Samtec's interconnect test-report explanation notes that a single-pin rating may not represent the customer's use and describes reports with different numbers of energized pins at different ambient temperatures. The practical lesson is to request the relevant configuration, not assume the product summary contains every application condition.
A particularly useful original example is Samtec power report 227578, revision 2. For the identified ET60T/ET60S assembly, its page 7 summary lists 70.0 A per power contact with one powered, and 45.0 A per power contact with six powered, under the stated 30-degree temperature-rise and 20-percent derating basis. It separately reports 43.1 A per power contact with all six power contacts and 24 signal pins loaded at 0.95 A each.
Those figures demonstrate why a loading description matters. They are not a current recommendation for another connector, cable harness or enclosure, and they do not establish the permitted current at every ambient temperature. Keep the original report's product identifiers, configuration and applicable curves with any use of its data. Its historical test dates also distinguish it from a new evaluation of a current project.
Do not convert that example into a universal percentage rule. A different contact design, spacing, termination or arrangement needs its own applicable evidence. The RFQ should ask the bidder to show coverage of the required load cases, including assumptions that make a published report usable.
Build a cavity map that captures simultaneous operation
Create a configuration identifier, such as MC-01, and give the drawing a revision. For every cavity record its circuit name, contact part number, conductor identity, expected current and operating case. Include unused cavities explicitly so that a blank cell does not conceal an unreviewed position.
Define meaningful operating cases instead of listing unrelated maximum currents. Examples might include normal operation, a permitted simultaneous start event, charging, service mode or a specified recovery sequence. Engineering must determine which cases apply and whether their durations and combinations are credible.
A schedule saying that two loads are mutually exclusive needs a documented control assumption. Record the function that enforces that condition and the configuration or software version to which it applies. If a later software change permits both loads together, the connector evidence may need review even when its hardware is unchanged.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Map field | What the buyer supplies | What the bidder must identify |
|---|---|---|
| Physical location | Cavity number and drawing view | Matching contact location in the evidence |
| Contact population | Populated, unused or reserved | Actual sample population and contact references |
| Circuit demand | Current for each defined operating case | Covered current and duration for each location |
| Return arrangement | Separate, shared or external return | Corresponding loaded-contact count and map |
| Conductor boundary | Both sides, termination and cable identity | Conductor or board setup used for the rating |
| Simultaneity | Which circuits can run together | Applicable group-loading configuration |
| Future option | Reserved cavities and planned function | Whether future population is outside approval |
A reserved cavity is a controlled design feature, not a free future power channel. Record whether it was empty during the evaluation and whether filling it later requires a new review. That is easier to manage when the approved population drawing accompanies the purchasing specification.
Separate local ambient, temperature rise and material limits
The temperature around a connection is not necessarily the room temperature outside its enclosure. Ask engineering to identify the local ambient condition and its basis, including nearby equipment, mounting position and intended ventilation. A buyer should not substitute the site's weather forecast for the relevant equipment condition.
Temperature rise describes a difference above the specified ambient. An absolute component temperature limit describes a different boundary. Keep both fields visible, and ask the supplier which measured location or component sets the applicable limit in the proposed arrangement.
Samtec's current-carrying-capacity explanation describes a controlled temperature-rise assessment and a derating step in its stated approach. That is evidence of the manufacturer's method; it is not permission to apply the same factor to every catalog rating. Identify whether the offered value is a measured result, a base curve or an already derated published allowance.
The distinction can prevent applying a factor twice or overlooking one entirely. If a quotation says "tested current" and a graph says "derated current," ask the bidder to reconcile them in writing. Do not resolve the difference by choosing whichever number produces a more attractive price comparison.
Preserve the conductor and mounting boundary of the evidence
For a cable-to-cable assembly, identify the conductor on both sides of the mating interface, including size, construction and termination method. For a board-mounted connection, request the relevant board and termination arrangement. A report for one physical arrangement is not automatically evidence for another.
The HARTING product page for article 97000002344 explicitly ties its stated rated current to measurement at 20 degrees Celsius and directs readers to the derating curve. This is a model-specific example of a condition attached to a catalog value. It does not establish suitability for a SINAWATTS project or another HARTING article.
Include cable routing, enclosure location and adjacent heat sources in the drawing package when they are part of the application. Ask the manufacturer to identify differences between its reference arrangement and the proposed installation. Record those differences as review items rather than silently treating them as acceptable.
The battery-cable bundling and hot-compartment guide addresses the connected cable's separate evidence needs. Connector acceptance does not approve the harness, and a cable rating does not approve the mating interface. Coordinate the two decisions without inventing a universal correction factor between them.
Compare power and signal loading without losing the signal function
A mixed connector may carry high-current paths alongside sensing, communications or auxiliary circuits. Do not label the smaller circuits as thermally irrelevant without knowing their actual loading. Show their populated positions and operating currents in the schedule given to the supplier.
At the same time, a thermal report does not establish signal integrity, contact resistance stability, noise immunity or control-system reliability. Those are separate requirements. Keep the thermal acceptance line linked to the other relevant evidence so a supplier does not interpret approval of current carrying as approval of every connector function.
Where the vendor uses a reduced signal-current condition in a mixed-load report, preserve that condition. A project with different signal loading should be compared against the applicable manufacturer explanation, not a recollection that "the report already tested power and signals together."
Ask how the evidence treats unused signal positions and optional contacts. A quote that changes the population or combines previously separate functions needs an explicit review of the resulting configuration. Small commercial substitutions can otherwise bypass the very loading assumptions used to shortlist the product.
Review unequal loading and duty without inventing a formula
Published reports often use controlled groups with equal currents because those arrangements can be reproduced. A real application may use unequal currents across positions. Submit the actual schedule and ask the manufacturer to identify which published configuration covers it, or which additional analysis or evaluation is necessary.
Do not average the currents across all cavities and compare that average with a per-contact rating. The resulting arithmetic loses the individual locations and currents. An empty cavity should not create additional allowable current in another cavity without an applicable documented basis.
Similarly, a short peak is not automatically covered by a continuous rating or by a casually calculated duty-cycle average. Provide the specified duration, repetition interval, starting condition and combinations of loads. The design authority and manufacturer must determine whether the available evidence supports that duty.
Separate ordinary operating cases from fault behavior. Current-carrying evidence is not short-circuit withstand evidence, interruption capability or protection coordination. The procurement comparison should identify these as separate deliverables, particularly when a bidder presents one successful thermal evaluation as a complete electrical qualification.
Work through a hypothetical eight-position load comparison
The following map, currents, offer values and document references are invented solely to demonstrate an RFQ review. They are not ratings, test results or design instructions for a real product. Assume engineering specifies three isolated circuits, each with its own outgoing and return contact, in an eight-position housing.
In operating case LC-01, circuit A requires 8 A through cavities 1 and 2; circuit B requires 8 A through cavities 3 and 4; circuit C requires 2 A through cavities 5 and 6. Cavities 7 and 8 remain empty. The case therefore has six loaded contacts, with individual currents retained in the record.
The three circuit currents total 18 A, but that total does not describe a connector rating. Adding current entries for both outgoing and return contacts would produce 36 A in a spreadsheet, which is also not a connector capacity. Neither total can replace the six-location load map.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Hypothetical offer | Evidence presented | Decision for LC-01 |
|---|---|---|
| A | 12 A per contact with only one contact powered | Hold: six-contact case is not demonstrated |
| B | 9 A per contact with all eight positions loaded, matching terminations and required thermal condition | Advance only after manufacturer confirms the proposed six-position population and unequal schedule are covered |
| C | 10 A with six contacts loaded, but a different conductor and open reference mounting | Hold: count matches, installation evidence does not |
| D | Manufacturer application statement referencing LC-01, its cavity drawing and the matching report | Review the stated coverage and limitations; close remaining electrical and mechanical gates separately |
Offer B is a stronger starting point than A, but the buyer still obtains the configuration statement. Offer D makes the evidence relationship visible rather than depending on an informal interpretation. A and C remain eligible to provide missing evidence or revise the proposed assembly.
Record one exception without rewriting the requirement
Suppose offer C later supplies the correct conductor data but leaves the mounting difference unresolved. Update exception EX-03 to show "conductor mismatch closed; enclosure applicability open." Link the new document and date to that exception. Do not change the project drawing to resemble the vendor's laboratory setup merely to clear the comparison sheet.
If engineering decides to alter the enclosure or mounting, issue a new project revision and request confirmation against it. Keep the original offer and review history. This lets purchasing distinguish a legitimate design change from an unexplained acceptance of missing evidence.
Create a report-to-configuration evidence index
Use one row per required operating case. Link the case to its cavity drawing, current schedule, exact mating parts, contact population and environmental assumptions. Then list the report page, curve, application statement or approved evaluation plan that supports it.
A report title alone is insufficient. A long report can contain several populations, conductor sizes and test conditions. Include the applicable figure or page and explain the mapping in one sentence. The reviewer should not need to reconstruct which of several curves the sales quotation intended.
Distinguish three outcomes: demonstrated within the stated scope, not yet demonstrated, and explicitly excluded by the product instructions. These outcomes require different actions. Missing documentation may be supplied; an excluded arrangement requires an approved design alternative or different product, not another signature on the same incomplete form.
Ask each supplier to state limitations in its own technical response. Keep unresolved assumptions out of the purchase-order acceptance paragraph. A precise hold is more useful than a blanket rejection because it tells the bidder what evidence would allow the offer to re-enter the comparison.
Agree sample work around traceable configurations
If existing evidence does not cover the proposed arrangement, have engineering define the evaluation objective before samples are ordered. Identify the configuration, required operating cases, measurement locations, environmental boundary and acceptance criteria. The manufacturer or qualified laboratory should confirm the method and responsibilities.
Record the sample part numbers, contact population, terminations, conductor identities and build revision. Include photographs or controlled drawings where they clarify the evaluated arrangement. A sample report that cannot be tied to the proposed bill of materials cannot support a dependable purchasing release.
Ask for individual observations and deviations to remain traceable. A summary marked "pass" should reference the underlying records and limits. If a contact or termination is replaced during the evaluation, retain that event and determine whether the resulting sample still represents the originally agreed configuration.
This is a request for professional evidence, not an instruction for a buyer to apply current to an unknown connector. Do not use an operating battery installation as an informal qualification bench. Any energized work needs the responsible organization's approved procedures and competent personnel.
Send your cavity drawing, simultaneous-load schedule and connector evidence for an RFQ review. Include unresolved assumptions so the discussion can focus on the exact configuration rather than an unsupported ampere target.
Price the evidence gap separately from the connector unit
Ask for the quoted assembly boundary: mating halves, contacts, accessories, terminations and any evaluation or documentation work. A low unit price may cover only a housing or one half of a connection. The review should compare the same deliverables before treating two prices as competing offers.
Separate technical questions from commercial commitments. Request written confirmation of sample scope, production quantity, tooling responsibilities and schedule when those details are needed. This article does not establish SINAWATTS stock, minimum order quantity, price or lead time for a particular configuration.
Where a supplier proposes a lower-cost alternate contact, require the relevant evidence mapping to be updated. A shared fit or conductor range does not by itself make the original thermal evidence transferable. The cost comparison should show any resulting validation work rather than concealing it as an assumed equivalent.
For a broader assembly inquiry, the OEM/ODM service page provides a project-discussion entry point. The RFQ still needs explicit agreement on supported work and deliverables; the existence of a service page is not proof of a particular testing capability.
Freeze the approved population and control later changes
Attach the accepted cavity map and operating-case schedule to the released drawing package. Identify the manufacturer documents and revisions supporting each approved case. Receiving and assembly teams should be able to compare delivered identifiers with that package without interpreting a thermal graph themselves.
Define review triggers that include contact substitutions, conductor changes, population changes, mounting changes and newly simultaneous operating modes. Assign an owner to decide whether the change is within the documented boundary or needs additional evidence. A commercial equivalence statement should not silently overrule this process.
Keep future options outside the released configuration until reviewed. If cavities reserved for a later accessory become populated, reference the original approval and record what has changed. This prevents a connector selected for an earlier, lighter arrangement from acquiring a new load simply because physical space remains.
Use the knowledge center to connect this thermal review with the project's separate mating, retention and cable requirements. The final release is a coordinated set of decisions, each supported by the evidence appropriate to that question.
Make the acceptance boundary usable by production
Write an acceptance note that names the covered operating cases, rather than merely stating that the connector is approved. For example, a document-only approval may say that MC-01 revision B is supported for LC-01 and LC-02 under the referenced mounting arrangement, with future population of reserved cavities excluded pending review. That is a scope statement, not a substitute for engineering limits.
Link that note to the bill of materials and the relevant supplier response. A production order should not have to infer which of several historical contact variants was acceptable. If the purchasing system uses abbreviated descriptions, retain a controlled attachment with the complete references and make it part of the order's technical requirements.
Also state what must be reported before substitution. Changing a wire size, moving a loaded circuit or adding an option may leave the housing unchanged while changing the evidence boundary. A clear notification requirement gives the supplier a practical way to raise that issue before assembly, instead of leaving receiving to discover it afterward.
FAQ
Is a multipole connector rated per contact or for the whole connector?
Read the exact manufacturer's definition. A value may be stated per contact under a specified powered-contact configuration. Record both the unit and the loading condition. Do not multiply a single-contact value by cavity count and call the result an assembly rating.
Does an unused cavity increase the current available in the remaining contacts?
Not automatically. Request applicable manufacturer evidence for the proposed population and layout. Empty positions may make the application different from a fully populated reference, but purchasing should not invent a capacity increase or a percentage credit for them.
Can positive and return contacts share one current allowance?
A separate outgoing and return contact each carries the circuit current in that topology. Show both loaded locations on the map. Do not divide the circuit current by two simply because two contacts complete the path; engineering must approve the actual circuit arrangement.
Can I use the average current across all contacts for comparison?
An average can hide a heavily loaded location and cannot replace the current schedule. Give the supplier individual currents, simultaneous operating cases and the physical map. Request a documented explanation of which published or project-specific evidence covers that schedule.
Does a temperature-rise report also approve interruption under load?
No. Current carrying, fault withstand and make/break duties are separate questions. Obtain the applicable switching and protection evidence for the intended function. A connector should not be treated as a disconnecting device simply because its contacts carried current in a report.
What should an RFQ include when the available curve does not match?
Send exact mating parts, contact and conductor references, cavity population, current cases, duty, local thermal conditions and mounting details. Ask the manufacturer to identify the evidence gap and propose the appropriate review or evaluation. Keep approval on hold until the defined requirement is supported.
Can SINAWATTS confirm price and delivery from the current target alone?
A current target does not define a complete assembly. Provide the configuration and evidence requirements, quantity, destination and needed deliverables so the actual scope can be reviewed. Price, availability, minimum order quantity and delivery require project-specific written confirmation.
Send a loaded-contact connector RFQ
A useful RFQ contains the same picture of the connection for purchasing, engineering and the bidder: exact parts, populated positions, individual currents and simultaneous operating cases. Include the required environment and evidence index, then identify any unresolved configuration differences explicitly.
Send your multipole connector load map and matching-report requirements. A reviewable configuration gives suppliers a concrete question to answer and gives buyers a defensible basis for comparing the resulting offers.