How to Propose an Equivalent Alternative for a Client-Specified Multi Cable Transit Brand?

Every month, our sales engineers receive RFQs that name one multi cable transit brand and ask for an equivalent alternative marine bulkheads ¹. The named brand is late, expensive, or both.

An equivalent alternative for a client-specified multi cable transit brand is proposed by proving dimensional fit with the existing frame cutout, matching fire, IP, and pressure certifications with test reports, showing total cost of ownership savings, and offering free validation samples and CAD files for client verification.

That answer sounds simple. In practice, each of those four steps has traps. I have watched good proposals fail on one missing test report or one wrong stay plate thickness. So I will walk through each step the way our own engineers do it when we build a second-source package for a cable sealing system. I will start with dimensions, because that is where the client looks first.

How can I prove dimensional compatibility with the client's specified 120-frame system before submitting my proposal?

On our production line, every TSC module batch is gauge-checked against the 120-frame standard before it leaves Shaanxi. That check is what makes drop-in claims real.

Prove dimensional compatibility by comparing frame opening width, depth, module stack height, stay plate thickness, and compression unit travel against the client's 120-frame drawing, then confirming with a cross-reference chart, STEP files, and a physical fit test using free validation samples installed in the same cutout.

The 120-frame convention is the reason second sourcing works at all in this industry. Most modular transit frames used in switchgear, BESS containers ², modular data centers, and marine bulkheads follow it. The convention fixes the internal opening height, the frame depth, and the size increments of the modules that stack inside. It does not fix the rubber compound, the core design, or the compression hardware. So a module can be dimensionally identical and still perform differently. Keep that distinction in mind. Dimensions get you into the frame. Performance gets you through the audit.

What to measure, and how to verify it

I recommend a written checklist. Our engineers use one like this when they prepare a cross-reference chart from an existing model number to a DEWIN model.

The cutout objection

A common objection is that the cutout is different. In most drop-in cases it is not. If the client keeps the existing frame, only the modules, stay plates, and compression unit change. The bulkhead or panel wall stays untouched. If the client replaces the whole frame, we match the outer flange dimensions and bolt pattern so the weld or bolt-in cutout stays the same. Either way, no structural rework is needed.

Spare capacity and the cable schedule

Our step-core, halogen-free EPDM ³ modules adapt to a range of cable diameters within one module size. That reduces the number of module sizes on site. It also lets us show the client the same or better spare capacity in the same frame, so future cable additions do not require a new transit. Put that number in the proposal. Skeptical buyers count spare positions.

What certification and test documentation do I need to justify an equivalent MCT brand to a skeptical client?

A purchasing engineer in Europe once replied to our first quote with one line: send the test reports first, then we talk. We did, and the project moved.

To justify an equivalent MCT brand, provide third-party fire test reports (A-0/A-60 or the required rating), IP68 ingress protection certificates, watertight and gas-tight pressure test results, ISO 9001 and IATF 16949 quality system certificates, factory approval evidence, material datasheets, and a clause-by-clause technical data sheet comparison.

Documentation is where most equivalent proposals live or die. The client's consultant will not read a brochure. They will read a specification clause, then look for the document that satisfies it. So build your package in that order: clause first, evidence second, difference explained third.

Map every specification clause to a document

The two hardest objections, and how I answer them

The first objection is that the spec names one brand, so no substitution is allowed. My answer is to read the contract language. Many specifications name a basis of design and include an approved-equal or or-equal clause. If that clause exists, an equivalent proposal is a normal project specification deviation, not a breach. If the clause does not exist, say so early and ask the client whether they want to open one. Do not guess.

The second objection is harder. The client says the transit was tested as a full system. They are right. A fire-rated penetration is certified as frame, modules, stay plates, and compression unit together. So we never propose mixing our modules into another brand's frame for a fire-rated wall unless that exact combination has a test behind it. Instead, we propose the complete tested system. On non-fire-rated panels and enclosures, where the requirement is sealing and ingress protection only, module-level substitution is easier to defend. Know which case you are in.

Write a comparison, not a pitch

The core of the package is a technical data sheet comparison, clause by clause. Where the values match, say so. Where they differ, explain why the difference does not reduce performance in this application. That honesty is what a data-driven buyer is looking for.

How do I calculate and present the real cost savings without appearing to compromise on quality?

The trade-off I weigh on every quote is simple: unit price wins the first meeting, but total cost of ownership ⁵ wins the approval. We price for the approval.

Calculate real savings by building a total cost of ownership model: component price (typically 40–60% lower for a drop-in second source), landed cost with freight and duty, installation hours, spare module cost, re-entry time for future cables, and lead-time risk, then present it beside unchanged certification evidence.

There is a trap in how cost gets presented. If the first page of your proposal is a price, the reader assumes you are selling price. If the first page is a certification matrix and the price comes on page four, the reader assumes you are selling a qualified second source. Same numbers, different conclusion. Order matters.

Build the model on lines the client already tracks

Present the savings in three steps

1. Confirm technical equivalence first. Get written acceptance of the certification matrix before any cost discussion.
2. Show the total cost of ownership table, not just the unit price. Let the client fill in their own installation and re-entry hours if they prefer.
3. Frame the savings as risk reduction. Supply-chain volatility and long lead times have pushed more projects toward value-engineered substitutions. A qualified second source protects the schedule even when the primary brand is available.

Add the ESG line if the client has targets

Many European integrators now report on material choices. Our modules use halogen-free EPDM, which supports low-smoke and low-toxicity requirements in enclosed BESS containers and data halls. Put that on the same page as the cost model. It shows the alternative was selected for the application, not just for the invoice.

Can I request free validation samples and CAD files to de-risk my equivalent alternative proposal?

The lesson we learned in our first export years was simple: a STEP file and two free modules close more qualifications than any brochure. We now send both by default.

Yes. A credible second-source supplier should provide free validation samples of the proposed modules, CAD or STEP files of frames and modules, and a model cross-reference chart, so you can run a physical fit test, update drawings, and complete a project specification deviation before committing to a purchase order.

A sample request is not a favor. It is part of a normal supplier qualification. If a supplier hesitates to send a free module or a native CAD file, that tells you something about their confidence in the fit. On our side, we treat the sample as the last step of the dimensional proof, so we send it before the client asks.

A validation process that produces evidence, not opinions

1. Send the supplier the frame model, the cable schedule, and the wall or panel type. The supplier returns a cross-reference chart listing the existing model beside the proposed model for every position.
2. Request STEP files ⁶ of the frame, each module size, stay plates, and the compression unit. Overlay them on your existing assembly drawing. Any interference shows up before the sample ships.
3. Receive the free validation samples. Install them in the actual frame with real project cables, not test rods. Complete the full compression cycle and record bolt torque and stack height.
4. Photograph the installed transit and file it with the project specification deviation request. The photo plus the certification matrix is what the consultant needs to sign.
5. Order a pilot quantity for one transit or one panel, then scale.

What to ask for, and why each file matters

Custom sizes and private label

When a project has a non-standard cutout or a cable that falls outside standard module ranges, in-house mold making lets us produce a custom size without long tooling delays. For OEM integrators, private-label production means the module can carry the integrator's marking while the underlying test documentation stays with the same certified product. Ask about both during the sample stage, not after the order.

Fazit

The specified brand is late or overpriced, and waiting costs the project every week. An evidence-led equivalent proposal — dimensions, certificates, cost model, samples — solves that without giving up compliance.

Fußnoten

1. IMO safety standards for fire protection on marine bulkheads and penetrations. ↩︎

2. IEA report on grid-scale storage and BESS technology for energy infrastructure. ↩︎

3. Technical overview of EPDM rubber properties and its use in industrial sealing. ↩︎

4. Official IEC page explaining the IP68 ingress protection standard for sealing performance. ↩︎

5. Economic concept used to evaluate the long-term value of industrial equipment. ↩︎

6. ISO homepage for international standards including CAD data exchange formats like STEP. ↩︎