OEM Surge Protective Device RFQ Checklist: 12 Specifications Buyers Should Send to the Factory

1. Why incomplete RFQs slow OEM projects down

An OEM surge protective device project is not a catalogue purchase. The buyer is asking a factory to build a product — with the buyer's brand, packaging and approval requirements — so the specification has to be complete before anything meaningful can be quoted. When key information is missing, the SPD manufacturer has to guess, and guessing produces quotations that later have to be reworked.

The most common gap is not technical at all: it is the target market. Two buyers can order the same electrical design, but if one sells into a market with specific certification requirements, the factory needs to know that before confirming feasibility. A second common gap is the earthing system, which changes the SPD connection mode; without it, the number of poles cannot be fixed.

A third gap is quieter but just as expensive: unstated branding and packaging assumptions. If the buyer expects retail-ready boxes and the factory quotes standard export cartons, the gap surfaces after sample approval — when it costs the most to fix. Standardizing the SPD RFQ closes all three gaps at the start.

This article turns the request-for-quotation process into a checklist of twelve specifications, following the sequence used on the OEM/ODM program page and the factory introduction: application first, electrical parameters second, hardware and compliance third, commercial items last. An SPD RFQ built this way can normally be answered in one round instead of several.

2. The 12 specifications at a glance

The diagram below groups the twelve items the way a factory engineering team reads them. Items 1–4 describe where the device works and what system it connects to; items 5–8 describe the device itself; item 9 covers the compliance evidence and item 10 the branding; items 11–12 describe the commercial frame of the project.

3. Items 1–3: Application, voltage, earthing

1. Application and installation environment

Where will the device be installed — a distribution board in a building, a photovoltaic combiner box, a charging station, a control cabinet on a machine? The application determines the product family to be quoted, and the environment (indoor, outdoor, corrosive, high-vibration) determines enclosure and material options. A surge protector supplier can narrow the range from this item alone, but not further without the next two.

2. System voltage and frequency

The nominal voltage and frequency at the installation point (for example 230/400V, 50Hz) set the maximum continuous operating voltage Uc that the device needs. This is the value most often missing from incomplete inquiries, and without it no responsible factory will confirm a model.

3. Earthing system

TT, TN-S or TN-C-S changes the connection mode: a TN-S board normally uses 4-pole or 3+1 protection between phases, neutral and PE, while a TT system places different emphasis on the N–PE path. Stating the earthing system up front fixes the pole configuration before the surge ratings are discussed.

4. Items 4–6: SPD type, surge ratings, poles

4. SPD Type and location

Type 1 (impulse), Type 2 (induced surges) or combined Type 1+2 — the choice normally follows the location in the installation: service entrance, sub-distribution board or equipment level. This selection logic is not vendor-specific: it is the core subject of IEC 61643-12, the selection and application principles for SPDs on low-voltage power systems, which the factory's recommendation normally follows. The same application note applies across the AC power SPD and Signal & Data SPD categories, where the signal equivalents are defined by interface instead.

5. Surge parameters

The discharge ratings and the voltage protection level define what the device withstands and what it lets through, and the standard terms are worth using precisely. Uc is the maximum continuous operating voltage the device tolerates indefinitely; Iimp (Type 1) is the impulse current on the 10/350μs waveform, while In and Imax (Type 2) are the nominal and maximum discharge currents on the 8/20μs waveform; Up is the voltage protection level the device holds during those tests. The requested values should come from the site's risk assessment or the end user's specification — and In and Imax belong together: a request stating Imax alone gives the factory no steady-stress reference.

6. Number of poles and connection mode

How many protected poles, and how the neutral and PE are handled (for example 3+1). This follows from items 2 and 3, which is why those are listed first: a complete voltage and earthing statement usually makes the pole count self-evident.

5. Items 7–8: Signaling, enclosure, dimensions

7. Remote signaling contact

Many distribution boards monitor SPD status centrally. If the building management or SCADA layer needs a signal, the RFQ should state the contact type (for example changeover contact) so the quoted variant includes the terminals. This is inexpensive to specify up front and disruptive to add later.

8. Enclosure, dimensions and mounting

For DIN-rail devices, the module width and profile determine whether the device fits the board; for box-type devices, the enclosure material and ingress protection matter for outdoor or dusty environments. A drawing or the available panel space is enough for the factory to confirm fit.

Two dimensions are worth stating even when the layout is still open: the maximum module count per row, and any height limit inside the enclosure. Information that costs the buyer one sentence can otherwise cost a redesign round at the factory.

6. Item 9: Standards and test reports

The RFQ should name the standard and edition the project works to, and request the model-specific test report as part of the quotation package. For AC power devices the usual reference is IEC 61643-11, the standard for SPDs connected to AC low-voltage systems, whose general requirements and test methods are collected in IEC 61643-01, the common part for all SPDs. For signal and data devices, IEC 61643-21 applies.

When the report arrives, three points settle whether it supports the offer: the model number matches the model being quoted, the test class (Class I / II tests) matches the SPD Type requested, and the standard edition cited is the one the project requires. The full review process — the traceability chain from standard to report to model — is covered in our IEC 61643-11:2025 buyer's guide.

Two boundaries keep this item honest. First, a standard cited on a datasheet is a design reference, not evidence — the report naming the model is the evidence. Second, the certifications that apply in the destination market are confirmed case by case: an SPD manufacturer can state which approvals a project can carry only after reviewing the target market, which is item 12.

7. Item 10: Logo, labelling and packaging

OEM branding is where a parts order becomes a product program. The RFQ should state whether the buyer's logo is printed on the device, what the rating label needs to show (buyer name, model code, electrical data, approval marks), the documentation language, and the packaging format — individual colour boxes, carton quantities, barcodes if any. Each of these touches production planning and cost, so they belong in the quotation, not in a later negotiation.

8. Items 11–12: Quantity and target market

Annual quantity and phasing (pilot lot, first order, repeat schedule) let the factory plan material procurement and quote realistic terms. The target market determines which certifications the project needs to carry, which in turn can affect components and cost. Neither value is needed to start the technical discussion, but both are needed before a firm quotation — and no responsible surge protector supplier will state a delivery schedule before quantity, branding and approval scope are fixed.

9. The RFQ template

The table below is the checklist in a form that can be pasted into an email. The middle column is what the buyer states; the right column is what the factory does with it.

Not every project needs all twelve rows filled on day one. A typical first inquiry carries the six technical items plus the quantity range, and the branding and market rows arrive when the design stabilizes. What matters is that the open items are visible as open, so the factory quotes around them deliberately instead of filling the blanks with assumptions.

10. Common specification errors

Five gaps account for most of the clarification rounds a factory sends back:

• System voltage written where Uc is needed. The two are related, not equal; the factory still needs the circuit voltage to size Uc with margin.
• Imax quoted without In. The two describe different stress levels and are evaluated together.
• Up specified without the test class or waveform. A protection level without its reference test is not comparable between datasheets.
• Earthing described as "three-phase" instead of TT / TN-S / TN-C-S. Phase count does not fix the connection mode.
• "DIN-rail mount" without the available module width. Fit cannot be confirmed without a dimension.

11. Insufficient vs complete: an example

The same project, quoted twice. Inquiry A is the version every factory receives regularly: a request for "a surge protector" with no further detail. Inquiry B is the same request with the twelve points filled in.

The practical difference is not just speed. When the SPD RFQ is complete, the quotation that comes back is a commitment the factory can stand behind: a named model, a datasheet with the right ratings, a report scope, and commercial terms that reflect the real quantity and branding. When it is not, the first quotation is an estimate built on assumptions, and every clarification round re-opens pricing, certification scope or delivery.

Walk through Inquiry B once to see the points working together: application (building board) and earthing (TN-S) fix the 3+1 connection mode; the system voltage (230/400V) fixes the Uc class; Type 2 at the main board with In 20kA selects the variant inside that class. The remaining items turn the quote from a product into a project. Nothing in that list took more than one line to write, and together they removed every round of guesswork from the reply.

12. What happens after you send the RFQ

13. FAQ

Why does an OEM inquiry need more information than a catalogue purchase?

Because the factory is building the product for your brand: logo, labelling, packaging and destination approvals are part of the specification, and each of them can change the quotation. A catalogue purchase fixes all of those in advance; an OEM project defines them per order.

Which of the twelve items matter most for the technical selection?

System voltage, earthing system and SPD type. Those three fix the electrical family of the device; the surge parameters then select the variant. The remaining items shape hardware, compliance and commercial terms.

Does stating the target market change the product?

It can. Different markets carry different certification requirements, and those can affect components, label content and cost. This is why the market is item 12 rather than an afterthought: it is confirmed case by case before a firm quotation.

Can the factory state certifications and lead times in the first reply?

Normally only after the review. Certification scope depends on the model and the target market, and delivery depends on quantity, branding and material planning. A responsible reply confirms these per project rather than quoting them generically.

What if some of the twelve items are not yet fixed?

Send what is fixed and mark the rest as open. The factory can often quote a model range against the closed items and list the open ones as options, keeping the project moving while the design matures.

Is the checklist the same for signal and data SPDs?

The structure is the same, but the technical items change: interface type and line voltage replace the pole configuration, and IEC 61643-21 replaces the AC power standard. The commercial items are identical.