SPD Uc and MCOV values such as 150V, 275V, 320V, 385V, 440V, and 480V are common in catalogues and datasheets. This guide explains what these ratings usually mean, where buyers often see them, and why they should not be treated as fixed country rules.
Resposta rápida: Uc and MCOV are continuous voltage ratings, not surge current ratings. A rating such as 275V, 385V, or 480V tells buyers the maximum continuous voltage the SPD protection mode is designed to withstand. It does not, by itself, confirm whether the SPD is suitable for a specific project, country, earthing system, or certification route.
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What This Page Explains
This article explains common SPD Uc and MCOV rating values from a catalogue and market-facing point of view. It helps buyers understand why they often see values such as 150V, 275V, 320V, 385V, 440V, and 480V in AC SPD documents.
It is not a project-specific selection calculation page. If you need to calculate SPD Uc for TN, TT, IT, or split-phase systems, use the calculation guide linked at the end of this article. If you need to choose between 275V, 320V, 385V, and 440V for distribution boards, use the dedicated selection guide.
Importante: the values below are common catalogue references. They are not fixed country rules, and they should not replace the approved SPD datasheet, local electrical design, earthing system review, or certification requirement.
Common SPD Uc and MCOV Rating Values
The table below gives a practical overview of common Uc and MCOV rating ranges. The exact value depends on the product family, standard, service voltage, protection mode, and target market.
What Uc and MCOV Mean on SPD Datasheets
In IEC-style SPD datasheets, buyers usually see Uc, or maximum continuous operating voltage. In UL-style documents, buyers usually see MCOV, or maximum continuous operating voltage. Both terms help buyers check whether an SPD can remain connected to the real service voltage without abnormal continuous stress.
The wording matters because it is linked to the target market, datasheet style, label wording, and approval route. Writing MCOV on a document does not automatically mean the SPD is UL listed. Certification status must be confirmed separately.
Practical rule: read Uc or MCOV together with service voltage, protection mode, earthing system, connection mode, Up, In, Imax, and certification documents. Do not judge an SPD only by the catalogue voltage number.
How to Read Catalogue Rating Values
A catalogue value such as 275V or 385V does not mean the SPD is only for one country. It also does not mean the same rating can be copied into every system with a similar nominal voltage.
The rating must be checked against the voltage that each SPD protection mode will continuously see. For example, an SPD connected line-to-neutral is not reviewed in exactly the same way as one connected line-to-earth, neutral-to-earth, or in a 3+1 configuration.
| What buyers see | What it does not prove | What to confirm instead |
|---|---|---|
| 275V printed in a catalogue | It does not prove the SPD is suitable for every 230/400V project. | Check earthing system, connection mode, grid condition, and datasheet. |
| 385V printed on a model code | It does not prove the SPD gives better protection than a lower Uc option. | Check Up, protected equipment sensitivity, and continuous voltage margin. |
| 480V MCOV in a UL-style file | It does not prove the product is UL listed by itself. | Check certification file, marking requirement, and service voltage. |
| Same rating from different suppliers | It does not prove the products have the same performance. | Compare Up, In, Imax, SCCR/Isccr, SPD type, test report, and construction. |
What Buyers Should Confirm Before Ordering
Uc and MCOV are important, but they are only one part of SPD selection. Before confirming an order, buyers should check the rating together with the real system and documentation requirement.
- Target market: IEC-style, UL-style, GB/T-style, or local export project.
- Service voltage: 120V, 230/400V, 400/415V, 480V, or other system voltage.
- Protection mode: L-N, L-PE, N-PE, line-to-ground, 3+1, 4P, or another arrangement.
- Earthing system: TN-S, TN-C-S, TT, IT, split-phase, or project-specific system.
- Uc or MCOV value shown on the label and datasheet.
- Voltage protection level Up and downstream equipment sensitivity.
- SPD type, discharge current ratings, and backup protection requirement.
- Certification status, test report, and approved product family.
- OEM model code, packaging wording, and datasheet language.
Send us your target market, service voltage, required Uc or MCOV value, and datasheet requirement. We can help check whether the rating wording and product documents are aligned before OEM production or bulk ordering.
Check SPD Rating RequirementCommon Mistakes When Comparing Uc and MCOV Ratings
Mistake 1: Treating the rating as the nominal system voltage
Uc or MCOV is not the same as the nominal system voltage. It is the maximum continuous voltage applied to the SPD protection mode. The rating must be higher than the normal continuous voltage the SPD may see.
Mistake 2: Thinking a higher rating is always better
A higher Uc or MCOV gives more continuous voltage margin, but it may also affect the voltage protection level. Buyers should compare the rating with Up and the equipment being protected.
Mistake 3: Comparing only the voltage number
Two SPDs with the same Uc or MCOV can still have different discharge current ratings, protection levels, certifications, internal construction, and application limits.
Mistake 4: Assuming MCOV wording means UL approval
MCOV is common in UL-style documents, but wording alone is not certification. Buyers must check the actual listing, test report, approval status, and product marking requirement.
Mistake 5: Using AC Uc / MCOV values for DC or solar PV SPD
This article explains common AC SPD Uc and MCOV values. Solar PV and DC SPD selection uses Ucpv and different system logic. Do not copy AC rating values into DC or PV applications.
FAQ: Common SPD Uc and MCOV Ratings
A tensão do sistema de 275V é a mesma que a de 230V?
No. 275V is a Uc rating commonly seen in IEC-style AC SPD catalogues. It is not the same as the nominal 230V system voltage. It should be checked against the actual protection mode, grid condition, earthing system, and datasheet.
Por que alguns catálogos mostram 255V e outros mostram 275V?
Different product families, standards, markets, and design choices may use different catalogue values. Buyers should not compare only the number. They should also check Up, In, Imax, SPD type, connection mode, and certification documents.
O SPD de 385V é melhor do que o SPD de 275V?
Not automatically. A 385V SPD can tolerate a higher continuous voltage, but that does not always mean better protection for sensitive equipment. The correct rating depends on the system voltage, grid condition, earthing arrangement, protection mode, and Up value.
O que significa 480V MCOV?
480V MCOV means the SPD is marked for a maximum continuous operating voltage of 480V in the relevant protection mode or product configuration. Buyers still need to confirm service voltage, system configuration, product marking, and certification status.
O MCOV significa que o SPD está listado pela UL?
No. MCOV wording is common in UL-style documents, but it does not automatically prove UL listing or approval. Certification must be confirmed through the actual approval file, test report, and product marking.
Pode-se usar uma classificação Uc ou MCOV para todos os países?
No. A rating value may appear in many markets, but the final selection depends on service voltage, earthing system, connection mode, temporary overvoltage condition, local requirement, and product datasheet.
Are these ratings suitable for solar PV SPD?
No. This article is about common AC SPD Uc and MCOV values. Solar PV and DC SPDs use Ucpv selection logic and should be reviewed separately.
