A power supply safety standard is not a single document you check off before shipping. It is a decision chain: what equipment are you powering, what hazards does that equipment expose, which standard addresses those hazards, and which certification proves you meet it. Get the first link wrong and the rest of the chain breaks — boards come back from testing with failures that cost weeks of rework, or a product clears safety in one country but cannot enter another without a new certification cycle.
This guide walks that chain from end to end. The table below is the starting point most engineers actually need: a direct mapping from application to the standard that governs it.
| Application | Main Safety Standard | Typical Products |
|---|---|---|
| ICT / Telecom / AV | IEC/UL/EN 62368-1 | routers, servers, displays, set-top boxes |
| Medical electrical equipment | IEC 60601-1 | patient monitors, imaging, surgical devices |
| Household & similar appliances | IEC 60335-1 | kitchen appliances, heaters, cleaners |
| Measurement / Control / Lab | IEC 61010-1 | test instruments, bench supplies, lab equipment |
| Class 2 power units (US) | UL 1310 | low-voltage enclosed supplies, adapters |
| Lighting / LED drivers | UL 8750 + IEC 61347 | LED luminaires, drivers |
| Hazardous locations | IEC/UL 60079 | oil & gas, explosive atmospheres |
The sections that follow unpack each row — what the standard covers, how the standards ecosystem fits together, and where the common mistakes hide.
What Power Supply Safety Standards Actually Protect Against
Every power supply safety standard, regardless of which technical committee wrote it, targets the same four categories of harm: electric shock, fire, excessive temperature, and mechanical or energy-related injury. The differences between standards lie in how they set thresholds for each hazard and what construction rules they impose to keep harm below those thresholds.
Electric shock protection rests on insulation and isolation — separating hazardous live circuits from anything a person can touch. Fire protection demands that components either cannot ignite under fault conditions or that any ignition is contained within a fire enclosure. Thermal limits ensure that accessible surfaces and internal components stay below temperatures that could burn skin or degrade materials over time. Mechanical and energy hazards cover moving parts, stored energy in capacitors, and battery-related risks that have grown prominent enough to warrant dedicated clauses in the latest standard editions.
These standards also share a structural distinction that causes endless confusion: a standard defines technical requirements, a certification is the process of proving a product meets them, and a mark is the visible symbol that certification has been achieved. IEC writes standards but does not certify products. UL both writes standards and certifies to them. CE is a mark, not a standard. Holding these three concepts apart is essential for understanding the rest of this guide.
IEC, UL, EN, CE — How the Standards Ecosystem Fits Together
One of the most common questions engineers ask is whether IEC, UL, EN, and CE are interchangeable. They are not — each occupies a different layer of the compliance stack.
| Term | What it actually is | Role in one sentence |
|---|---|---|
| IEC | International standard | Defines technical requirements; does not certify products |
| UL | Standards + certification body | Publishes UL standards and tests/certifies products (US) |
| EN | European adopted standard | Takes an IEC standard and publishes it as a European Norm, with or without national deviations |
| CE | Conformity mark | A self-declaration mark affixed by the manufacturer to claim compliance — not a standard |
| CSA | Canadian standards + certification | Functions similarly to UL for the Canadian market |
| TÜV | Testing and certification body | Tests to IEC/EN standards and issues certificates |
| CB Scheme | International mutual recognition system | One CB test report can be converted into national certifications across participating countries |
The relationship works like this: IEC writes the base standard. UL adopts it as UL 62368-1, the EU adopts it as EN IEC 62368-1, and CSA adopts it as CSA 62368-1. The technical core is largely identical, but each national version may contain deviations reflecting local regulatory requirements or installation practices. A manufacturer who tests to the IEC version through the CB Scheme can then convert that test report into UL, EN, or other national certifications without fully retesting — though national deviations may require supplementary testing.
IEC writes the standard, UL and TÜV test and certify to it, EN adopts it for Europe, and CE is the conformity mark you affix to declare compliance — not a standard itself.
IEC 62368-1 — The Current Standard for ICT, Telecom & AV
IEC 62368-1 governs the safety of audio/video, information technology, and communication equipment — essentially any product with a screen, a network port, or a processor that plugs into mains power. Routers, servers, monitors, set-top boxes, and their power adapters all fall under its scope.
The current edition is IEC 62368-1:2023 (Edition 4.0), published in May 2023. It departs from the prescriptive approach of its predecessors by adopting hazard-based safety engineering (HBSE). Instead of specifying exact construction details for each product category, HBSE asks the designer to identify energy sources, classify them by severity, and install safeguards proportionate to the risk. Electrical energy is classified as ES1 (safe to touch), ES2 (may cause pain but not injury), or ES3 (capable of injury). Thermal, mechanical, and radiation sources follow a similar three-tier structure.
This shift matters because it lets the standard cover product types that did not exist when the old rules were written — USB-C Power Delivery, wireless chargers, and hybrid devices that combine computing, audio, and battery systems in ways no legacy category anticipated.
From IEC 60950-1 and 60065 to 62368-1
Before 62368-1, two separate standards covered this space: IEC 60950-1 for IT equipment and IEC 60065 for audio/video equipment. Both were formally withdrawn on December 20, 2020. New product certifications must now use IEC 62368-1. The European harmonized equivalent, EN IEC 62368-1, replaced EN 60950-1 and EN 60065 under the Low Voltage Directive on the same date.
Many resources online still reference 60950-1 as if it were the active standard. It is not. If you are starting a new design today, the base document is 62368-1:2023.
IEC 60601-1 — Why Medical Is a Different Standard
Medical electrical equipment operates under IEC 60601-1, and the gap between this standard and 62368-1 is wider than most engineers initially assume. The current consolidated edition is IEC 60601-1:2005+AMD1:2012+AMD2:2020 CSV (Edition 3.2), and it governs basic safety and essential performance for any medical device that draws power from an electrical source.
The core difference is the patient. A patient connected to electrodes, catheters, or sensors may be unconscious, anesthetized, or otherwise unable to react to an electric shock. The standard responds to this reality with two parallel protection frameworks: MOPP (Means of Patient Protection) for parts that contact the patient, and MOOP (Means of Operator Protection) for parts that only staff touch. Each can be specified at 1× (single layer of protection) or 2× (double protection, the typical requirement for patient-connected circuits).
Leakage current limits are where medical certification becomes genuinely difficult. Three distinct currents are measured: earth leakage (current flowing through the ground conductor), touch current (current a person would receive by touching the enclosure), and patient leakage (current flowing through the patient connection). Patient leakage limits are measured in microamps — orders of magnitude below what an industrial power supply would ever be tested against.
This is why a board-mount DC-DC converter with a 3 kV isolation rating is not automatically medical-grade. The Cosel MHFW series, for instance, carries explicit 2×MOOP certification to ANSI/AAMI ES60601-1 and EN 60601-1 (3rd Edition), with I/O isolation rated at AC 3,000 V and DC 4,200 V. The isolation voltage is only part of the story; the certification confirms that leakage current, creepage, and clearance all meet medical thresholds, not just industrial ones.
Standards for Appliances, Lab Equipment & Lighting
Three additional application families each have their own primary standard. They appear less frequently in power supply discussions but are equally binding when they apply.
Household appliances — IEC 60335-1. Kitchen equipment, heaters, vacuum cleaners, and similar consumer appliances fall under IEC 60335-1. The current consolidated edition is IEC 60335-1:2020+AMD1:2025 CSV (Edition 6), with Amendment 1 published in 2025. The standard focuses on accessible parts, abnormal operation conditions, flame resistance of enclosures, and mechanical stability — risks that reflect how consumers interact with appliances, often without training.
Measurement and laboratory equipment — IEC 61010-1. Test instruments, bench-top power supplies, oscilloscopes, and process control equipment follow IEC 61010-1:2010. This standard emphasizes working voltage, pollution degree, and overvoltage category as inputs to insulation requirements, concepts that connect directly to creepage and clearance calculations. It differs from 62368-1 because laboratory environments involve skilled users and different energy hazard profiles.
Class 2 power units (US) — UL 1310. UL 1310 covers Class 2 power supplies and battery chargers sold in the United States. "Class 2" refers to a specific set of output limitations (maximum 100 W, with voltage and current caps defined in the standard) intended to reduce fire and shock risk to a level where less restrictive installation rules apply. UL 1310 and IEC 62368-1 are not interchangeable: a product may need both if it is a Class 2 unit sold internationally.
Lighting — UL 8750 and IEC 61347. LED luminaires and their drivers fall outside the 62368-1 scope. UL 8750 addresses LED light sources in the US market, while IEC 61347 covers lamp control gear internationally. If your power supply drives LEDs, these are the standards that apply, not the ICT standard.
Class I, Class II, Class III — Protection Categories Explained
Safety standards classify equipment by how it protects against electric shock, not by what it does functionally. Three classes cover the vast majority of power supply applications.
| Class | Protection method | Protective earth? | Typical insulation |
|---|---|---|---|
| Class I | Basic insulation + protective earth | Yes | Basic |
| Class II | Double or reinforced insulation, no earth | No | Double / reinforced |
| Class III | Supplied at SELV (voltage itself is safe) | No | Not insulation-dependent |
Class I relies on a grounded metal enclosure — if basic insulation fails, fault current flows to earth and trips a breaker. The design burden is ensuring ground continuity through every joint and fastener. Class II achieves safety without a ground connection by doubling the insulation barrier between live parts and accessible surfaces. Most consumer adapters and medical power supplies are Class II because a severed ground wire in a hospital or a living room is a failure mode the standard refuses to tolerate. Class III sidesteps insulation entirely by operating at Safety Extra Low Voltage (SELV), where the voltage level is low enough that shock is not a credible hazard.
A frequent point of confusion: Class II in this context refers to equipment protection class, not to the "Class 2" output limitation in UL 1310. They describe different things — one is about how the device prevents shock, the other about how much power it can deliver.
Creepage and Clearance — The Dimensions Behind PCB Layout
Creepage and clearance are the two geometric distances that determine whether your insulation actually works. Clearance is the shortest distance through air between two conductive parts. Creepage is the shortest distance along the surface of an insulating material between those same parts. Standards require both to meet minimum values based on the working voltage and the environment.
Four factors drive the required distances:
- Working voltage — higher voltage demands greater separation
- Pollution degree (PD1 through PD4) — most power supplies are designed for PD2, which assumes occasional non-conductive contamination; condensation environments push toward PD3
- Overvoltage category (I through IV) — reflects transient voltage exposure, with Category II typical for plug-connected equipment
- Material CTI (Comparative Tracking Index) — determines the insulating material group, which affects creepage but not clearance
The base reference is IEC 60664-1, which provides the tables linking these variables to minimum distances. Application standards like 62368-1, 60601-1, and 61010-1 reference these tables but may impose stricter values for specific contexts. Reinforced insulation requires distances equal to twice the basic insulation value.
On a PCB, these numbers translate directly into layout decisions. Slots and routing cutouts can lengthen the creepage path without consuming board area. Conformal coating can reduce the effective pollution degree, allowing tighter spacing. And for medical applications, the 2×MOPP requirement means creepage and clearance values that dwarf their industrial counterparts — which is one reason medical-grade DC-DC modules are physically larger than equivalently rated industrial ones.
Leakage Current and Means of Patient Protection
Leakage current is the small amount of current that flows through or across insulation even when the equipment functions correctly. In industrial contexts, it is a nuisance. In medical contexts, it can be lethal, and IEC 60601-1 treats it accordingly.
Three measurements matter:
Earth leakage is the current flowing in the protective earth conductor under normal operation. Every Class I medical device must keep this below limits set in the standard — typically 500 µA for normal condition, though specific limits depend on the device classification.
Touch current measures what a person would receive by touching the enclosure. Limits are lower than earth leakage because the current path goes through the body, not through a ground wire.
Patient leakage is the current that could flow through a patient via applied parts — electrodes, sensors, fluid lines. This is the strictest limit in the standard, often measured in tens of microamps, because a connected patient may have no ability to withdraw from the source.
The protection framework divides safeguards into MOPP (patient-facing) and MOOP (operator-facing). Two means of protection (2×MOPP or 2×MOOP) is the default for most medical applications, meaning the design must tolerate a single fault in any one protective barrier without exposing the patient or operator to hazardous current.
One point worth stating explicitly: a high isolation voltage rating on a DC-DC converter does not establish medical compliance. Industrial modules routinely specify 3 kV or 4 kV isolation, but without MOPP certification and patient leakage testing, they cannot be used in patient-connected circuits. The certification, not the voltage, is what matters.
Power Supply Safety vs EMC vs Efficiency
Search results for "power supply safety standards" frequently conflate three regulatory domains that are legally and technically independent. A power supply can pass one and fail either of the others.
| Dimension | Safety | EMC | Efficiency |
|---|---|---|---|
| What it addresses | Electric shock, fire, thermal injury | Electromagnetic emissions and immunity | Energy consumption and standby power |
| Representative standards | IEC 62368-1, IEC 60601-1 | CISPR 32, FCC Part 15 | DoE Level VI, EU ErP directive |
| Associated marks | UL, CE (LVD portion) | CE (EMC portion), FCC | Energy efficiency labels (no universal mark) |
| Who tests | NRTLs (UL, TÜV, CSA) | EMC laboratories | Energy efficiency laboratories |
The FCC mark, for instance, certifies that a device complies with electromagnetic emission limits under FCC Part 15. It says nothing about whether the product is safe from electric shock or fire. CE marking covers both safety (under the Low Voltage Directive) and EMC (under the EMC Directive), but these are separate assessments with separate technical files — a manufacturer affixes one CE mark but must demonstrate compliance with both.
Efficiency regulations like the US Department of Energy's Level VI standard and the EU's ErP (Energy-related Products) directive set minimum performance thresholds for active mode and no-load power consumption. They have no bearing on whether a supply is electrically safe.
Treat these as three separate compliance tracks. A product entering the EU market needs LVD safety compliance, EMC compliance, and — if it is an external power supply — ErP efficiency compliance. Passing one does not grant the others.
Safety Marks and Global Market Access
A safety mark is the visible endpoint of a certification process. The mark you need depends on where you sell.
| Mark | Market | Nature |
|---|---|---|
| UL / ETL | United States | NRTL certification (Nationally Recognized Testing Laboratory) |
| CE | European Union | Manufacturer's declaration of conformity under LVD + EMC directives |
| TÜV | EU / global | Third-party testing and certification |
| CSA | Canada | Standards development and certification |
| ENEC | European Union | European certification mark requiring third-party testing |
| CCC / CQC | China | CCC mandatory, CQC voluntary |
| PSE | Japan | Mandatory for specified products |
| RCM | Australia / New Zealand | Regulatory compliance mark |
| KC | South Korea | Mandatory certification |
The CB Scheme, operated by the IECEE (IEC System for Conformity Assessment Schemes for Electrotechnical Equipment and Components), is the mechanism that connects these national marks. A product tested at a CB Testing Laboratory receives a CB Test Report and CB Certificate. That report can then be submitted to national certification bodies in participating countries, which issue their national marks after verifying compliance with any national deviations — differences between the IEC base standard and the local adopted version.
National deviations are the reason "tested to IEC" does not automatically mean "certified everywhere." The US version of 62368-1 (UL 62368-1) may differ from the IEC version in specific clauses. The CB report covers the IEC core; deviations require supplementary testing or documentation.
The practical takeaway: define your target markets before starting certification. Testing once through the CB Scheme and converting to multiple national marks is almost always faster and cheaper than certifying country by country from scratch.
Choosing a Compliant Power Supply
By this point the decision logic should be clear. It works as a sequence of filters, each narrowing the field of acceptable standards and certifications.
1. What is the end equipment? ├── ICT / AV / telecom → IEC/UL/EN 62368-1 ├── Medical electrical → IEC 60601-1 (2×MOPP needed?) ├── Household appliance → IEC 60335-1 ├── Measurement / lab → IEC 61010-1 ├── US Class 2 unit → UL 1310 └── LED lighting → UL 8750 / IEC 61347 2. Where will it be sold? ├── US only → UL certification ├── EU only → CE (EN version + LVD) └── Multiple countries → CB report first, then convert 3. What isolation and leakage levels? └── Determines creepage/clearance and MOPP/MOOP requirements 4. Build from scratch or specify a pre-certified module?
That last question is where most projects find their tipping point. Designing a power supply from scratch means owning the entire compliance burden — insulation distances, leakage current testing, flame ratings, and certification cycles that can add weeks or months to a launch timeline. Specifying a pre-certified board-mount module shifts that burden onto the component itself. The module's safety approval is inherited by the system, provided the system designer respects the module's installation conditions and rated parameters. For medical designs requiring 2×MOPP, and for products targeting multiple regional markets, this trade-off frequently determines whether a product ships on schedule.
Conclusion
Power supply safety compliance follows a chain that starts with your equipment type and ends with a certification mark on the label. The standards along that chain are not interchangeable — IEC 60601-1 for a medical device is a fundamentally different document from IEC 62368-1 for a router, and the certification process for each reflects that difference.
Three points are worth repeating because they cause the most project delays:
First, IEC 62368-1 has replaced IEC 60950-1 and IEC 60065. Any design starting today should reference the current standard, not the withdrawn one. Second, CE is a conformity mark, not a safety standard, and FCC certification addresses EMC — not product safety. Third, creepage, clearance, and patient leakage current are the parameters that separate a medical-grade power supply from an industrial one with identical voltage and power ratings.
Vigorcomp is an independent distributor of electronic components, sourcing board-mount power supplies and DC-DC converters from Cosel, Vicor, Murata, TI, and other leading manufacturers. We provide global procurement, real-time stock visibility, and cross-reference support for allocation-constrained and certified power supply requirements. Contact us to discuss your compliant power supply sourcing needs.