AC-DC Power Module

AC-DC power modules are one of the most compliance-critical components in any electronics product. Get the wrong grade from the wrong factory, and you are looking at failed certification tests, costly re-spins, or — in the EU — customs holds. This page covers what separates competent Chinese suppliers from budget-tier gambles, and where the real compliance traps are for Western buyers.

IEC 62368-1 vs IEC 60950-1: Why the Safety Standard Transition Still Catches Buyers Out

IEC 60950-1 (the old IT equipment safety standard) was withdrawn in December 2020 for new product submissions in most markets. The replacement is IEC 62368-1, a hazard-based safety engineering (HBSE) standard that covers audio/video, IT, and communications equipment under one framework.

The practical difference for power module buyers: a CB test report citing IEC 60950-1 is no longer valid for new CE or UL submissions. Yet a meaningful share of Chinese power module inventory — especially from smaller Shenzhen manufacturers running legacy tooling — still carries IEC 60950-1 certificates issued before the cutoff. They are legally grandfathered for existing products in some markets but cannot be used to certify a new product for EU or US sale.

What to check when a supplier sends you a cert package:

• CB report issue date: Any IEC 60950-1 CB report issued before December 2020 will not satisfy a new IEC 62368-1 filing. Ask for the 62368-1 test report specifically.
• UL file number verification: UL maintains a public database (iq.ulprospector.com). Paste the UL file number from the datasheet and verify the scope covers the exact model, output voltage, and wattage. It is not uncommon to find that only the 12V/60W variant is listed, but the 24V/100W variant you want is not.
• CB scheme to national mark: A CB test report is an intermediate document. It requires a national certification body to issue the actual mark (UL, CE LVD, PSE, etc.). Confirm the supplier holds the derivative mark, not just the CB report.
• Notified Body identity (CE): For LVD (Low Voltage Directive), self-declaration is permitted, but IEC 62368-1 requires a third-party test report. Ask for the lab name and accreditation number — some factories present internal test reports as if they were third-party.

Mornsun, Cincon, and MEAN WELL (headquartered in Taiwan, manufactured partly in China) maintain current IEC 62368-1 and UL 62368-1 certification portfolios across their full product ranges. Budget-tier suppliers from Shenzhen’s EPS or eStar clusters are more inconsistent — some have updated their certs, some have not.

We verify cert authenticity as part of every factory audit for power-supply suppliers. See also our power electronics sourcing overview for supplier landscape context.

Standby Power and Efficiency Regulations: EU ErP Lot 6 and US DOE Level VI

If your product is sold in the EU or US, the efficiency tier of the power module you select is a regulatory matter, not just a datasheet preference.

US DOE Level VI (10 CFR Part 430) mandates minimum efficiency at four load points — 10%, 25%, 50%, and 100% of rated output — plus a maximum no-load power draw. The thresholds vary by output power:

Output power	Min. avg. efficiency	Max. no-load power
<1W	0.5 × Pout + 0.16	0.100W
1W – 49W	0.071 × ln(Pout) + 0.67	0.100W
49W – 250W	0.880	0.210W
>250W	0.875	0.500W

ln = natural log. These are the Level VI thresholds currently in force.

EU ErP Lot 6 (Commission Regulation EU 2019/1782) applies to external power supplies. For single-output AC-DC modules used as external supplies, the standby (no-load) threshold is 0.5W, and the average active-mode efficiency requirements mirror the US Level VI numbers closely.

The compliance failure mode we see most often: a buyer specifies a module with a Level VI compliant average efficiency but forgets to check the no-load consumption figure. Some open-frame modules rated at 91% average efficiency still draw 0.8W at no load — which fails both ErP Lot 6 and DOE Level VI no-load limits.

When sourcing power modules for EU or US end products, we pull the full efficiency test report (not just the headline efficiency number) and cross-check all four load points plus no-load. This is a 10-minute step that has prevented multiple expensive compliance failures for our clients.

Leakage Current and Safety Earth: Class I vs Class II for Your Application

Touch current (formerly called leakage current) limits are where power module selection intersects directly with product safety architecture decisions.

Class I products rely on a protective earth connection. The safety standard allows a higher touch current — IEC 62368-1 allows up to 3.5mA for stationary IT equipment — because the earth provides fault current return. Class I power modules with an earth lug are typical in industrial and rack-mount gear.

Class II products use double or reinforced insulation instead of earth. The touch current limit drops to 0.25mA (IEC 62368-1 clause 5.7). This is the relevant limit for handheld devices, most consumer products, and anything where the user may not be connected to earth.

The trap: many “Class II” marked power modules from budget Chinese suppliers are tested at the module level and pass the 0.25mA limit in isolation. When integrated into a product with a larger PCB area, additional capacitive coupling to the chassis, and longer cable runs, the system-level touch current exceeds 0.25mA. IEC 62368-1 system-level testing then flags a violation even though the module’s individual cert is valid.

For medical-adjacent products (not FDA-regulated medical devices, but consumer wellness or industrial monitoring gear where the user contacts the product during operation), the relevant limits are even tighter: IEC 60601-1 specifies 100µA patient leakage for applied parts. If your product borders this space, verify the module’s construction carefully before committing to a design — output Y-capacitor values, the insulation class, and creepage distances all matter.

We flag leakage current implications during our pre-production inspection step when the integration context indicates a Class II or low-touch-current requirement.

Chinese Supplier Landscape: Tier Structure and What to Actually Check

The Chinese AC-DC power module market has three practical tiers for Western OEM buyers:

Established brands with full cert portfolios

• MEAN WELL (Taiwan, factories in China): The reference point for reliability and cert completeness. Higher priced than mainland alternatives, but UL file numbers are consistently verifiable, and their technical support is responsive in English. Lead times can stretch to 8–12 weeks for less common variants.
• Mornsun (Shenzhen): Mainland China’s strongest brand for industrial DC-DC and AC-DC modules. IEC 62368-1 and CE portfolios are current. Strong in DIN-rail and wide-temperature variants. Less familiar to US buyers but well-regarded in European industrial automation.
• Cincon (Taiwan, manufacturing in Guangdong): Solid for board-mount and open-frame variants in the 5W–75W range. CB and UL certs maintained. Pricing sits between MEAN WELL and budget tier.

Mid-tier — verify individually

Dozens of Shenzhen and Dongguan factories operate at this level. Some have legitimate IEC 62368-1 certs; others have outdated or narrowly-scoped certificates. Quality indicators worth checking:

• Does the factory have a UL Recognized Component listing (distinct from Listed, but valid for internal components)?
• Is the CB test report from an IECEE-accredited lab (SGS, TÜV, Intertek, Bureau Veritas)?
• Can they provide a production test report showing efficiency and hipot test results from the actual lot, not just the type-test sample?

Budget tier — high compliance risk

Generic Shenzhen EPS (external power supply) factories producing unlabeled or white-label modules priced 30–50% below mid-tier. Many of these modules are sold on Alibaba under rotating brand names. The common issues: IEC 60950-1 certs presented as current, UL file numbers that don’t match the product in hand, and efficiency figures taken from best-case test conditions rather than the actual average active-mode calculation.

For a product going to EU or US retail, budget-tier power modules are rarely worth the risk. The cost of failed UL or CE testing — retesting fees, redesign time, delayed market entry — exceeds the per-unit savings on any realistic volume under 50,000 units.

Our sourcing process for power modules includes cert verification, lab accreditation confirmation, and a factory qualification step before we recommend any supplier for OEM production. We also conduct pre-shipment inspections that include production sample efficiency spot-checks where a calibrated load bank is available at the factory. For new supplier relationships, our audit service covers the quality management system, production test equipment calibration records, and incoming component inspection for critical parts (primary capacitors, transformers, optocouplers).