IEC 62368-1 Annex J and IEC 61558-1 Annex K are two independent safety-approval paths — the difference explained in plain language, with a table of which DAH JIN wire types apply to each.
"Does this transformer need to pass 62368 or 61558?" is the most common starting point in winding wire selection. The two standards govern different product categories, and their requirements for triple insulated wire live in different annexes. This article explains both paths in plain language — and which path each DAH JIN wire type is certified for.
IEC 62368-1 Annex J — ICT and Audio/Video Equipment (Chargers, Adapters, Power Supplies)
IEC 62368-1 is the umbrella safety standard for information technology and audio/video equipment (replacing the former IEC 60950-1 and 60065). Its Annex J sets out the conditions an insulated winding wire must satisfy in order to be used as reinforced insulation. The four DAH JIN types TLW-B / TLW-BB / TLW-B7S / TLW-F have three extruded insulation layers, evaluated under VDE 40008834 per IEC 62368-1 Annex J as reinforced insulation (Reinforced / Extruded / 3 layers).
- Typical applications: phone and laptop chargers, switched-mode power supply (SMPS) transformers.
- DAH JIN coverage: TLW-B / TLW-BB / TLW-B7S / TLW-F all use a three-layer independent insulation construction and are certified under UL E236542 and VDE 40008834 (for UL, the current Product iQ registration governs).
IEC 61558-1 Annex K — Transformers, Reactors, and Power Supply Units
The IEC 61558 series governs the safety of the transformer itself. Its Annex K likewise requires three-layer insulation with layer-by-layer testing for winding wires; the Annex K evaluation under VDE 40008834 covers only TLW-B and TLW-BB, a different scope from the four types under Annex J — the two annexes are two separate tickets, and passing one does not automatically mean passing the other.
- Typical applications: general-purpose power supply units, isolating transformers, power supplies built into household appliances.
- DAH JIN coverage (important): per the scope stated on the VDE certificate, the Annex K path applies to TLW-B and TLW-BB; the VDE certification scope of TLW-F does not include 61558-1 Annex K — if your product follows the 61558 path and requires Class F thermal performance, please confirm alternatives with our sales engineering team first.
Medical Equipment: The Third Path via EN/IEC 60601-1
Patient isolation in medical electrical equipment (2×MOPP and similar) is governed by EN/IEC 60601-1. Winding wires are evaluated under its sub-clause 8.8.2 and normative Annex L (Insulated winding wires for use without interleaved insulation). The applicable DAH JIN types are TLW-BB and TLW-B7S; the actual withstand voltage and isolation level must be confirmed through the end equipment's medical verification. (IEC 60601-1 also imposes minimum thickness requirements on solid insulation — winding wire qualified via Annex L is precisely the path that exempts a design from that thickness limit, one of the keys to miniaturizing medical power supplies.)
One Table: Wire Type × Safety Path
- IEC 62368-1 Annex J: TLW-B ✅, TLW-BB ✅, TLW-B7S ✅, TLW-F ✅
- IEC 61558-1 Annex K: TLW-B ✅, TLW-BB ✅, TLW-B7S ✗, TLW-F ✗
- IEC 60601-1 Annex L: TLW-B ✗, TLW-BB ✅, TLW-B7S ✅, TLW-F ✗
- Thermal class: TLW-B / TLW-BB / TLW-B7S are Class B 130°C; TLW-F is Class F 155°C
- Available conductor size range (mm): TLW-B / TLW-BB / TLW-F 0.10–1.50; TLW-B7S (stranded) contact Sales (for the certified coverage, see the table note)
- ✅ = listed within the evaluation scope of that annex on VDE 40008834; ✗ = not within the evaluation scope of that annex
(Based on the certification scopes of UL E236542 and VDE 40008834. For design decisions, always refer to the latest certificates — our Certifications page provides direct links to the official UL database.)
Frequently Asked Questions
Does passing UL automatically mean passing IEC?
No — they are separate things. UL E236542 is a component recognition within the UL system (for the US and Canadian markets); VDE 40008834 is certified against IEC/EN standards (for the European market). DAH JIN's main wire types carry both, but the end product must still be verified against the standards applicable in its market of sale.
How are the three layers of a triple insulated wire assessed in certification?
What a certificate states is the assessment result, not how the individual layers divide the work. The verifiable fact is this: the conductor carries three extruded insulation layers, evaluated under VDE 40008834 per IEC 62368-1 Annex J as reinforced insulation (Reinforced / Extruded / 3 layers). How layer count maps onto an insulation grade is a matter of reading the standard text, so please rely on the standard itself and your own safety engineer's assessment.