Do I need both UL and IEC?

You need the approval that matches your target market. UL 1059 for North America, IEC 60947-7-1 for most other markets. Many terminals carry both, simplifying global product design.

Why are the rated currents different?

Test conditions, conductor size, ambient temperature and grouping differ between the standards. A terminal rated 16 A under UL 1059 may rate 17.5 A or 22 A under IEC at the same conductor, or vice versa. Compare with the test conditions, not the headline number.

Does CE marking require IEC?

Yes. CE marking under the EU Low Voltage Directive relies on IEC compliance (typically IEC 60947-7-1 for terminal blocks). UL approval alone does not give CE marking.

What is the group rating in UL 1059?

Group rating describes how a terminal performs when several are loaded side by side. UL publishes group ratings that reflect the actual cabinet environment, not just single-pole laboratory values.

Can I use an IEC terminal in a UL panel?

Yes, if the terminal carries a UL approval and the rating matches the circuit. Some IEC terminals are not UL listed; in that case they cannot be installed in a UL panel without an exception or field evaluation.

Which standard should I start with?

Start with the end-product standard. If the cabinet will be UL 508A, select UL 1059 terminals. If it will be IEC 61439, select IEC 60947-7-1 terminals. A terminal with both marks gives the most flexibility.

Terminal Blocks

UL 1059 vs IEC 60947-7-1 for Terminal Blocks

August 11, 2026 6 min read

Tags:

#approval standard #CE marking #IEC 60947-7-1 #international certification #North American approval #terminal block #terminal block certification #UL 1059

UL 1059 and IEC 60947-7-1 both address terminal blocks, but an approval under one system does not automatically establish an equivalent rating under the other. The practical task is to select the correct certified product, then apply the voltage, current, conductor and installation conditions shown in its certification record and datasheet.

Quick Comparison

Parameter	IEC 60947-7-1	UL 1059
Region	International (Europe, Asia)	North America (US, Canada)
Rated voltage (typical)	Up to 1000V	300V or 600V
Current rating basis	Declared rating supported by the applicable test program	Certified rating for specified conductor and use conditions
Wire size	mm²	AWG
Torque test	Per manufacturer spec	UL-specified torque values
Short-circuit test	SCCR tested (1.5–10 kA)	SCCR tested
Loaded-pole / grouping effect	Use manufacturer application data and test conditions	Use certified rating and manufacturer application data; no universal conversion factor
Creepage/Clearance	IEC 60664-1	UL 840
Flammability	Material and product requirements depend on construction and application	Material and product requirements depend on construction and certification
Marking / documentation	Ratings and connection data are supplied as required	Ratings and conditions are shown on the product, packaging, datasheet or certification record as applicable

1. Why Two Standards Matter

If equipment is evaluated for both international and North American markets, the terminal block must be acceptable under the equipment’s certification path in each market. A component certificate is not a blanket approval for every installation; the end-product evaluator also checks the component’s ratings and conditions of acceptability.

Dual-Certified Terminals

Many terminal blocks are offered with both IEC and UL ratings. A dual-approved terminal may show values such as:

IEC rating: 16A / 500V / 2.5mm²
UL rating: 15A / 300V / 14 AWG

The lower printed value is not automatically the only design limit: each market uses its own rating and installation conditions. A global design can use a common conservative limit, or maintain market-specific ratings when the product documentation and certification support them.

2. Current Rating Differences

Cross-Section	IEC Rating (typical)	UL Rating (typical)	Difference
1.5mm² (16 AWG)	16A	10–12A	UL 20–25% lower
2.5mm² (14 AWG)	24A	15–20A	UL 17–40% lower
4mm² (12 AWG)	32A	20–25A	UL 22–38% lower
6mm² (10 AWG)	41A	30A	UL 27% lower
10mm² (8 AWG)	57A	40–50A	UL 12–30% lower

These examples illustrate why ratings should not be converted by percentage. Differences can arise from conductor designation, test setup, temperature limits, spacing, product category and the exact certification program. Use the values assigned to the selected part number.

3. Loaded Positions and Derating

Long terminal strips and multi-position PCB connectors can retain more heat than a single loaded pole. The appropriate reduction depends on the certification conditions and the manufacturer’s derating data. Do not apply a universal “UL 80% rule” to every terminal block; an 80% factor may be used in some engineering practices or curve construction, but it does not replace the part-specific record.

Design Impact

Circuit	IEC-Labeled Design Example	UL-Labeled Design Example
Required current	20A	20A
Published part rating	24A under stated IEC conditions	15A under stated UL conditions
Action	Verify loaded-pole and ambient derating	Select a higher-rated certified part or reduce circuit current

The limiting approval may require a larger terminal, larger conductor or lower circuit current. Confirm the result against the exact certification and end-product standard.

4. Creepage and Clearance

Standard	Reference	Design Approach
IEC 60947-7-1	IEC 60664-1 principles as applicable	Determine from working voltage, overvoltage category, pollution degree, material group and field conditions
UL 1059	UL spacing and construction requirements as applicable	Use the certified voltage rating, product group and installation conditions

Creepage and clearance are affected by more than nominal voltage. Pollution degree, impulse withstand, insulation material, coating, field-wiring category and end-product requirements all matter. Pitch alone cannot establish a voltage rating.

5. Global-Market Selection Checklist

Identify the end-product standard and destination markets.
Confirm the exact terminal part number appears in the relevant certification record.
Compare rated voltage, current, conductor range, conductor type, strip length and torque.
Check whether accessories, jumpers and PE terminals are covered by the same system approval.
Apply ambient and loaded-position derating from the manufacturer.
Verify creepage, clearance, insulation coordination and enclosure conditions in the end product.
Keep the certification record, datasheet revision and installation instruction in the technical file.

Common Questions

Does CE marking mean a terminal block is UL Listed?

No. CE marking and UL certification serve different regulatory and conformity-assessment purposes. Verify the North American certification mark and record for the exact part.

Is an IEC current rating valid in a UL panel?

Use the current rating and conditions recognized for the UL application. The IEC value may remain useful for another market, but it does not replace the North American certified rating.

Can one global part number have two ratings?

Yes. A dual-approved terminal may carry different IEC and UL ratings. Document both and use the applicable value for each market—or use one conservative common design limit when appropriate.

6. Documents to Confirm Before Purchase

Requirement	Evidence to Obtain
UL application	Certification record for the exact part number, including ratings and conditions of acceptability
IEC application	Applicable certificate/test documentation, datasheet and declaration supplied for the exact series
Canadian market	Relevant Canadian certification record where required
CE-marked end product	Supplier documentation needed for the equipment manufacturer’s conformity assessment
RoHS / REACH	Current material declarations tied to the purchased part number

Request Certification Documents

GSConn can provide available UL file references, IEC documentation, ratings and installation conditions for the selected series. Confirm the exact part number and document revision before releasing a global-market design.

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