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Issue 7 (Fall, 2003)  
New Safety Standard for Information Technology Equipment
CSA C22.2 No. 60950-1/UL 60950-1, First Edition

On April 1, 2003, Underwriters Laboratories Inc. Published CSA C22.2 No. 60950-1/UL 60950-1, First Edition, Standard for Safety of Information Technology Equipment (ITE).


CSA C22.2 No. 60950-1/UL60950-1 is a U.S.-Canadian Bi-national standard and is harmonized with IEC 60950-1, First Edition, which was published in October 2001. Approved by both the American National Standards Institute and the Standards Council of Canada, it is available immediately for use within the IECEE CB Scheme.

Effective April 1, 2003, all ITE products submitted to UL for UL or C-UL certification are evaluated to the new standard, unless the manufacturer formally requests CSA/UL 60950 3rd Edition.   After April 1, 2005, CSA/UL 60950-1 will apply.

This article discusses changes made to UL 60950-1 1st Edition from its predecessor, UL 60950 3rd Edition.

Multi-part Structure

IEC/UL60950-1 is a Part 1 standard of a new multi-part standard structure.   To cover the wide variety of constructions, technologies and features associated with ITE, IEC TC108 (formerly TC74), the technical committee responsible for IEC 60950-1, has adopted a Part 1/Part 2 structure for the Standard.   Part 1 provides general requirements commonly applied to ITE while Part 2 provides additional requirements for specific constructions.

Planned Part 2 standards are:

Part 21: Remote power feeding -- IEC 60950-21 was published in December 2002.   UL has proposed its UL 60950-21 version in the UL Bulletin, Subject 60950-21, dated May 9, 2003.
Part 22: Equipment installed outdoors
Part 23: Large IT equipment with integral robotics

Four Main Areas of Change

1) DC Mains Supply:

Previous versions of the standard included some requirements for batteries but the new standard provides a new definition of the term “DC Mains Supply" and includes requirements for products powered by the DC Mains Supply such as those often used in telecommunication infrastructure facilities.  

Here are sub-clauses that contain the new requirements:

New definition of the term "DC Mains Supply."

1.4.5 Specifies supply voltage tolerance as +20%, -15%, unless otherwise specified by the manufacturer. (formerly 3.6)

A rewrite of the North American Deviation for Centralized DC Power System.

Marking for terminals for connection to DC Main. Capacitance Discharge requirement revised to address DC Mains-powered products. Earthing requirement revised to address DC Mains-powered products.

Requirements for connection of wiring to DC Mains.

Requirements for DC power cord.


Touch Current requirements revised to include consideration of touch current from telecommunication network connections of DC Mains-powered equipment (but excludes touch current due to mains circuits).

2) Acoustic Test:

Sub-clause 6.5, a North American D2 Deviation, contains limits and test requirements for products with acoustic outputs.   The previous versions of UL 60950 specified test method that adequately addressed analog telecommunications but not digital.   The test methodology was changed to reference IEEE 269, Standard Methods for Measuring Transmission Performance of Analog and Digital Telephone Sets.   The actual limits for measured acoustic pressure remain the same.

3) Cable Distribution System:

IEC/UL 60950-1 contains a new Clause 7 for products intended to be connected to Cable Distribution System, such as the CATV network or an outdoor antenna.   The rationale for special requirements for ITE connected to the Cable Distribution System is that the cable/wiring is routed outside the building (outside plant) and therefore may be subjected to higher transient levels at a greater frequency than wiring routed exclusively inside the building.   See the figure for an example of product/system installed to a Cable Distribution System in the context of IEC/UL 60950-1.

UL notes that although Clause 7 is brand new, the requirements have been applied for some time in some form because they are based in part on the principles in IEC 60065 (audio-video products), and UL has had an awareness of the requirements being developed by IEC TC 108.

Here is a list of the new requirements:

New definition of the term Cable Distribution System.


Circuits connected to Cable Distribution System treated as TNV-1, TNV-3 or Hazardous Voltage according to circuit characteristics.


Separation requirements same as those for TNV circuit (i.e., sub-clause 6.2).


Either a Voltage Surge or Impulse Test is applied between Cable Distribution System and the Primary circuit

4) Battery Packs (DC National Differences):

Annex P.1 (4.3.8) of UL 60950-1 contains a new U.S/Canadian national requirement for secondary (rechargeable) battery packs intended for use in Transportable Equipment, such as those used with laptop computers.   Applicable battery packs shall comply with UL 2054, Household and Commercial Batteries.   This is a more onerous requirement than before and is based on a proposal of the Information Technology Industry (ITI) Council's TC2 on Product Safety.

Other Changes

Other changes to the standard have only limited impact on most ITE manufacturers.   They include:

1.1 Scope: Telecommunication infrastructure equipment has been formally included in the Scope of the standard.
1.2.12 Most of the flammability test methods in Annex A were replaced with references to the same test methods in the appropriate IEC flammability standard.   End product enclosure flame tests (A1, A2) and flaming oil test remain in Annex A.
1.4.12 Temperature dependent and non-temperature dependent equipment are now individually defined.   Also, all thermal criteria in the Standard have been changed from temperature rise (£GT) to maximum temperature (Tmax ).
1.4.14 A D1 National Difference clarifies that all abnormal operation tests on Pluggable Equipment Type A are to be conducted on supply source provided with 20 A branch protection. The Standard now explicitly states that Hazardous Energy Levels are measured after 60 seconds.
2.4.2 For Limited Current Circuit measurements, the Annex D touch current measurement instrument is now permitted as an alternative to a 2 k ohm non-inductive resistor to better accommodate complex waveforms.
3.1.9 As a D3 relaxation in the U.S./Canada, wire wrapping for terminal connections may be used in SELV or TNV circuit if they comply with the 2.5 N steady force test of sub-clause 4.2.2 (both are D3 Deviations)
4.3.13 Radiation: New requirements for ultraviolet (UV) are provided in (for materials) and (for human exposure). The clause also clarifies application of requirements for laser radiation .
Annex P.1 (3.2.5) Clarifies that the protective earthing lead in a Listed Power Supply Cord certified to UL817 may be solid green without yellow stripe. (DC National Difference)
Annex P.1 (4.3.5) Current Interruption requirements per UL 1977 are to be applied to connectors in non-LPS circuits that are disconnected under load (e.g., hot-swap applications). (DC National Difference )
Annex NAE (2.7.1) Clarifies that receptacles rated 15 A (NEMA 5-15R) may be protected by 20 A circuit breakers if located in non-operator accessible areas. (D1 National Difference )

For a complete UL 60950-1 Certification Impact Analysis, refer to the ITE news section of UL's website: www.ul.com/ite/ .   Also feel free to contact a UL ITE professional at the UL Office near you.

To purchase the Standard, visit www.comm-2000.com.   UL recommends that manufacturers order UL's Subscription Service for UL 60950-1 so as to automatically receive all proposal bulletins and standard revisions for a period of three years.

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