This is the common CSA and UL standard for low voltage transformers. It is the first edition of CSA C22.2 No. 66.3 and the first edition of UL 5085-3. This edition of CSA C22.2 No. 66.3 supersedes the requirements of CSA C22.2 No. 66 published in 1988. This edition of UL 5085-3 supersedes the Fourth edition of UL 1585 published in 1998.
As noted in Low Voltage Transformers - Part 1: General Requirements, UL 5085-1, or CSA C22.2 No. 66.1, Low Voltage Transformers - Part 1: General Requirements, the requirements in Part 3 cover Class 2 transformers for use with Class 2 circuits in accordance with the National Electrical Code, ANSI/NFPA 70, or the Canadian Electrical Code, Part I, CSA C22.1. They are intended for connection to essentially sinusoidal supply sources.
Advisory Note: For transformers intended for use in the United States, these requirements also cover Class 3 transformers for use with Class 3 circuits in accordance with the National Electrical Code, ANSI/NFPA 70, unless otherwise specified in this standard. See Annex D for Class 3 requirements.
In addition to the items specified in Clause 1.3 of Part 1, the requirements of Part 3 do not cover:
a) Power supplies (a transformer provided with a rectifier is considered a power supply);
b) Toy transformers;
c) Cord and plug connected transformers;
d) Direct plug-in transformers;
e) Transformers intended for use in audio, radio, or television type appliances; or
f) Other special types of transformers covered in requirements for other electrical devices or appliances.
Advisory Note: The requirements of Part 3 do not cover transformers intended for use in the United States having a nominal primary rating of more than 600 V and transformers having overvoltage taps rated over 660 V.
This part is intended to be used in conjunction with Part 1. The numbering of the clauses in Part 3 corresponds to the numbered clauses in Part 1. The requirements in Part 1 apply unless modified by Part 3.
A Class 2 transformer that includes a separate current-limiting impedance such as a resistor or a positive temperature coefficient device (PTC) is covered by these requirements.
A Class 2 transformer that includes a resonance regulating circuit is covered by these requirements.
An update to this product is available.
To receive notifications when an amendment, new edition or update is available to your standard no matter how you purchased it, please register on the Standards Update Service. After registering, enter the List ID for the relevant standard. The List ID can be found in the “CSA Standards Update” section within the first few pages of the standard you’ve purchased. Once notified, you can then update your standard accordingly.
PDF Format Purchased from the CSA Store
If you have purchased or subscribed to a standard from the CSA Store in PDF format, login to your CSA OnDemandTM account to access the updated PDF.
Paper Format Purchased or Purchased from Reseller
If you have purchased a paper copy of the standard from the CSA Store or purchased a standard in paper or PDF format from one of our resellers, login to the Standards Update Service to download the updates in PDF format.
eBook Format Purchased
If you have purchased a standard in eBook format, login to the CSA Reader App to download the updated version of the standard.