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Subchapter 5. Electrical Safety Orders
Group 1. Low-Voltage Electrical Safety Orders
Article 57. Transformers and Transformer Vaults (Including Secondary Ties)

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§2533.1. Scope.

This Article covers the installation of all transformers.

Exception: No: 1: Current transformers.

Exception: No: 2: Dry-type transformers that constitute a component part of other apparatus and comply with the requirements for such apparatus.

Exception: No: 3: Transformers which are an integral part of an X-ray, high-frequency, or electrostatic-coating apparatus.

Exception: No: 4: Transformers for sign and outline lighting that comply with Article 73.

Exception: No: 5: Transformers for electric-discharge lighting that comply with Article 51.

Exception: No: 6: Transformers used for power limited fire protective signaling circuits.

Exception: No: 7: Transformers used with Class 2 and Class 3 circuits.

Exception: No: 8: Liquid-filled or dry-type transformers used for research, development, or testing, where effective arrangements are provided to safeguard unqualified persons from contacting high-voltage terminals or energized conductors.

This Article also covers the installation of transformers in hazardous locations as modified by Article 59.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Editorial correction filed 11-2-83 (Register 83, No. 45).

2. Editorial correction filed 11-3-83 (Register 83, No. 45).

3. Amendment filed 8-27-86; effective thirtieth day thereafter (Register 86, No. 37).

4. Amendment of section and Note filed 5-5-2008; operative 5-5-2008. Submitted to OAL for printing only pursuant to Labor Code 142.3(a)(3) (Register 2008, No. 19).

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