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Subchapter 5. Electrical Safety Orders
Group 2. High-Voltage Electrical Safety Orders
Article 39. Signs and Outline Lighting--Exceeding 600 Volts (Formerly Article 88)
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§2971. Transformers.

Transformers shall comply with the following:

(a) Voltage. The transformer secondary open-circuit voltage shall not exceed 15 kilovolts with an allowance on test of 1 kilovolt additional. In end-grounded transformers the secondary, open-circuit voltage shall not exceed 7.5 kilovolts with an allowance on test of 500 volts additional.

(Title 24, Part 3, Section 600-32(a).)

(b) Type. Transformers shall be of a type approved for the purpose and shall be limited in rating to a maximum of 4.5 kilovolt-amperes.

Open core-and-coil type transformers shall be limited to 5 kilovolts with an allowance on test of 500 volts, and to indoor applications in small portable signs.

Transformers for outline lighting installations shall have secondary current ratings not in excess of 30 milliamperes.

(Title 24, Part 3, Section 600-32(b) without Exception.)

(c) Transformer Secondary Connections. The high voltage windings of transformers shall not be connected in parallel; and shall not be connected in series, except that two transformers each having one end of its high voltage winding connected to the metal enclosure shall be permitted to have their high voltage windings connected in series to form the equivalent of a midpoint-grounded transformer. The grounded ends shall be connected by insulated conductors not smaller than No. 14.

EXCEPTION: Transformers for small portable signs, show windows, and similar locations that are equipped with leads permanently attached to the secondary winding within the transformer enclosure and that do not extend more than 8 feet beyond the enclosure for attaching to the line ends of the tubing shall be permitted to have leads smaller than No. 14, but shall not be smaller than No. 18 and shall be of a type approved for the purpose.

(Title 24, Part 3, Section 600-32(d).)

(d) Accessibility. Transformers shall be accessible.

(Title 24, Part 3, Section 600-32(e).)

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code; and Section 18943(c), Health and Safety Code.


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

2. Amendment filed 12-10-87; operative 1-9-88 (Register 88, No. 1).

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