This information is provided free of charge by the Department of Industrial Relations
from its web site at www.dir.ca.gov. These regulations are for the
convenience of the user and no representation or warranty is made that the information
is current or accurate. See full disclaimer at https://www.dir.ca.gov/od_pub/disclaimer.html.
Subchapter 5. Electrical Safety Orders
Group 2. High-Voltage Electrical Safety Orders
ARTICLE 20. INTERRUPTING AND ISOLATING DEVICES
(1) Continuous Current Rating. The continuous current rating of interrupter switches shall equal or exceed the maximum continuous current at the point of installation.
(2) Interrupting Rating. The current interrupting rating of interrupter switches shall equal or exceed the maximum current which the switch will be required to interrupt.
(3) Momentary Rating. The momentary rating of interrupter switches shall equal or exceed the asymmetrical short circuit current available at the switch location. The asymmetrical short circuit current shall include contributions from all connected sources of energy, such as other lines, generators, large motors, etc.
(4) Fault Closing Rating. Interrupter switches shall have a fault closing rating equal to or greater than the asymmetrical short circuit current which can occur at the switch location, unless suitable interlocks or operating procedures preclude the possibility of closing into a fault.
(5) Voltage Rating. The maximum voltage rating of interrupter switches shall equal or exceed the maximum circuit voltage.
(b) Enclosure. Circuit breaker installations located indoors shall consist of metal-enclosed units or fire-resistant cell-mounted units, or shall be installed in a room of at least 2-hour fire-resistive construction, or in a transformer vault.
(1) In locations accessible only to qualified electrical workers, open mounting of circuit breakers is permitted.
(2) A means of indicating the open and closed position of circuit breakers shall be provided.
(c) Installation Requirements. Interrupter switches shall be so installed that the center of the grip of the operating handle of the switch, when in its uppermost position, will be not more than 6 1/2 feet above the floor or working platform.
(d) Enclosures as Raceways. Switch enclosures shall not be used as raceways for conductors feeding through, or tapping off, to other switches, unless adequate space is provided for this purpose.
(e) Switching of Conductors. The switching mechanism shall be arranged to be operated from a location where the operator is not exposed to energized parts and shall be arranged to open all ungrounded conductors of the circuit simultaneously with one operation. Switches shall be arranged to be locked in the open position. Metal-enclosed switches shall be operable from outside the enclosure.
(f) Fuses. Fuses installed with interrupter switches shall comply with the requirements of Article 24.
(g) Readily and Safely Accessible. Interrupter switches, except those installed on poles or structures, shall be so located that they may be operated or maintained from a readily and safely accessible place.
(h) Identification. Interrupter switches shall have a permanent and legible nameplate including the following information: manufacturer's type or designation, continuous current rating, interrupting current rating, momentary current rating, fault closing rating, and maximum voltage rating.
(i) Stored Energy for Opening. The stored energy operator shall be permitted to be left in the uncharged position after the switch has been closed if a single movement of the operating handle charges the operator and opens the switch.
4. Amendment of subsection (b), new subsections (b)(1)-(2), repealer of subsection (f), subsection relettering and amendment of Note filed 4-1-2009; operative 4-1-2009. Submitted to OAL for printing only pursuant to Labor Code section 142.3 (Register 2009, No. 14).