460.1 Scope. This article covers the installation of capacitors on electrical circuits.
Surge capacitors or capacitors included as a component part of other apparatus and conforming with the requirements of such apparatus are excluded from these requirements.
This article also covers the installation of capacitors in hazardous (classified) locations as modified by Articles 501 through 503.
460.2 Enclosing and Guarding.
(A) Containing More Than 11 L (3 gal) of Flammable Liquid. Capacitors containing more than 11 L (3 gal) of flammable liquid shall be enclosed in vaults or outdoor fenced enclosures complying with Article 110, Part III. This limit shall apply to any single unit in an installation of capacitors.
(B) Accidental Contact. Where capacitors are accessible to unauthorized and unqualified persons, they shall be enclosed, located, or guarded so that persons cannot come into accidental contact or bring conducting materials into accidental contact with exposed energized parts, terminals, or buses associated with them. However, no additional guarding is required for enclosures accessible only to authorized and qualified persons.
I. 600 Volts, Nominal, and Under
460.6 Discharge of Stored Energy. Capacitors shall be provided with a means of discharging stored energy.
(A) Time of Discharge. The residual voltage of a capaci- tor shall be reduced to 50 volts, nominal, or less within
1 minute after the capacitor is disconnected from the source of supply.
(B) Means of Discharge. The discharge circuit shall be either permanently connected to the terminals of the capacitor or capacitor bank or provided with automatic means of connecting it to the terminals of the capacitor bank on removal of voltage from the line. Manual means of switching or connecting the discharge circuit shall not be used.
460.8 Conductors.
(A) Ampacity. The ampacity of capacitor circuit conduc- tors shall not be less than 135 percent of the rated current of the capacitor. The ampacity of conductors
that connect a capacitor to the terminals of a motor or to motor circuit conductors shall not be less than one- third the ampacity of the motor circuit conductors and in no case less than 135 percent of the rated current of the capacitor.
(B) Overcurrent Protection. An overcurrent device shall be provided in each ungrounded conductor for each capacitor bank. The rating or setting of the overcurrent device shall be as low as practicable.
Exception: A separate overcurrent device shall not be required for a capacitor connected on the load side of a motor overload protective device.
(C) Disconnecting Means. A disconnecting means shall be provided in each ungrounded conductor for each capacitor bank and shall meet the following requirements:
(1) The disconnecting means shall open all ungrounded conductors simultaneously.
(2) The disconnecting means shall be permitted to disconnect the capacitor from the line as a regular operating procedure.
(3) The rating of the disconnecting means shall not be less than 135 percent of the rated current of the capacitor.
Exception: A separate disconnecting means shall not be required where a capacitor is connected on the load side of a motor controller.
460.9 Rating or Setting of Motor Overload Device.
Where a