Potential material an labor savings for Supervised Industrial Installations on devices over 800 amperes


Supervised Industrial Installations: The industrial portions of a facility where all of the following conditions are met

  1. Conditions of maintenance and engineering supervision ensure that only qualified persons monitor and service the system.
  2. The premises wiring system has 2500 kVA or greater of load used in industrial process (es), manufacturing activities, or both, as calculated in accordance with Article 220.
  3. The premises has at least one service or feeder that is more than 150 volts to ground and more than 300 volts phase-to-phase

The Code: Section 240.91 (B) Supervised Industrial Installations

(B) Devices Rated over 800 Amperes

Where the overcurrent device is rated over 800 amperes, the ampacity of the conductors it protects shall be equal to or greater than 95% of the rating of the overcurrent device specified in 240.6 in accordance with (B) (1) and (2).

  1. The conductors are protected within recognized time vs current limits for short-circuit currents
  2. All equipment in which the conductors terminate is listed and marked for the application


An example of how this code applies to a circuit