State of Alaska's Policy for Commercial Sewage Lift Stations (MIPL # 3)

  Commercial sewage lift stations shall be a Class 1 Division 1 hazardous location. If the electric installation complies with the following requirements, they may become Class 1 Division 2.

  1. Venting of wet wells installed outdoors or within buildings or structures:
    • Venting of wet wells installed outdoors shall have a minimum of five air changes per hour. (Passive or Mechanical)
    • Venting of wet wells located under or within a building or structure shall have a positive venting to the exterior at a minimum of five air changes per hour.

      Buildings or structures above wet wells may become nonhazardous when proper air changes and sealoffs are provided as described below.

  2. Sealoffs shall be accessible.
    • When installing sealoffs on conduits leaving wet wells that are located not within buildings or structures, the sealoff may be located either in wet wells or not more than 18 inches from the controller. ( First fitting in either case.)
    • Sealoffs on conduits leaving wet wells installed in buildings or structures shall comply with NEC section 501-5(B)(2).
  3. Intrinsically safe circuits.
    • Intrinsically safe circuits shall be provided for all floats or control wiring.
    • Except in the controller or junction box in wet wells, intrinsically safe circuits shall be separated from wiring of all other circuits that are not intrinsically safe.
  4. Wet well pump motors.
    • Pump motors installed in wet wells do not have to meet Class 1 Division 1 standards, as long as the floats are adjusted to ensure that the pump motor is always submerged.
    • The usage of hard use rubber cord shall be allowed between the junction box within wet wells and submerged pumps.
  5. Listing and labeling.
    • All material and equipment used in the installation of a sewage lift station shall comply to Article 110-3(a) and (b).

    The State of Alaska Department of Labor requires that all new installations of sewage lift stations not installed to Class 1 Division 1 standards be approved before installation.

© 1996 Gerald Newton. All rights reserved.