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Subchapter 5. Electrical Safety Orders
Group 1. Low-Voltage Electrical Safety Orders
Article 59. Hazardous (Classified) Locations

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§2540.10. Wastewater Wells.

(a) Definition.

(1) Sewage Wastewater Well (wet or dry types): A physical structure, usually underground, the prime function of which is to lift wastewater.

(2) Sewage Drywell: A sewage well which does not incorporate a reservoir in addition to the pump(s).

(3) Sewage Wetwell: A sewage well which incorporates a reservoir in addition to the pump(s).

(Title 24, Part 3, Section 3-512-9.)

(b) Hazardous Locations. Sewage wells, and the surrounding enclosure shall be classified in accordance with Section 2540.1 and the following:

(1) Sewage Dry Well. The interior of sewage dry wells shall be classified as a Class I, Division 2 location.

EXCEPTION: A sewage dry well shall be permitted to be unclassified provided the following conditions are met:

(A) The well and the surrounding enclosure is treated in accordance with the provisions of the General Industry Safety Orders, Article 108, as a potential confined space; and

(B) The well and surrounding area are provided with a suitable, continuously operating ventilation system to maintain the flammability of the interior atmosphere below 20% of the lower explosive limit (LEL). The air for the ventilation systems shall be supplied from a non-hazardous source. Means shall be provided to automatically de-energize all electrical sources of ignition in the well in the event of ventilation system failure, which would result in the interior atmosphere of the well reading 20% of the lower explosive limit (LEL).

(2) Sewage Wet Well. The interior of sewage wet wells shall be classified as a Class I, Division 1, location.

EXCEPTION: No. 1: A sewage wet well shall be permitted to be classified as Class I, Division 2, location provided the following conditions are met:

(A) The well and surrounding area are treated in accordance with the provisions of the General Industry Safety Orders, Article 108, as a potential confined space; and

(B) The well and surrounding area are provided with a suitable, continuously operating ventilation system to maintain the flammability of the interior atmosphere below 20% of the lower explosive limit (LEL). The air for the ventilation system shall be supplied from a non-hazardous source. Means shall be provided to automatically de-energize all electrical sources of ignition in the well in the event of ventilation system failure, which would result in the interior atmosphere of the well reaching 20% of the lower explosive limit (LEL).

EXCEPTION: No. 2: A sewage wet well shall be permitted to be classified as a Class I, Division 2, location provided the following conditions are met:

(A) The well and surrounding area are treated in accordance with the provisions of the General Industry Safety Orders, Article 108, as a confined space, and

(B) The pump motor(s) is completely submerged in the water whenever the motor is running, and

(C) The motor controller(s) is identified for use in a Class I location or is located outside the classified location, and

(D) The sensors-transducers are identified as intrinsically safe or for use in a Class I location.

(Title 24, Part 3, Section 3-521-10.)

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.

HISTORY

1. New section filed 8-11-83; effective thirtieth day thereafter (Register 83, No. 45).

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