PDFWAC 296-46B-501
Class I locations.
001 Sewage disposal systems.
(1) Pumping chambers for sewage, effluent, or grinder pumps in on-site and septic tank effluent pump (S.T.E.P.) disposal systems will be considered unclassified when not more than five residential units are connected to the system, residential units are connected to a utility sewage system, or when nonresidential systems have residential loading characteristics and all of the following general installations requirements are complied with:
(a) The pumping chamber must be adequately vented. Venting may be accomplished through the building or structure plumbing vents where the system venting has been approved by the local jurisdiction authority or by a direct two-inch minimum vent to the atmosphere;
(b) Equipment that in normal operation may cause an arc or spark must not be installed in any pumping chamber;
(c) Float switches installed in a pumping chamber must be hermetically sealed to prevent the entrance of gases or vapors;
(d) Junction boxes, conduits and fittings installed in the septic atmosphere must be of a noncorrosive type, installed to prevent the entrance of gases or vapors;
(e) Where a conduit system is installed between the pumping chamber and the control panel, motor disconnect, or power source, an approved sealing method must be installed to prevent the migration of gases or vapors from the pumping chamber, and must remain accessible; and
(f) Wire splices in junction boxes installed in pumping chambers must be suitable for wet locations.
(2) Residential wastewater loading characteristics in a nonresidential installation:
(a) For systems that process less than 3,500 gallons of wastewater per day may be certified by:
(i) An on-site wastewater designer licensed under chapter 18.210 RCW; or
(ii) A professional engineer, engaged in the business of on-site wastewater system design, licensed under chapter 18.43 RCW.
(b) For systems that process 3,500 gallons or more of wastewater per day may be certified by a professional engineer, engaged in the business of on-site wastewater system design, licensed under chapter 18.43 RCW.
Written documentation must be signed and stamped by the designer or engineer and provided to the electrical inspector prior to inspection.
(3) Any residential or nonresidential system that has building or structure floor drains being discharged into the system is classified as Class I Division 1. Drains from any commercially made tub, shower, basin, sink, or toilet are not considered floor drains.
(4) Pumping chamber access covers can be covered by gravel, light aggregate, or noncohesive granulated soil, and must be accessible for excavation. Access covers that are buried must have their exact location identified at the electrical panel or other prominent location by an identification plate. The authority having jurisdiction for performing electrical inspections must approve the identification plate location.
(5) Indoor grinder pumps installed in chambers with less than 50 gallons capacity are not required to meet the requirements of this section, except for the venting requirements in subsection (1)(a) of this section. Indoor grinder pumps installed in chambers with less than 50 gallons capacity are not classified systems as described in Article 500 NEC.
(6) Secondary treatment effluent pumping chambers such as sand filters are unclassified, and require no special wiring methods.
(7) Inspection approval is required prior to covering or concealing any portion of the septic electrical system, including the pump. New septic and effluent tanks containing electrical wires and equipment must be inspected and approved prior to being loaded with sewage.
(8) On-site sewage disposal systems using pumps must have audible and visual alarms designed to alert the resident of a malfunction. The alarm must be placed on a circuit independent of the pump circuit.
[Statutory Authority: Chapter 19.28 RCW, RCW 19.28.031 and 19.28.251. WSR 24-05-085, § 296-46B-501, filed 2/21/24, effective 4/1/24; WSR 19-15-117, § 296-46B-501, filed 7/23/19, effective 8/23/19. Statutory Authority: RCW 19.28.006, 19.28.010, 19.28.031, 19.28.041, 19.28.061, 19.28.101, 19.28.131, 19.28.161, 19.28.171, 19.28.191, 19.28.201, 19.28.211, 19.28.241, 19.28.251, 19.28.281, 19.28.311, 19.28.321, 19.28.400, 19.28.420, 19.28.490, 19.28.551. WSR 06-05-028, § 296-46B-501, filed 2/7/06, effective 5/1/06. Statutory Authority: RCW 19.28.006, 19.28.010, 19.28.031, 19.28.041, 19.28.061, 19.28.101, 19.28.131, 19.28.161, 19.28.171, 19.28.191, 19.28.201, 19.28.211, 19.28.241, 19.28.251, 19.28.271, 19.28.311, 19.28.321, 19.28.400, 19.28.420, 19.28.490, 19.28.551, 2002 c 249, chapters 34.05 and 19.28 RCW. WSR 03-09-111, § 296-46B-501, filed 4/22/03, effective 5/23/03.]