UL 651

Please note: All interim revisions for this edition available at time of your purchase will be included.

Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings

UL 651

1 Scope

1.1 General

1.1.1 These requirements cover Schedule 40, Schedule 80, Type EB and Type A extruded rigid PVC (polyvinyl chloride) electrical conduit and fittings. These requirements also cover elbows, couplings, adapters, expansion joints, and similar fittings that are constructed of rigid PVC. The designations "Schedule 40", "Schedule 80", "Type EB", "Type A" refer to USA trade sizes of conduit having iron pipe-size outside diameters and specific wall thicknesses. Couplings, adapters, expansion joints, and similar fittings are intended to be used with Schedule 40, Schedule 80, Type EB and Type A rigid PVC conduit, elbows, in accordance with the National Electrical Code (NEC), NFPA 70.

1.1.2 Rigid PVC conduit and fittings covered in these requirements are intended for use as rigid nonmetallic raceway for wires and cables in accordance with the National Electrical Code (NEC), NFPA 70.

1.1.3 Conduit bodies (pull boxes) and covers, flush-device boxes and covers, and outlet boxes and covers that are constructed of rigid PVC or another nonmetallic material and are for use with the rigid PVC conduit and fittings covered in these requirements are covered separately in the Standard for Nonmetallic Outlet Boxes, Flush-Device Boxes, and Covers, UL 514C.

1.1.4 Rigid PVC conduit and fittings covered in these requirements are intended to be joined to each other and to rigid PVC boxes, conduit bodies, and fittings in the field by means of a cement that is or contains a solvent for polyvinyl chloride.

1.1.5 Unless the wording of a requirement that applies to rigid PVC conduit and fittings specifically limits the requirement to Schedule 40, Schedule 80, Type EB or to Type A, each such requirement in this standard applies to all types.

1.1.6 Reinforced thermosetting resin conduit and associated fittings are covered separately in the Standard for Aboveground Reinforced Thermosetting Resin Conduit (RTRC) and Fittings, UL 2515 and the Standard for Belowground Reinforced Thermosetting Resin Conduit (RTRC) and Fittings, UL 2420.

1.2 Schedule 40 and 80 conduit and fittings

1.2.1 Schedule 40 rigid PVC conduit and fittings are for aboveground use indoors or outdoors exposed to sunlight and weather, and for underground use by direct burial or encasement in concrete. Schedule 40 rigid PVC conduit, elbows, that are specifically marked for underground use are suitable for use underground only by direct burial or encasement in concrete.

1.2.2 Schedule 80 rigid PVC conduit and fittings are for use wherever Schedule 40 rigid PVC conduit may be used and are for installation on poles in accordance with the National Electrical Code (NEC), NFPA 70.

1.2.3 The following restrictions apply to use of the Schedule 40 and Schedule 80 rigid PVC conduit and fittings mentioned in 1.1.1:

a) Use at 50 C (122 F) and lower ambient temperatures and

b) Use with 75 C (167 F) wiring, but the conduit and fittings may be used with 90 C (194 F) wiring if they comply with the construction (see Conduit for Use with 90 C Wire, 6.15) and marking (see 8.2.1, 8.2.4 and 8.2.5) requirements covering use with 90 C (194 F) wiring.

1.2.4 In addition to the applicable requirements specified in this standard, Schedule 40 and Schedule 80 rigid PVC conduit intended for directional boring shall be subjected to the performance requirements in 6.12.

1.2.5 The expansion joints covered by these requirements are fittings intended to compensate for linear thermal expansion of a span of Schedule 40 and Schedule 80 rigid PVC) conduit.

1.3 Type EB and A conduit and fittings

1.3.1 The Type EB and Type A rigid PVC conduit and fittings mentioned in 1.1.1 are intended for use at 50 C (122 F) and lower ambient temperatures. Type A rigid PVC conduit and fittings are intended for use with 75 C (167 F) wiring. Type A and Type EB rigid PVC conduit and fittings, where encased in concrete in trenches outside of buildings, may be used with 90 C (194 F) wiring.

1.3.2 Type EB (encased burial) rigid PVC conduit is intended for encasement in concrete in trenches outside of buildings. Type A rigid PVC conduit is intended for encasement in concrete in any location.

1.4 Applications

1.4.1 Couplings covered by these requirements are fittings intended for joining:

a) Two lengths of rigid PVC conduit,

b) A length of rigid PVC conduit to a rigid PVC elbow and

c) In conjunction with a junction-box adapter, a length of rigid PVC conduit or a rigid PVC elbow to a box.

1.5 Fittings

1.5.1 Junction-box adapters covered by these requirements are fittings intended to connect a length of rigid PVC conduit, a PVC elbow to a rigid PVC box (not limited to junction boxes) with a coupling.

1.5.2 Internally-threaded adapters covered by these requirements are fittings intended for joining a length of rigid PVC conduit, a PVC elbow to threaded rigid metal conduit or other externally-threaded devices.

1.5.3 Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to:

a) The knockout area of a metal box with a metal locknut,

b) A threaded metal hub or fitting on a metal box,

c) A threaded hub on a phenolic box, or

d) A knockout in a phenolic box.

1.5.4 Reducers covered by these requirements are fittings intended for joining lengths of two different sizes of rigid PVC conduit.

1.5.5 Caps covered by these requirements are fittings intended for closing the ends of unused lengths of rigid PVC conduit.

1.5.6 Bell ends covered by these requirements are fittings intended to provide a bushed opening at the open end of a length of rigid PVC conduit.

1.5.7 Construction requirements for fittings covered by this standard are specified in Section 5. Performance requirements are specified in Section 7.