UL 1696-2021 pdf download – Mechanical Protection Tubing (MPT) and Fittings.
3.3 Connector – A fitting intended to terminate, secure, and support MPT to an enclosure, equipment or similar device. 3.4 Coupling – A fitting intended to securely connect two lengths of MPT. 3.5 Fitting – A device, such as a coupling or connector, that provides a means for securing MPT to an enclosure, splicing between lengths of MPT, or securing MPT to equipment that maintains the support and protection of the MPT. 3.6 Composite Fitting – A fitting constructed of both metallic, other than screws and the like, and nonmetallic materials. Note: The presence of screws, nuts, washers and unexposed metallic sleeves for screws should not be the sole means to change the classification of a fitting from “nonmetallic” to “composite.” These components generally are not likely to become energized in the event of a conductor fault so they are not subject to the test in 6.13 and a protective coating is not measured in accordance with 6.14.2. 3.7 Metallic Fitting – A fitting constructed completely of metallic materials. 3.8 Nonmetallic Fitting – A fitting constructed completely of nonmetallic materials. Note: See note in 3.6. 3.9 Mechanical Protection Tubing (MPT) – An enclosed channel of nonmetallic or composite construction that is intended to be repeatedly flexed throughout its life. 3.10 Composite MPT – A tubing constructed of nonmetallic material with a rigid metallic reinforcement. 3.11 Nonmetallic MPT – A tubing constructed completely of nonmetallic materials. 3.12 Working Temperature – The temperature to which the MPT is subjected during its intended use. 4 General Requirements 4.1 MPT covered by this Standard is intended for use as a system with particular fittings or clamps in compliance with 5.5. When intended for use with clamps, MPT may be evaluated without identified particular fittings. 4.2 MPTand associated fittings are permitted to be designated for use in wet locations or in dry locations only.
5 Construction 5.1 Nonmetallic MPT 5.1.1 Nonmetallic MPTshall be: a) A layered construction that consists of a jacket or lining, or both, that is integral to the nonmetallic flexible material, with or without a rigid nonmetallic reinforcement (core) embedded in the wall; b) A construction with internal and external surfaces, formed of a homogeneous nylon (polyamide) compound; or c) Another construction that meets the performance requirements of this Standard. 5.2 Composite MPT 5.2.1 Composite MPTshall be: a) A layered construction that consists of a jacket or lining, or both, with a metallic reinforcement; or b) Another construction that meets the performance requirements of this Standard. 5.3 Dimensions 5.3.1 The manufacturer shall provide the critical dimensions for MPT. 5.4 Internal surface 5.4.1 The internal surface of MPT and fittings shall be free from obstructions that can cause abrasion or hinder free passage of the conductors, wires and cables. 5.5 Fittings and clamps 5.5.1 A metallic fitting, nonmetallic fitting, or composite fitting for MPT shall be provided with a smooth end stop.