UL 514B Pipe, Tubing and Cable Fittings

The standard “UL 514B Pipe, tubing and cable fittings” developed by Underwriter Laboratories (UL) describes a procedure for fittings used with cables and conduits designed for installation in accordance with the “NFPA 70 National electrical code”, “CSA C22.1 Canadian electrical code, Part I Safety standard for electrical installations” and a Mexican official standard “NOM-001-SEDE Electrical installations”.

These requirements mainly cover:

Pipe locknuts, pipe bushings, metal stud bushings, pipe bodies and inlet elbows
Electrical metal conduit, flexible metal conduit, intermediate metal conduit, liquid tight flexible conduit, rigid metal conduit and fittings for service entrance headers
Fittings or box clamps and submersible fittings referenced from other standards for armoured cable, metal-clad cable, aluminium-sheathed cable, mineral-insulated cable, non-metal-sheathed cable, service-entrance cable and tray cable
Flexible cable, flexible non-metallic and metallic conduit, insulating bushes, couplings, reducing washers
Fittings for nozzles

The following are excluded from these requirements:

Fittings designed for use in hazardous locations as defined in the “NFPA 70 National electrical code”, “CSA C22.1 Canadian electrical code, Part I Safety standard for electrical installations” and “NOM-001-SEDE Electrical installations” standard.
Fittings designed for use with surface duct systems.
Pipe nipples, threaded elbows, and threaded couplings designed for use with rigid metal pipe or intermediate metal pipe.

In short, these requirements cover the fittings to be used with the conduit and outlet boxes to be used in accordance with the National Electrical Code, NFPA 70.

The general requirements in this standard are determined as follows:

The requirements apply to all fittings except those for use with rigid nonmetallic conduit. These are supplemented or replaced in subsequent sections by requirements that apply exclusively to nonthreaded fittings, wet location fittings, and concrete-tight fittings, and the like.
Any part of a fitting that may come into contact with an insulated conductor must be smooth and rounded.
A fitting that will accommodate more than one commercial duct size shall comply with this standard when each duct size is installed as intended.
A fitting, other than a fitting or locknut, internally threaded for connection to intermediate metal conduit or rigid metal conduit shall be provided with a positive end stop for the conduit and a smooth, rounded throat to prevent abrasion of the insulation on conductors entering the conduit from the fitting. The throat shall be continuous around the circumference.
A fitting for pipe connection shall have a smooth rounded inlet hole. Unless otherwise specified, the throat diameter of the inlet hole shall be within the limits specified in the table for a bushing and compatibility shall be determined by applying the limit indicators shown in the figure and having the dimensions specified in the table.
When a fitting, cable or conduit is clamped in place, it should substantially close the opening in which it is used and not allow the passage of a 4,8 mm diameter probe.
All metal parts of a fitting that can be energized must be grounded unless they are positioned so that they cannot come into contact.

In this standard, the material requirements are specified as follows:

A material designed to be installed between a fitting or fitting cover and a casing used to exclude water or moisture shall be constructed of:
- Material that complies with the requirements for use as a gasket material in accordance with the standard “UL 157 Gaskets and seals”
- An elastomer suitable for elastomeric materials testing
- Expanded (foam) closed cell material suitable for compression/set testing
A polymeric fitting must comply with flammability testing. However, a fitting or insulating bushing made of a specific material in accordance with the standard “UL 94 Flammability tests of plastic materials for parts in appliances and instruments” does not require flammability testing. Additionally, a polymeric component positioned so that it cannot spread flames from one area to another or bridge a potential ignition source to a flammable material does not require flammability testing.
A polymeric throat or throat liner installed on a metal fitting shall comply with the requirements for fittings in the flammability test. However, exceptions shall be made.
The minimum thickness of a polymeric material shall be determined by measuring the thickness of the material at any point other than the bottom of a groove used to mount a polymeric throat into a bushing. The thickness at threads shall be measured from the top of the thread to the smooth wall surface through the material.
An insulation bush must be assigned one of the temperature values specified in the table.

A ferrous metal fitting shall be protected against corrosion with a zinc cadmium coating not thinner than that specified in the table. A bar hanger consisting of a stainless steel fitting and steel bar stock need not be so protected. A sharp edge, a drilled hole and the threaded surface of a fastened hole need not be so protected. Other types of coating may be used provided they have been investigated and found acceptable for the purpose.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "UL 514B Pipe, tubing and cable fittings" standard are also provided to businesses.