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Standards and approvals in cable protection

clock 5 minutes | 25 Oct 2019

Women working with cabling in a factory

Standards and approvals are designed to ensure the safety of people and property. You won’t find much guidance online, however, as standards are protected by copyright law. They are available for purchase from the organisation who created them. Our purpose here is to give you a general overview, especially as to how some of these pertain to Essentra Components’ solutions.

In North America, wire types and practices are commonly defined by standards or approvals issued by the bodies below. You can go directly to the standard or approval now by clicking on the name.

  • UL
    Formerly known as Underwriters Laboratories, UL is a U.S. safety certification company with offices and testing facilities worldwide, and approved by the U.S. federal agency Occupational Safety and Health Administration (OSHA) to carry out performance testing.
  • “The backwards RU”
    This is how many engineers refer to the logo that labels a product as a UL Recognised Component. It indicates that the product is not equal to the UL standard, but is intended to be part of a UL product.
  • ASTM
    Formerly called the American Society for Testing and Materials, ASTM is based in the U.S. but is an international standards organisation. Over 12,000 ASTM standards are used around the world, ranging from toys to cable management.
  • MIL and MS
    MIL denotes U.S. military standards. These are used to encourage commonality and compatibility with logistics systems, and similar defense-related applications. Industry has adopted some of these standards, which is mandatory in order to procure a government contract. MS denotes U.S. military specifications.
  • UL

    UL224 is a standard that specifies the requirements for insulating tubing that typically has a round cross-section. It consists entirely of extruded compounds whose characteristic constituents are:

    • Thermosetting
    • Elastomeric
    • Thermoplastic polymers

    These requirements also cover heat-shrinkable and crosslinked tubing. Regarding application, UL224 tubing is intended for use as part of the internal wiring of electrical devices and appliances. It may be used for:

    • Insulating one or more inadequately insulated conductors
    • Bus bars
    • Motor leads
    • Transformer leads
    • Terminal lugs
    • Small assemblies of electronic components

    UL224 tubing is not supposed to be used if it will come into contact with sharp edges, corners, or projections, or where it will be subject to tension, compression, or repeated flexing. Nor is it intended for use where it’s possible to use a standard insulated conductor intended specifically for that purpose.

    Heat shrink tubing is often listed as UL224 Approval: 125°C VW-1 600V (E204071). The VW-1 is important. It indicates that the heat shrink tubing material is not likely to contribute to a fire by supporting a flame for an extended time. (Note, the flame retardancy of a cable protection sleeve is often defined as having the ability to stop burning once the source of heat is removed.)

Electrician testing electric cabling in control panel

UL 94

This is a flammability standard for plastics. You’ll see it on solutions such as nylon split cable conduit.

Usually, UL 94 is followed by V-0, V-1, or V-2. The testing procedure is as follows:

  1. 2 sets of 10 specimens are tested for each thickness.
  2. After conditioning for 48 hours at 73.4˚F (23˚C) and 50% RH, 5 specimens of each thickness are tested.
  3. 5 specimens of each thickness are tested after conditioning for 7 days at 158˚F (70˚C).
  4. Next, each specimen is mounted with long axis vertical.
  5. Each specimen is then supported so that it’s positioned 10 mm above a Bunsen burner tube.
  6. The testers apply a blue 20 mm high flame to the middle of the lower edge of the sample for 10 seconds. If, within 30 seconds, the burning stops the testers reapply the flame for 10 more seconds.
  7. If the sample drips, particles are allowed to fall 300 mm onto a layer of dry absorbent surgical cotton placed below.

V-0, V-1, V-2 share some of these standards:

All After each test flame is applied, the samples cannot burn with flaming combustion for more than 10 seconds.
V-0 The total flaming combustion time may not exceed 50 seconds for the 10 flame applications for each set of 5 samples.
V-1
V-2
The total flaming combustion time may not exceed 250 seconds for the 10 flame applications for each set of 5 samples.
All The samples may not burn with either flaming or glowing combustion up to the holding clamp.


Here’s where each differs:

V-0 The specimens cannot drip flaming particles that ignite the dry absorbent surgical cotton, nor can they have glowing combustion that lasts for more than 30 seconds after the second removal of the test flame.
V-1 The specimens cannot drip flaming particles that ignite the dry absorbent surgical cotton, nor can they have glowing combustion that lasts for more than 60 seconds after the second removal of the test flame.
V-2 The specimens can drip flaming particles that ignite the dry absorbent surgical cotton, and can have glowing combustion that lasts for more than 60 seconds after the second removal of the test flame.


Examples of solutions that meet these standards:

UL94 V-0 Cable management duct
Designed to route single coax or computer cable
Cable management duct
UV94 V-1 Cable management clips, single wire
Used in consumer appliances, HVACs, automotive and other vehicle applications
Cable management clips
UL94 V-2 Wire cable clamp
Also called a wire harness clip. Can be removed for wiring changes or replacements
Wire cable clamp


UL Recognised Component

Let’s call it UR, or the Recognised Component mark. They are not a final product, ready for installation in the field, but will go into another device. It’s that device that will bear the UL mark.

For example, Essentra’s screw mount cable tie has a flammability standard of UL94 V-2, while the overall product is a Recognised Component. This tells you that it’s intended to be used inside a UL-standard product. Industrial generator parts and HVAC components rely on particular cable ties, and that’s what this cable tie is ideal for.

UL Recognized Component
Close up of the structure of a cable

You can find cable management solutions with the Recognised Component mark by downloading Essentra’s catalogue here. Examples of components with this mark include:

Push-in Arrowhead cable tie mount
Fibre cable installation, electronics, and electrical installations in limited spaces
Push-in Arrowhead cable tie mount
Wire harness protective sleeve, slit
High flexibility for use in automation; prevents cable from pinching or kinking during use
Wire harness protective sleeve, slit
Adhesive cable tie mounts
High flexibility for use in automation; prevents cable from pinching or kinking during use
Adhesive cable tie mounts


ASTM

ASTM D4066 refers to nylon materials suitable for injection moulding and extrusion and is approved by the U.S. Department of Defense. The materials must meet the standard’s demands for density, tensile strength, impact resistance and deflection temperature.

MIL and MS

MIL-M-20693 also addresses material, specifically rigid nylon moulding plastic to be used for general-purpose, weather-resistant, and dielectric applications.

MS25281 is also a military standard, but it’s concerned with hardware specification, including those of cable clamps. Made of heat-stabilised nylon, Essentra offers a screw mount cable clamp. This cable clamp installation is intended for heavy-duty applications. It meets MS25281 specification – as well as ASTM D4066 and MIL-M-20693 standards. The clamp bears the MS part number, which is shown below. You can download the technical drawing for a closer examination here.

Cable Clamp Technical Drawing

Another military standard is MIL-S-23190E, which is concerned with plastic and metal components, and devices whose applications are tying and supporting:

  • Cables
  • Cable assemblies
  • Wires in electrical, electronic and communication equipment and interconnection systems

MS-3367 lays out specifications for cable ties. Screw mount locking cable ties are nylon cable ties. More than that, they’re heavy duty cable ties, manufactured to MS-3367 specifications and MIL-S-23190E standards. They’re used for heavy-duty applications, such as in equipment manufacturing.

Screw mount nylon locking cable tie:

Screw mount nylon locking cable tie

Download free CADs and try before you buy

Optimise your design by downloading free CADS of the solutions you’re interested in.

You can also request free specimens to ensure the cable management solutions you’ve chosen are exactly what you need. If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.

Request your free samples or download free CADs now.

Cable Management - The Design Engineers Application Guide