Coated vs Uncoated Flexible Metal Conduit: What Changes?

Identify what the outer layer needs to do

Begin with the exposure at the cable route: dry indoor air, occasional splashes, cutting fluid, cleaning agents, rubbing contact, or outdoor weather. An outer coating changes the surface facing that exposure, but its usefulness depends on the actual polymer and construction. Request the jacket material by name and ask about compatibility with the chemicals used on site. A purchasing description that says only coated flexible conduit leaves important differences unresolved, including jacket thickness, flexibility, and the intended termination method.

Distinguish covered, liquid-resistant, and liquidtight

These descriptions should not be treated as interchangeable. ABB lists covered liquid-resistant and covered liquidtight conduit families separately, with ingress performance tied to appropriate fittings. A continuous-looking jacket is therefore only one part of the selection. The connection must seal where the conduit meets the fitting and where the fitting enters the enclosure. Ask the supplier to name the tested assembly and installation conditions. Any requested protection rating should refer to that assembly rather than an isolated coil of conduit.

Review temperature, abrasion, and fire requirements separately

Do not assume that adding a jacket improves every performance characteristic. Check the selected conduit's static and moving temperature limits, jacket abrasion behavior, and any fire or smoke requirements independently. ABB's metallic catalogue separates these attributes by construction; its uncoated options and low-fire-hazard jacket options serve different needs. For a hot route beside machinery, describe both normal temperature and occasional exposure. For rubbing contact, show where contact occurs so supports, routing changes, or an appropriate protective construction can be considered.

Compare installed cost and inspection access

Compare the price of the conduit together with fittings, seals, installation time, and replacement access. A cheaper coil may require a different connector set or more space at the enclosure. Inspect sample terminations for fit and follow the supplier's cutting and assembly instructions, particularly where the jacket forms part of the sealing arrangement. For a quotation, specify the metal, preferred jacket, environment, conduit dimensions, entry thread, and required documentation. Ask the supplier to identify any assumptions before approving the final part description.

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