PVC, UV Resistance, and LSZH Conduit: What We Explain to New Colleagues

When new colleagues join Velkor, one question comes up often: what is the difference between ordinary PVC-coated flexible metal conduit and low-smoke, halogen-free conduit?

It is an understandable question. Both may be described as jacketed flexible metal conduit, but the jacket material and its performance requirements can be different. Then another question follows: if PVC contains chlorine, does that mean it cannot resist UV?

We also encounter low-smoke, halogen-free flexible conduit frequently in our work with Chilean customers. That experience makes these distinctions especially useful for our team. We wrote this guide for new colleagues, buyers and anyone entering the electrical-products industry who wants a clearer starting point.

Start with the metal core and the outer jacket

For the jacketed flexible metal conduits discussed here, the metal core provides mechanical protection for wiring while allowing flexible routing. The outer jacket adds a barrier against moisture and contaminants.

With PVC-coated conduit, that outer material is polyvinyl chloride. With a halogen-free jacket, a different formulation is used. The core construction, dimensions, jacket formulation and fitting arrangement still need to be compared: changing one description does not make two products identical.

This is the starting point we want new colleagues to take away: identify the construction first, then discuss the performance of the particular version.

PVC contains chlorine. Why can it still resist UV?

Chlorine is part of PVC's chemical composition. UV resistance describes how a material withstands ultraviolet exposure under specified conditions. The presence of chlorine does not, by itself, establish whether a conduit jacket passes a sunlight-resistance test.

A practical example is ANAMET's Type UA HD flexible metal conduit. Its manufacturer specifies an interlocked galvanized steel core with a UV-resistant PVC jacket. PVC and UV resistance therefore can coexist in a real product.

That does not make every PVC jacket suitable for the same outdoor exposure. For an outdoor connection, look for the actual product's sunlight-resistance information and temperature range. A halogen-free jacket also needs its own UV-performance information if it will be exposed to sunlight.

Nor should an accelerated weathering test be translated into a fixed outdoor lifetime. ANAMET's technical FAQ explains that such testing cannot precisely establish years of service in every real environment.

What does low-smoke, halogen-free actually mean?

LSZH means low smoke, zero halogen; LSHF means low smoke, halogen-free. The key is that the description combines two requirements: low smoke generation under the relevant test conditions, and the applicable halogen-content or halogen-emission requirement.

PVC contains chlorine, so a PVC jacket cannot be described as halogen-free. But a halogen-free statement alone does not establish low-smoke performance. If a specification asks for both, both must be addressed.

Manufacturers distinguish these tests in their technical documentation. For example, Electri-Flex lists smoke-generation and flammability test references separately for its low-smoke, zero-halogen conduit range. Low smoke, flame retardancy and UV resistance are not interchangeable descriptions.

For someone new to this industry, it helps to read the words one at a time: “low smoke” concerns smoke performance; “halogen-free” concerns the relevant halogen requirement; “UV-resistant” concerns exposure to ultraviolet light. None of these labels should silently stand in for another.

Why this matters in our work with Chilean customers

In our experience serving Chilean customers, low-smoke, halogen-free flexible conduit comes up frequently. When a new colleague sees this alongside ordinary PVC-coated conduit, the natural question is whether it is simply another name for the same product.

It is not just a naming difference. The jacket requirements need to be understood. If the requested product is low-smoke and halogen-free, offering a UV-resistant PVC jacket does not satisfy the halogen-free part. If a halogen-free conduit will be used outdoors, its halogen-free description does not answer the UV question.

For our team, the useful habit is to read each requirement separately and match it to the product being offered. That turns an unfamiliar label into a concrete question about the jacket and its performance.

What else can the jacket do?

Depending on its formulation, a PVC jacket can provide resistance to oils, selected chemicals and sunlight, in addition to acting as an environmental barrier. Chemical compatibility depends on the fluid involved: oil-resistant does not mean resistant to every cleaning chemical or solvent.

Liquidtight protection is another separate consideration. The jacket and compatible fittings work together as a system. A plastic outer covering alone does not establish the protection rating of an installed assembly.

For example, a connection exposed to sunlight and cleaning fluids needs both UV and chemical-compatibility considerations. If it also needs liquidtight protection, the fittings and installation conditions belong in that selection. No single jacket label answers the whole specification.

A brief look at the history

Jacketed flexible conduit has a long industrial history. ANAMET's retrospective white paper states that PVC was used for liquidtight electrical conduit jackets after 1942. Its company history separately records US production of ANACONDA SEALTITE conduit from 1949.

These are development milestones, not proof of one inventor or a universal invention date for all PVC-coated flexible conduit. A connector invention, a conduit introduction and a company's founding are different events.

What we want newcomers to remember

At Velkor, questions from new colleagues remind us how easily familiar product terms can become confusing. This article is our way of making the explanation more useful to people who are just starting out.

Start with the construction. Identify the jacket material. Then separate the required properties: UV resistance, low smoke, halogen-free composition, chemical resistance and liquidtight system protection. A product can combine several of these, but one does not automatically prove the others.

If you are comparing two flexible conduit specifications, send us the size, jacket requirements and installation environment. Those details help us discuss the actual differences. You can also explore Velkor's electrical product range.