Resources · Technical FAQ
Technical FAQ
Straight answers to the questions specifiers, inspectors, OEM certification engineers and distributors ask us most about Sealproof® liquid-tight conduit, tubing and connectors — including the ratings and documents that do not exist for this class of product, so you can close out a submittal without waiting on an email.
Listings & documentation
What our UL, CSA and IAPMO listings cover, and the documents we can and cannot issue.
What is the UL 94 flame rating of the liquid-tight conduit, and can you send a UL 94 certificate?
Our conduit and its compound comply with UL 94V-0; the flame test in the UL 1660 listing (UL 1696 for extra-flexible tubing) is equivalent to 94V-0. UL 94 is a material test, not a product listing, so we do not hold a separate UL 94 certificate and will not create one implying certification we do not have. We can send the spec sheet stating 94V-0 and the UL listing, verifiable in UL Product iQ. 94V-0 is not a fire-resistance rating.
Does the liquid-tight conduit carry an FT1, FT4 or FT6 rating?
No — and neither does any manufacturer's. FT ratings are flame-propagation ratings for wire and cable (FT4 is a cable-tray rating), so no FT designation exists for non-metallic liquid-tight conduit and none appears on our spec sheets, print legend or labels. Our conduit is flame tested under UL 1660 / CSA C22.2 No. 227.2.1, which is equivalent to FT1 or UL 94V-0. No LFNC-B conduit carries an FT4 or FT6 rating.
Is the liquid-tight conduit or ENT plenum rated?
No. PVC non-metallic liquid-tight conduit is not plenum rated, and PVC of this type cannot be. ENT is not plenum rated either — ours or any other manufacturer's. We have no flame-spread / smoke-developed (25/50) data of the kind used to qualify products for a return-air plenum; our flame testing is the vertical flame test under UL 1660 / CSA C22.2 No. 227.2.1 with UL 94V-0 equivalence. If you need plenum-rated product, send us the specification.
What is the NEMA 4X or IP rating of the conduit and connectors?
None. NEMA 4X and IP are enclosure ratings (UL 50, UL 508); conduit and fittings are covered by UL 1660 and UL 514B, and essentially no non-metallic conduit or fitting in the industry carries one. We have no NEMA 4X or IP certificates and do not issue letters certifying such a rating. The liquidtight, spray, outdoor and aging tests under UL 514B and UL 1660 are comparable, and NMLT-B conduit and fittings may be used with NEMA 4X enclosures without lowering either rating.
Your UL file is US-only — what covers the conduit and fittings in Canada?
For Canada the conduit is certified by CSA under file 084705 to the harmonized binational standard CSA C22.2 No. 227.2 / UL 1660. The fittings are Listed cULus and separately CSA certified under file LL-84705. For a Canadian submittal: conduit certified to CSA file 084705 and UL 1660 file E129973; fittings UL 514B file E197675 (CCN DWTT), CSA LL-84705, cULus. Acceptance under the Canadian Electrical Code is the inspector's determination based on those marks.
Is the conduit approved for direct burial in Canada as well as the US?
Yes. The conduit is UL listed for direct burial and concrete encasement, and because UL 1660 and CSA C22.2 No. 227.2 are a harmonized binational standard, the same direct-burial requirements (Clause 5.16, direct-burial stiffness by ASTM D2412) are met under the CSA certification, file 084705. Older print legends read DIRECT BURIAL IN US; current product is marked for direct burial. Acceptance on a given job remains the inspector's determination based on the certification marks.
Why do some conduits say OUTDOOR and others SUNLIGHT RESISTANT or SR?
There is no difference in the product. For LFNC-B to be LFNC-B it must be sunlight resistant and suitable for outdoor use, so all our UL-listed conduit is; our current legends carry both OUTDOOR and SUNLIGHT RESISTANT. "Outdoor" was once accepted as covering sunlight resistance; CSA then required SR / Sun Res / Sunlight Resistant and UL later harmonized. Older conduit may not show SR. Sunlight resistance is qualified by the UL 1660 weather-resistance test, not by the wording.
Can you provide a PE-stamped letter or drawing, or native CAD files for the fittings?
No to both. We do not have an engineer on staff to stamp drawings or letters; if an AHJ insists on a PE stamp, it must come from the engineer of record for the installation, not the manufacturer of a listed component. We do not have native CAD files. What we supply: PDF dimensional spec sheets and part drawings for any current item, cut sheets, compliance letters, UL project documentation and the UL listing itself.
Are you ISO certified, and what third-party certificates can you share?
We are not ISO 9001 registered and cannot supply an ISO certificate. What exists and can be shared: the UL and CSA listings (verifiable in UL Product iQ by file — E129973 conduit, E129972 extra-flexible tubing, E197675 fittings, E492410 whips), the CSA certificate, the IAPMO certificate for hose, our spec sheets, certificates of compliance and signed compliance statements. What does not exist: a standalone UL 94 certificate, NEMA/IP certificates, medical-device or potable-water certifications, or a library of independent laboratory reports.
What sizes of liquid-tight conduit do you make?
Standard sizes are 3/8" through 2" trade size (part numbers 8430–8436), stocked in coils and reels in gray, with black available. 2-1/2", 3", 3-1/2" and 4" (9437–9440) are made to order as special-order items in the 105°C compound — ask us for lead time and minimum run. A 105°C dry high-temperature version of the standard sizes (9430–9436) is also made to order.
Do you sell a non-UL (unlisted) version of the liquid-tight conduit, or metallic liquid-tight conduit?
No. We do not maintain a separate unlisted version of the liquid-tight line; every size ships as the UL/CSA listed product, and when asked to quote non-UL conduit for export we quote the standard listed product. We also do not manufacture metallic liquid-tight flexible conduit — we make non-metallic liquid-tight conduit and tubing, ENT, fittings and assemblies, and we assemble metal whips, which are listed under UL file E492410.
What is the expected service life or shelf life of the conduit and connectors?
We do not publish an expected service life or life-cycle rating for the conduit or connectors, and there is no documented shelf life. That is deliberate: real service life depends on installation method and torque, ambient and operating temperature, chemical and moisture exposure, direct UV, vibration and duty cycle, so any figure we put in writing would be misleading once applied to a specific installation. The fittings carry no expiration date and are designed for any weather, including direct sunlight.
Ratings & installation
Temperature, UV, bend radius, crush, torque, code questions and field problems.
What are the temperature ratings of the liquid-tight conduit, and which applies when it is buried or in concrete?
Standard conduit is rated 80°C dry / 60°C wet / 70°C oil resistant (marked 80C DRY 60C WET 70C OIL RES); minimum operating temperature is −18°C. A 105°C (221°F) dry version and a 90°C wet rating are available on request; we do not re-rate the standard product. The conduit is listed for wet locations, direct burial and concrete encasement, but a concrete slab is a wet location under the NEC, so the wet rating governs there — 60°C on standard product.
If the conduit is rated 60°C wet, must I use 60°C conductors?
No. Conductors rated higher than the conduit's listed temperature may be installed provided they are not operated above the conduit's rating — the principle stated in NEC 352.10(I) for PVC conduit, which UL pointed us to for this question. In practice, higher-rated conductors are acceptable when de-rated so the operating temperature does not exceed the conduit's listed rating. Verify against the NEC edition enforced in your jurisdiction.
What is the temperature rating of the non-metallic connectors, and can they be used with 105°C conduit?
The connector bodies and nuts are nylon 6 with a UL 94V-2 flammability classification and a 125°C thermal index; that thermal index is the temperature figure we can state — the fittings do not carry a separate 80°C or 90°C conduit-style rating, and we hold no separate 90°C listing for the fittings or the conduit. For high-temperature applications, including 105°C conduit, we recommend the nylon connectors because of the higher thermal index.
What is the UV rating of the conduit?
There is no numeric UV or sunlight-resistance rating, and we will not supply one. UL 1660 / CSA C22.2 No. 227.2 establishes a pass/fail test, not a grade: Clause 5.12, 1000 hours of xenon-arc exposure (ASTM G155) with water spray, then conditioning at −18°C and winding around a mandrel without cracking. All our UL-listed conduit is sunlight resistant on that basis; our UL certification page is the confirmation document. Extra-flexible tubing is tested under UL 1696 Clause 5.7.
My conduit has faded in the sun — is that a defect?
Colour fading in sunlight is not a failure of the sunlight-resistance rating and does not represent a reduction in performance. "Sunlight resistant" means resistant, not sun-proof — the same distinction as water resistant versus waterproof — and colours in any material fade over years; grey conduit fades too. If fading is accompanied by cracking, embrittlement or loss of liquidtight integrity, that is a different matter: send samples and the date code and we will investigate it as a performance complaint.
Can you provide crush, deflection or tensile-strength values for a given size?
We do not publish a tensile-strength figure or a collapse/deflection load per size. "Crush resistant" means the conduit meets UL 1660 Clause 5.5 (Resistance to Deflection) and Clause 5.16 (Direct Burial Stiffness), tested by parallel-plate loading per ASTM D2412; the pull requirement is UL 1660 Clause 5.7 (Secureness Forces). The listing is the evidence the product passed. Where an engineering value is not in the standard, we say we do not have it rather than estimate one.
What is the minimum bend radius by size?
Standard liquid-tight conduit: 3/8" and 1/2" – 4"; 3/4" – 5"; 1" – 6"; 1-1/4" – 7"; 1-1/2" – 8"; 2" – 10". Extra-flexible tubing: 1/2" – 2"; 3/4" – 2.5" (item 8452: 2"). Other sizes are on the spec sheets; do not interpolate. The figure is not derived from the NEC; it comes from the UL mandrel test (mandrel twice the listed radius, no cracks) run without wire fill at ambient temperature, so a filled, cold or restrained run is outside what it covers.
What is the voltage rating (or PSI rating) of the conduit?
Liquid-tight conduit has no voltage rating — the limitation is the insulation of the wire installed in it — and we publish temperature information, not a conduit voltage rating. Our non-metallic electrical tubing items (including 8451 and the extra-flexible tubing) are rated 300 V. Conduit is a raceway, not a pressure product, so we do not issue a PSI figure for it.
The inspector wants end bells on the LFNC, or cites NEC 300.4(G) for conductors larger than #4 — what do I use?
End bells are approved for rigid PVC and are not needed on LFNC: NEC 356.28 (2020) allows the ends to be trimmed to remove rough edges, and flexible PVC trims cleanly. For 300.4(G), use a liquid-tight fitting intended for LFNC — our zinc die-cast connectors ship with an insulating throat, which satisfies "an identified fitting providing a smoothly rounded insulating surface". A bell end is not the correct item. We will send the connector spec sheet for the submittal.
Can I glue liquid-tight conduit into a PVC coupling or terminal adapter instead of using a connector?
No. Non-metallic liquid-tight conduit cannot be solvent welded to rigid PVC, and a glued joint is not an approved connection under UL or the NEC: conduit and fittings must be listed for use with each other (NEC 356.6; UL 1660 governs the combination). Terminate with a UL 514B listed liquid-tight connector. To land in rigid PVC, thread the connector into a PVC adapter (female-threaded one side, pipe socket the other) so the solvent-weld joint is between two rigid PVC parts.
Can I use another manufacturer's connectors or couplings on Sealproof liquid-tight conduit?
We do not make or sell other companies' fittings, so we cannot list or certify them. If the fitting is approved under UL 514B and listed for use with liquidtight flexible non-metallic conduit, we believe it is acceptable to use — that is as far as we will go in writing. The governing documents are the other manufacturer's own listing and the AHJ's acceptance, not our opinion. For a listed combination, pair Sealproof LFNC-B with Sealproof connectors.
Is there a torque specification for the connectors, and does the gland cap have to bottom out?
There is no recommended torque or tool under UL 514B; hand-tighten until snug and the gland compresses. The cap need not bottom out on the conduit to be liquidtight: UL 1660 allows roughly twenty thousandths tolerance on conduit OD, so the cap may or may not bottom out. The listing requires the connector to hold the conduit under a 100 lb pull, which a properly hand-tightened hub passes either way. Over-tightening at a tight bend is a common cause of tears.
How long is a continuous length, and do your reels contain couplings or splices?
Standard product is extruded in 100 ft lengths, so reels are joined every 100 ft. On 3/8" through 1" reels the joint is our UL-listed Sealproof coupling (UL 514B, file E197675), approved for continuous use with the conduit and meeting the 125 lb pull requirement; it need not be cut out and wire pulls straight through. Above 1" the joints are taped; a taped splice is not a listed connection and must be cut out. Continuous single-length reels: 1/2" and 3/4" only.
Materials & compliance
Food contact, halogens, and where the compliance statements live.
Is the liquid-tight conduit food grade or NSF listed, and are the connectors?
The standard conduit is made from FDA-compliant material but is not listed as food grade: the compound complies; the product carries no food-grade listing. A dedicated food-grade conduit is a separate product — ask us. The connectors are not FDA compliant and we do not claim an NSF rating for them: they are made for us by outside factories and we have no control method to stand behind a food-contact claim. Check cleaners against a nylon 6 resistance chart, not our PVC chart.
Is the conduit halogen free, or do you offer LSZH conduit?
No. Our non-metallic liquid-tight conduit is a PVC product and PVC contains chlorine, so it is not halogen free, and we do not make LSZH (low smoke zero halogen) conduit. A zero-halogen requirement calls for a nylon-type tubing, which is a different construction. We would rather say so directly than take an order against a rating we cannot meet.
Can you prove the hose is FDA safe — test reports, potable-water or 3-A approval?
We supply a signed company letter stating the resin formulation is FDA formulated. We do not hold third-party FDA test reports, potable-water or medical-device certifications, and we do not recommend these hoses for medical use. "FDA formulated" is not "FDA approved": the letter speaks to the compound, not to approval of the finished hose for your use, which is your determination. Our sanitary hose meets, but is not approved for, 3-A standards.
Where are the REACH, RoHS, Prop 65 and conflict-minerals statements?
On the Compliance page (Resources › Compliance), each as a PDF re-issued in September 2026: REACH SVHC, RoHS 3, California Proposition 65, conflict minerals, phthalates, BPA, FDA food contact and TSE/BSE. For a statement on your own supplier form or for specific part numbers, send us the list and the declaration you need.
Answers reflect our listings and test standards as we understand them and are provided to assist your own design and compliance review; the listing documents (UL Product iQ, CSA, IAPMO) and the authority having jurisdiction govern. Where an answer says we do not hold a rating or issue a document, that is deliberate and we will not soften it in correspondence.
Question not covered here?
Send the part number, the code section or standard you are working to, and what the inspector or certifier is asking for — our team in Elizabeth, NJ will come back to you. Call 1-800-394-3665 or use the form.