1/2 inch flexible conduit is a trade-size raceway for routing and protecting wiring where rigid pipe won’t fit. The rule: pick liquidtight metal for physical abuse, nonmetallic for corrosive or wet spots, and plastic for light indoor runs.
A 1/2-inch flexible conduit is not half an inch wide. That number is a trade size — a naming convention — and actual inside and outside diameters shift with every construction type and manufacturer.
The sections below cover published dimensions from Southwire and ABB documentation, what each material handles well, and where a run of this conduit belongs.
Why The Diameter Never Matches The Label
Trade size signals the nominal size class of the raceway and the fittings designed to match it, not a measurable dimension. Two products sold as 1/2 inch can carry noticeably different outside diameters.
Southwire’s 1/2″ Titan metal-flex conduit page lists a 0.622 in inner-jacket diameter, an approximate 0.820 in outside diameter, and a 6.5 in minimum bend radius. ABB’s liquidtight nonmetallic specification sheet lists an average I.D. of 0.627 in and an average O.D. of 0.83 in on a 1000 ft reel. Same trade size, different numbers.
That gap is why fittings are matched to trade size rather than to a tape measure.
Dimensions And Temperature Limits By Type
Bend radius and temperature rating decide whether a product works in your install, and they vary more than most people expect. A 1 in bend radius on one plastic product versus 6.5 in on Southwire’s metal version is the difference between fitting inside a small junction box and not.
| Conduit Type | Published Dimensions | Temperature Range |
|---|---|---|
| Liquidtight flexible metal (Southwire Titan, type UL) | 0.622 in I.D., ~0.820 in O.D., 6.5 in bend radius | Max 176 °F on comparable metal SKUs |
| Liquidtight flexible nonmetallic (ABB/T&B sheet) | 0.627 in average I.D., 0.83 in average O.D., 1000 ft reel | Nonmetallic gray construction, specs by SKU |
| Plastic liquidtight, PVC-based listing | 0.62 in I.D., 0.91 in O.D., 3 in bend radius | Max 176 °F |
| Flexible plastic, tighter-bend listing | 0.62 in I.D., 0.84 in O.D., 1 in bend radius | 0 °F to 140 °F |
| ABB 12005-200 (PVC) | 0.56 in I.D., 0.84 in O.D., 200 ft length | Outdoor service rated |
| Common purchase lengths, all types | 25 ft, 100 ft, 250 ft, 500 ft, 1000 ft | Varies by supplier and construction |
| Low-temperature metal SKUs | Same 1/2 in trade size class | Min −30 °F or 14 °F depending on SKU |
Southwire publishes its Titan type UL liquidtight flexible metal conduit specifications in full if you want the source numbers before ordering.
To compare specific products before buying, our roundup of 1/2 inch flexible conduit options walks through what to look for.
Where Each Type Actually Belongs
The right choice comes down to whether the run needs liquid protection, metallic strength, or just flexible routing.
- Liquidtight flexible metal conduit — for flexible runs needing both liquid resistance and metallic physical protection. Some listings are outdoor-only, and approvals vary by SKU among UL, CSA, ANSI, and NFPA. Check the specific page.
- Liquidtight flexible nonmetallic conduit — for wet or corrosive environments where nonmetallic construction is wanted. ABB’s documentation identifies the product as non-metallic, gray, and 1/2 in.
- Plastic liquidtight conduit — for lighter-duty routing. One cited listing shows PVC construction with UV resistance and water-proof properties, suiting sun-exposed outdoor runs where metal would corrode.
- Flexible metal (non-liquidtight) conduit — for dry indoor locations where physical protection matters more than moisture sealing.
Not every 1/2-inch product works in every location. Outdoor-only listings, UV-rated plastics, and lower temperature limits all exist in this size class, and picking the wrong variant for the environment is the most common avoidable error.
Installation Steps And The Mistakes That Cause Leaks
Getting a liquidtight seal comes down to a clean cut and correctly seated fittings.
- Cut the conduit to length.
- Ensure a clean, burr-free cut — a ragged edge prevents the seal from seating.
- Push the conduit fully onto the connector ferrule.
- Tighten the sealing nut to create the liquid-tight seal.
- For straight or 90-degree fittings, position the fixed steel ring and EPDM washer correctly before tightening.
Done right, the conduit sits flush against the fitting shoulder with no gap at the nut and no exposed ferrule threads.
Three mistakes to avoid: assuming all 1/2-inch conduit shares the same diameter or bend radius, confusing trade size with actual I.D. or O.D., and using an outdoor-only or low-temperature-rated product in the wrong spot.
FAQs
Is 1/2 inch flexible conduit the same as 1/2 inch rigid pipe?
No. Both use trade size labeling, but flexible conduit bends by design while rigid pipe does not. Diameter specs also differ, so fittings are not interchangeable across the two families.
Can I use 1/2 inch flexible conduit outdoors?
Some types are rated for it and some are not. Several liquidtight metal listings specify outdoor-only use, and some plastic versions carry UV resistance. Check the individual product page before installing outside.
Why does my 1/2 inch conduit measure larger than 0.5 inches?
Because trade size is a nominal class name, not a measurement. Published outside diameters for 1/2-inch products run from about 0.82 in to 0.91 in depending on construction, and inside diameters also vary.
References & Sources
- Southwire. “Titan2 Type UL Liquidtight Flexible Metal Conduit” Source for 0.622 in inner-jacket diameter, 0.820 in approximate OD, and 6.5 in minimum bend radius.
- ABB / T&B. “Liquidtight Flexible Non-Metallic Conduit & Fittings” Specification sheet confirming 1/2 in size, 0.627 in average ID, 0.83 in average OD, and 1000 ft reel length.
- ABB. “eCatalog 12005-200” Lists 1/2 in trade size, 0.84 in OD, 0.56 in ID, 200 ft length, and PVC material.
