Spiral Conduits Selection Guide
Spiral conduits split into plastic (polyamide, polypropylene) and metal groups; material, temperature range and slit or closed construction drive the choice.
This guide covers the points to look at when choosing products in the Spiral Conduits category.
Plastic spiral conduits
- Polyamide spiral conduits: corrugated plastic conduits. For the Ortaç PA6 series, an operating range of -40 °C to +120 °C, UL94 V2 flame class and halogen-free construction are stated.
- Polypropylene spiral conduits: in Ortaç data the operating range is -20 °C to +90 °C, and acid resistance is stated.
- Slit polyamide spiral conduits and slit polypropylene conduits: they are slit lengthwise, so they can be fitted afterwards over cables whose ends are already connected. Because of the slit, they are not sealed like a closed conduit.
Oval-section conduits and plastic conduits with a ready-made pull wire inside are in separate subcategories.
Metal and braided spiral conduits
- Galvanized spiral conduits: conduits made of galvanized steel, without a jacket. In Ortaç data the operating range is -50 °C to +300 °C and the protection rating is IP40; they withstand impact and temperature but are not sealed against liquid and fine dust.
- PVC-coated galvanized spiral conduits: the steel body is covered with a PVC jacket. For this series Ortaç gives IP54-IP67 and -25 °C to +90 °C; the upper temperature limit is markedly lower than for the unjacketed conduit.
- Heavy-duty PVC-coated galvanized spiral conduits: LGT-coded conduits, also known as "liquid tight"; in Ortaç data IP66 and -20 °C to +105 °C.
- Steel wire braided spiral conduits: a corrugated polyamide conduit covered with a steel wire braid; the braid surface protects against abrasion and friction. Braided conduits with galvanized and PVC-coated galvanized bodies are in separate subcategories; for the braided series with a galvanized body, Ortaç also states an EMC shielding property.
- Galvanized spiral conduits with pull wire: models with a wire inside for pulling cable; a PVC-coated version is also listed.
The difference between helical spiral and spiral conduit
Helical spiral conduits are not a closed conduit but an open helical band wound around a cable bundle. They gather the bundle, protect it against friction and allow cables to be taken out at any desired point; they are not sealed against dust and liquid. Konsan helical spirals are referred to in the product name by a winding pitch such as 7.5-30 mm. Where sealing or crush resistance is required, a corrugated or metal spiral conduit is chosen.
How to read the size: nominal size, inner diameter and outer diameter
The meaning of the number in the name varies by series. In Ortaç metal conduits this number is the inner diameter: a nominal 11 galvanized conduit has an inner diameter of 11 mm and an outer diameter of 14 mm, and the PVC-coated one has an outer diameter of 15 mm. In Ortaç plastic corrugated conduits the nominal size is close to the inner diameter but not equal at every size: a nominal 29 conduit has an inner diameter of 29 mm and an outer diameter of 34.5 mm, whereas a nominal 21 conduit has an inner diameter of 23.5 mm and an outer diameter of 28.4 mm. In Mutlusan products too, the millimeter value in the name is not the same as the inner and outer diameter given on the product card. Make the selection not by the number in the name but by the inner and outer diameter on the product card or in the manufacturer's table.
The inner diameter is selected according to the cable bundle that will pass through and any end parts such as plugs or lugs; leave some margin so the cables can be pulled in without jamming. The type and outer diameter of the conduit determine the fitting. For plastic corrugated conduits, snap-on polyamide fittings are matched to the compatible conduit outer diameter value on the product card. Ortaç states brass fittings with fixed or rotating thread for galvanized and PVC-coated conduits (in the store under codes MPR and MDP), and external-type fittings with code LSR for heavy-duty and steel wire braided conduits. All of these are under Spiral Conduit Fittings; T and Y distributors for branching off and fixing cable clips are in the Spiral Conduit Distributors and Connectors category.
Choosing by environment
The protection rating belongs not to the conduit alone but to the system formed by the conduit and the fitting together; the requirements for flexible conduit systems are defined by IEC 61386-23. Where liquid splashes, a PVC-coated or heavy-duty metal conduit stands out; at high temperature, an unjacketed galvanized conduit; for machine wiring where light weight is wanted, a polyamide conduit. For the effect of oil and chemicals, use the manufacturer data of the selected series as the basis. Ortaç states UV resistance in many series in black and on request; confirm this property before ordering for outdoor use.
Brands in this category
- Ortaç: most of the plastic and metal conduits. The code gives the type: OGPA gray polyamide, OSPA black polyamide, OGPP and OSPP polypropylene, a trailing Y slit, OCS galvanized, OPCS PVC-coated galvanized.
- Mutlusan: black plastic spiral conduits, with and without pull wire.
- Konsan: white and black helical cable spirals, in 10-meter packs.
Ordering notes
Conduits are listed by the meter. The 25, 50 or 100 meters in the product name is the manufacturer's coil length and may be stated on the product card as the minimum order quantity; check the card before entering the quantity. A significant share of the products are lead-time items; their delivery time is confirmed before the order. If you need fittings and cable clips with the conduit, choose them together according to the same outer diameter.
Comparison and selection table
| Selection Criterion | Polyamide (PA6) / Polypropylene (PP) Corrugated Conduit | Galvanized Steel / PVC-Coated Flexible Metal Conduit | Flush-Mount / Concrete PVC Corrugated Conduit |
|---|---|---|---|
| Mechanical & Thermal | Highly flexible, oil/chemical resistant, halogen-free (PA6) | Crush, metal-chip, rodent & high-temperature resistant | Light, medium or heavy-duty crush rating for plaster & screed |
| Ingress Protection | Achieves IP66 / IP68 with matching snap-fit conduit glands | PVC-jacketed steel + liquid-tight metal gland reaches IP65/IP67 | Protects single-core NYA (H07V-U) conductors between wall boxes |
| Size Designation | Nominal/OD (PG7–PG48 or Ø10, Ø16, Ø20, Ø25, Ø32, Ø50 mm) | Trade sizes 3/8", 1/2", 3/4", 1", 1 1/4", 1 1/2", 2" | Outer diameter Ø14, Ø16, Ø18, Ø20, Ø25, Ø32, Ø40, Ø50 mm |
| Typical Application | Machine tools, robotics, sensor harnesses & panel doors | CNC machining centers, foundries, outdoor motor terminal boxes | Residential & commercial concealed wall/floor wiring |
Frequently asked questions
Is the spiral conduit size the inner or the outer diameter?
It varies by series. In Ortaç metal conduits the number in the name is the inner diameter; a nominal 11 galvanized conduit has an inner diameter of 11 mm and an outer diameter of 14 mm. In Ortaç plastic corrugated conduits, although the nominal size is close to the inner diameter, it may not equal it: a nominal 21 conduit has an inner diameter of 23.5 mm and an outer diameter of 28.4 mm. Look at the inner diameter for the cable bundle to fit and at the outer diameter for the fitting to match.
When is a slit spiral conduit preferred?
If the cable ends are already connected or carry a plug, socket or lug, they cannot be passed through a closed conduit; a slit conduit is opened along its lengthwise slit and fitted over the existing cable bundle. It saves time in maintenance and when adding cables later. Because of the slit it does not behave like a conduit that is sealed against dust and liquid; on lines where sealing is required, a closed conduit and a suitable fitting are used.
What is the difference between polyamide and polypropylene spiral conduit?
Both are corrugated plastic conduits; the difference is in the material properties. In Ortaç data, polyamide (PA6) conduit works in the range -40 °C to +120 °C and polypropylene conduit in the range -20 °C to +90 °C. Halogen-free construction and UL94 V2 flame class are stated for the polyamide series, and acid resistance for the polypropylene series. In a hot or cold environment polyamide is considered; where chemical exposure is decisive, polypropylene is considered according to the manufacturer data.
Does galvanized spiral conduit protect against water and dust?
Unjacketed galvanized spiral conduit is not sealed against liquid and fine dust; Ortaç gives IP40 for this conduit. Where liquid and dust are present, PVC-coated galvanized conduit (IP54-IP67 in the manufacturer data) or heavy-duty conduit (IP66) is chosen. The protection rating belongs to the connection formed by the conduit and a suitable fitting together; match the fitting to the conduit's type and outer diameter.
Are helical spiral and corrugated spiral conduit the same thing?
No. A helical spiral is an open helical band wound around a cable bundle; it gathers the bundle and lets cables be taken out through the gaps, but it does not form a closed jacket. A corrugated spiral conduit, on the other hand, is a closed flexible conduit through which the cables are passed, and it is connected to a panel or device with a fitting. Helical spiral is chosen for organizing, and conduit for mechanical protection and sealing.
Which fitting is used on a spiral conduit?
For plastic corrugated conduits, polyamide spiral fittings that engage the corrugations of the conduit are used. Ortaç states brass fittings with fixed or rotating thread for galvanized and PVC-coated metal conduits, and external-type brass fittings for heavy-duty and steel wire braided conduits. A fitting is selected by two dimensions: the diameter of the conduit and the thread size on the panel side. A cable gland is not designed to hold a spiral conduit; the two are separate product groups.