What Is Heavy-Duty PVC-Coated Galvanized Spiral Conduit? Types and Selection
Heavy-duty PVC-coated galvanized spiral conduit is a metal cable protection conduit, also known as liquid-tight conduit, whose flexible galvanized steel body is covered by a liquid-tight PVC sheath.
A heavy-duty PVC-coated galvanized spiral conduit is a metal cable protection conduit in which a liquid-tight PVC sheath is fitted over a flexible galvanized steel spiral body; it is also known as liquid-tight spiral conduit. The steel body protects the cable against crushing and impact, while the PVC sheath protects it against water, oil splashes and dust. It is used on cable runs with vibration or movement, such as motor, pump and machine connections, that are also in wet or dirty environments.
Types of metal spiral conduit
| Type | Construction | When to choose |
|---|---|---|
| Galvanized spiral conduit | Bare galvanized steel | Mechanical protection in dry indoor areas |
| PVC-coated galvanized spiral conduit | Galvanized steel with PVC sheath | General use in damp and dusty areas |
| Heavy-duty PVC-coated galvanized spiral conduit | Heavy-duty galvanized steel with liquid-tight PVC sheath | Industrial runs where liquid splashes, dust and mechanical stress occur together |
Selection criteria
- Inner diameter: The inner diameter of the conduit must be comfortably larger than the outer diameter of the cable or cable bundle; leave room for pulling the cable and for heat to dissipate. The number in the LGT code indicates the size series; confirm the inner and outer diameters on the product page or in the manufacturer's dimension table.
- Fitting: Sealing is achieved by the conduit together with a matching fitting, not by the conduit alone. Heavy-duty conduits have a dimension table and a fitting series separate from standard PVC-coated spiral conduit; choose the fitting from the manufacturer's heavy-duty series according to the conduit code. The fitting thread must match the thread of the panel or device entry (PG or metric).
- Environment: If oil, chemicals, high temperature or sunlight are present, check the PVC sheath's resistance to that condition and the operating temperature range in the manufacturer's datasheet.
- Coil length: Choose a coil long enough for the run; a single length without intermediate joints keeps the run sealed.
- Bending: The tightest turn on the route must be larger than the conduit's minimum permitted bending radius.
Common mistakes
- Using a plastic or standard spiral conduit fitting: A fitting made for another series does not grip the heavy-duty conduit fully; sealing and pull-out resistance are lost.
- Not seating the cut end fully in the fitting: The cut edge of the steel spiral damages cable insulation; the conduit end must go all the way into the fitting.
- Treating the conduit as the protective conductor: Flexible metal conduit does not replace the protective (PE) conductor; earthing is done with a separate conductor in the cable.
- Sharp bends: The sheath folds, the inner cross-section narrows and the cable can no longer be pulled.
Related standard
- IEC 61386-23: Particular requirements for flexible conduit systems within conduit systems for cable management. The catalog product names carry no declaration of conformity to this standard; request the certificate from the manufacturer if needed.
Heavy-duty spiral conduits in the catalog
All 9 active products in the Heavy-Duty PVC-Coated Galvanized Spiral Conduits category are from the Ortaç LGT series:
| Code | Coil | Sold |
|---|---|---|
| LGT 10, LGT 12, LGT 16, LGT 21, LGT 27 | 30 m | By the metre, in multiples of 30 m |
| LGT 35, LGT 40, LGT 51 | 15 m | By the metre, in multiples of 15 m |
| LGT 63 | 7.5 m | By the piece (coil) |
Prices and lead times for the LGT series are given on quotation. For lighter conditions see the PVC-Coated Galvanized Spiral Conduits category, and for runs that need an additional steel wire braid layer see Steel Wire Braided PVC-Coated Galvanized Spiral Conduits. The Spiral Conduit Fittings category has Ortaç brass fittings as well as plastic ones; choose a fitting that matches the outer diameter of the LGT series from the datasheet.
Frequently asked questions
What does liquid-tight spiral conduit mean?
It means a spiral conduit that keeps liquids out. When used with a matching fitting, PVC-sheathed metal spiral conduit prevents water and oil from entering the cable run. In the catalog this type is listed as heavy-duty PVC-coated galvanized spiral conduit.
What is the difference between heavy-duty and standard PVC-coated galvanized spiral conduit?
Both are PVC-sheathed galvanized steel conduits. The heavy-duty type is for industrial runs where liquids, dust and mechanical stress occur together; its dimensions follow a separate table and it is connected with a separate fitting series. A fitting from one series may therefore not fit the other.
In what lengths is LGT spiral conduit sold?
Codes LGT 10–27 are sold by the metre in multiples of a 30 m coil, and codes LGT 35–51 in multiples of a 15 m coil. LGT 63 is sold by the piece as a single 7.5 m coil.
Can spiral conduit be used instead of an earthing conductor?
No. The joints and fitting transitions of flexible metal conduit do not form a continuous and reliable protective conductor; run a separate protective (PE) conductor in the cable.