Cable conduits are one of the most fundamental components in any electrical installation, yet they rarely attract much detailed attention. Most people know that conduit protects cables, but the question of which type to use, in which environment, and why, is one that catches a surprising number of people out.
This guide covers what cable conduits actually are, how they work, the main types available and their differences, the environments and applications each one is suited for, and the practical considerations that matter when specifying and installing conduit systems. By the end you will have a clear and complete picture of conduit as a product category and a confident basis for making the right selection decisions.
What Is a Cable Conduit?
A cable conduit is a protective tube or channel through which electrical cables are routed. The conduit surrounds the cables along their run, shielding them from physical damage, moisture, dust, chemicals, and other environmental hazards. It also provides a structured pathway that keeps cable runs organised, accessible for future work, and protected from accidental interference.
The concept is straightforward: instead of laying cables directly against a surface or through a building structure with only their own insulation and sheath for protection, you route them through a dedicated tube. That tube becomes the primary interface with the environment, and the cables inside it are protected from whatever the environment throws at the installation over its lifetime.
Conduit is used in virtually every type of electrical installation: domestic, commercial, industrial, infrastructure, marine, and more. The specific type of conduit varies significantly depending on the application, but the fundamental principle is consistent across all of them.
It is worth distinguishing conduit from cable tray, trunking, and duct. Cable tray and trunking are open or partially enclosed cable management systems that support cables rather than fully enclosing them. Duct typically refers to larger underground or in-wall channels for multiple cable runs. Conduit is a fully enclosed circular or oval tube, and this distinction affects what kind of protection it provides and which applications it is right for. Conduit works as part of a complete cable management system alongside components such as cable glands, cable ties, and cable cleats, each of which handles a different aspect of securing and managing the cable run.
Why Use Conduit? The Core Benefits
Before getting into the types, it is useful to understand precisely what conduit delivers and why it is specified rather than simply running cables directly.
Physical Protection
The most immediate function of conduit is mechanical protection. Cables inside a conduit are shielded from impact, abrasion, crushing, and the kind of accidental damage that occurs during construction, maintenance, and everyday building activity. In industrial environments this protection is particularly important: machinery vibration, forklift traffic, falling objects, and regular maintenance work all create risks that a cable running without protection would not survive reliably over the long term.
Environmental Protection
Depending on the conduit material and construction, it can provide protection against moisture, dust, oils, chemicals, and UV radiation. This is especially relevant in outdoor installations, in wet or damp environments such as plant rooms and food processing facilities, and in locations where chemical exposure is a routine part of the operating environment.
Fire Containment
Steel conduit in particular plays a role in fire containment. Unlike a cable sheath, which will eventually burn if a fire reaches it, a steel conduit does not add fuel to a fire. It can also slow the spread of a fire along a cable route by containing burning or degraded material within the tube.
Future Access and Replaceability
One of the underappreciated advantages of conduit is that cables can be withdrawn and replaced without disturbing the building fabric or the structural installation. If a cable fails, or if the installation needs to be upgraded to a higher-rated cable, the conduit stays in place and only the cable inside it changes. In a surface-mounted installation without conduit, replacing a damaged cable often means significant disruption to the wall or ceiling finish.
Electromagnetic Shielding
Steel conduit provides a degree of electromagnetic shielding for the cables running inside it. This is relevant in environments where sensitive equipment is nearby, or where the cables themselves carry signals that could be affected by external interference. Metal conduit, when properly earthed, acts as a Faraday cage around the cable.
Compliance and Certification
Many project specifications and wiring regulations require conduit in specific locations as a mandatory protection measure rather than an optional enhancement. Understanding which type of conduit is required by the applicable standard for a given installation is part of the specification process.
Types of Cable Conduit
Conduit comes in several main types, each with different material properties, strengths, limitations, and appropriate applications. The three principal categories are galvanised steel (GI) conduit, PVC conduit, and flexible conduit.
GI Conduit (Galvanised Iron / Galvanised Steel Conduit)
GI conduit is the standard specification for industrial, commercial, and infrastructure electrical installations where mechanical strength and durability are the priority. The abbreviation GI stands for galvanised iron, though the material is more accurately described as galvanised steel: a cold-rolled steel tube that has been hot-dip galvanised to give it corrosion resistance. It is manufactured to BS4568 in the UK and IEC61386 internationally, both of which define the dimensional, mechanical, and electrical requirements for steel conduit systems.
The GI conduit and accessories range covers rigid steel conduit in standard sizes along with a full set of fittings including junction boxes, adaptable boxes, conduit fittings, saddles, switch and socket boxes, and covers. This accessory range matters because a conduit system is only as good as its fittings: a rigid steel conduit run with poorly fitted joints or inadequate boxes loses much of the protection value of the conduit itself.
The properties that make GI conduit the specification of choice in demanding installations are:
- Exceptional mechanical strength: Hot-dipped galvanised steel withstands impact, crush loads, and physical interference that would split or deform a PVC or plastic conduit. In industrial environments with vehicle traffic, heavy machinery, or regular physical activity near cable routes, steel conduit is the only credible option.
- Fire resistance: Steel does not burn. A GI conduit system will survive a fire far longer than any plastic conduit, and during that time it continues to protect the cables inside it. In installations where circuit integrity during a fire is a requirement, such as fire alarm circuits, emergency lighting, and safety systems, steel conduit is frequently specified.
- Corrosion resistance: The hot-dip galvanising process deposits a thick layer of zinc onto the steel, which provides durable corrosion protection. This is sufficient for most indoor and outdoor applications in normal atmospheric conditions. In highly corrosive environments such as marine, coastal, or chemical processing installations, additional protection such as PVC-coated conduit may be required.
- Earthing continuity: A properly installed and jointed GI conduit system provides earthing continuity along its entire length. The conduit itself forms part of the earthing system, which means the cables inside it have a continuous earth path without needing a separate earth conductor for that purpose.
- Long service life: A correctly installed GI conduit system has a service life measured in decades. The initial cost is higher than PVC, but the lifecycle cost including maintenance and replacement is often lower in environments where plastic conduit would need to be replaced multiple times.
Where GI Conduit Is Used
- Industrial factories, processing plants, and warehouses
- Power stations, substations, and energy infrastructure
- Oil and gas facilities and offshore installations
- Commercial buildings where surface-mounted conduit will be exposed
- Locations requiring circuit integrity under fire conditions
- Underground and buried installations requiring high crush resistance
- Any environment with significant risk of physical damage to the conduit
Standards Note: GI conduit manufactured to BS4568 and IEC61386 carries defined ratings for mechanical impact resistance, compression resistance, and electrical continuity. Always verify that the conduit you specify is manufactured to the applicable standard and carries the relevant certification, particularly for installations that will be subject to third-party inspection. |
PVC Conduit
PVC conduit is manufactured from rigid polyvinyl chloride and is the standard choice for domestic and light commercial electrical installations. It is lighter than steel, easier to cut and join, does not require threading, and is available at a lower cost. The PVC conduit and accessories range covers standard rigid PVC conduit in a wide range of diameters alongside the full complement of fittings, bends, junction boxes, and accessories needed for a complete installation.
The key characteristics of PVC conduit are:
- Electrical insulation: Unlike steel conduit, PVC does not conduct electricity. This means it cannot form part of the earthing system, and it also means that a fault within the conduit does not create a risk of the conduit itself becoming live. In domestic and light commercial installations this is generally an advantage rather than a limitation.
- Corrosion immunity: PVC is inherently resistant to the corrosion processes that affect metals. It will not rust, oxidise, or degrade in the presence of moisture in the way that unprotected steel would. This makes it appropriate for damp and wet locations where galvanised steel conduit might be over-specified.
- Chemical resistance: PVC has good resistance to a wide range of acids, alkalis, and solvents, which makes it suitable for use in light chemical environments and laboratories where occasional chemical exposure is possible.
- UV resistance: Standard grey PVC conduit has limited UV resistance and is not suitable for prolonged outdoor exposure without UV stabilisation. UV-stabilised black PVC conduit is available for outdoor applications where the conduit will be in direct sunlight.
- Temperature limitations: PVC becomes brittle at low temperatures and softens at elevated temperatures. Standard PVC conduit is not appropriate for installations where the ambient temperature regularly falls below minus 5°C or exceeds around 60°C. In these conditions, steel or specialist conduit materials are needed.
- Lower mechanical strength: PVC conduit provides good protection against light physical contact and incidental damage, but it will split or deform under significant impact or crush loading. It is not suitable in locations where vehicles, heavy equipment, or heavy foot traffic create mechanical hazards.
Where PVC Conduit Is Used
- Domestic wiring: surface-mounted runs, ring main circuits, spur cables
- Commercial offices and retail spaces with surface-mounted cable runs
- Damp and wet locations such as bathrooms, kitchens, and plant rooms
- Laboratories and light chemical environments
- Locations where the conduit will be plastered or concealed in wall chases
- Overhead cable management in warehouses and storage facilities where mechanical risk is low
GI PVC Flexible Conduit
Flexible conduit combines a galvanised steel interlocked spiral construction with a PVC coating, giving it both mechanical strength and environmental protection while allowing the conduit to be bent and flexed during installation. The GI PVC flexible conduit is specifically designed for applications where rigid conduit cannot be used because of the geometry of the installation or because the conduit needs to flex in service.
The defining characteristic of flexible conduit is that it can be bent by hand to follow curved routes and can accommodate changes in direction without fittings. This makes it ideal for the final connection between a rigid conduit run and a piece of equipment, where the rigid conduit terminates near the equipment and a short flexible section bridges the gap to the equipment entry point.
Key applications for GI PVC flexible conduit include:
- Final connections to machinery and equipment: Equipment that vibrates during operation cannot be directly connected to rigid conduit without transmitting that vibration into the conduit system and eventually loosening joints or fatiguing the conduit at the connection point. A flexible section absorbs the vibration and protects the rigid system.
- Elevator and lift installations: Cable routes that travel through lift shafts and connect to elevator equipment need to accommodate movement. Flexible conduit is the standard solution for the dynamic sections of these installations.
- CCTV camera installations: Camera housings that need to be repositioned or adjusted require a flexible connection between the fixed conduit and the camera body. GI PVC flexible conduit handles this well, particularly in outdoor applications where weather resistance is needed.
- Metro stations and transit infrastructure: These installations have complex cable routes through structures that include vibrating components, curved surfaces, and areas where rigid conduit cannot be routed without multiple fittings. Flexible conduit simplifies installation and reduces the number of joints in the system.
- Tight-spot installations: Anywhere that a rigid conduit cannot be manoeuvred into position, flexible conduit provides the solution. It can be fed into confined spaces, bent around obstacles, and connected to entry points that are not accessible to rigid tube.
- Outdoor installations requiring water tightness: The PVC coating on the GI flexible conduit provides a seal against water ingress at the bends and through the conduit wall, making it suitable for outdoor use where moisture resistance is needed at the conduit itself rather than just at the fittings.
How to Choose the Right Conduit Type
The selection process for conduit follows a logical sequence that eliminates options based on the requirements of the application.
Start with the Environment
The installation environment is the primary filter. Ask the following questions: Is the installation indoors or outdoors? Is the conduit exposed or concealed? What is the ambient temperature range? Is there moisture, chemical exposure, or UV radiation? Is there a risk of physical impact or mechanical damage?
If the environment is harsh, industrial, or involves significant mechanical risk, GI conduit is the starting point. If the environment is standard domestic or light commercial with no unusual hazards, PVC conduit is appropriate. If the installation involves connection to moving or vibrating equipment, or if the route requires flexibility, flexible conduit is needed for at least part of the run.
Consider the Circuit Requirements
Some circuits have specific conduit requirements imposed by regulations or the project specification. Emergency lighting circuits, fire alarm cables, and other life-safety systems often require steel conduit to maintain circuit integrity under fire conditions. Signal control cables running in environments with electromagnetic interference may benefit from the shielding that a properly earthed steel conduit provides. For standard power distribution and lighting circuits in normal environments, there is usually more flexibility in the conduit type selection.
Consider the Cable Type
The type of cable being installed inside the conduit influences the conduit selection. H07RN-F rubber flexible cables are typically used in portable or temporary applications and are not routinely installed in conduit. Fixed wiring cables, signal cables, and power distribution cables are the primary candidates for conduit installation. The cable outer diameter determines the required conduit internal diameter, and the number of cables being installed together determines whether a single conduit or multiple conduits are needed.
Think About Future Access
If there is any possibility that the cables will need to be changed, upgraded, or added to in the future, conduit is the right choice over direct cable routing. This is particularly relevant in commercial buildings where tenant fit-outs change, in industrial facilities where processes evolve, and in any installation where future proofing has value.
Factor In Installation Practicality
Steel conduit requires threading at joints and entry points, which adds time to the installation. PVC conduit uses solvent-welded fittings or push-fit systems that are faster to install. Flexible conduit can be cut to length and connected with compression fittings quickly. The practical aspects of installation matter particularly where labour cost is a significant proportion of the project budget. Using cable pulling lubricant during the cable pull significantly reduces the effort required to draw cables through any conduit run, and reduces the risk of damaging the cable sheath during installation, particularly in long runs or runs with multiple bends.
Conduit Sizing: How to Calculate the Right Diameter
Choosing the correct conduit diameter is a critical step that is often underestimated. An undersized conduit makes cable pulling extremely difficult, risks damaging cable sheaths during installation, and may not be compliant with the applicable wiring regulations. An oversized conduit wastes space and material.
The Space Factor Rule
The governing principle for conduit sizing is the space factor, which limits the proportion of the conduit internal cross-sectional area that can be occupied by cables. The relevant UK standard (BS 7671, the IET Wiring Regulations) defines space factors for different installation conditions. As a practical rule:
- For a single cable in a conduit: the cable should occupy no more than 40% of the conduit internal cross-sectional area
- For multiple cables in a conduit: the cables should collectively occupy no more than 40% of the conduit internal cross-sectional area for straight runs
- The space factor reduces further when the conduit includes bends, because cables are harder to pull around bends and more space is needed to avoid damage
The Calculation
To calculate the required conduit size, add up the cross-sectional areas of all the cables to be installed in the conduit (using the overall outer diameter of each cable), then select a conduit whose internal cross-sectional area is at least 2.5 times that total (to achieve the 40% space factor).
In practice, conduit sizing tables are available from manufacturers and in wiring regulations publications that express this in usable terms: given a combination of cable types and quantities, the table tells you the minimum conduit diameter required. Using these tables is faster than working from first principles for each run.
Practical Conduit Sizes
Standard conduit is available in nominal sizes of 16mm, 20mm, 25mm, 32mm, 40mm, and 50mm internal diameter for most applications, with larger sizes available for specialist uses. The 20mm and 25mm sizes cover the majority of standard wiring applications in domestic and light commercial installations. Industrial installations often require 32mm and above, particularly where multicore power cables are being installed.
Practical Tip: Always size the conduit for the cables you plan to install now, plus allow spare capacity for future additions. Adding a conduit after the building work is complete is significantly more expensive than installing a slightly larger conduit during the initial fit-out. The cost difference between a 20mm and a 25mm conduit is negligible compared to the cost of remedial work. |
Conduit Installation: What You Need to Know
Installing conduit correctly determines whether it delivers the protection it is designed to provide. The main installation considerations apply across all conduit types, with some specific points for steel and flexible conduit.
Planning the Route
Before any conduit is fixed in position, the full cable route should be planned. This includes identifying where the conduit will be surface mounted or concealed, where bends occur, where junction boxes and pull points are needed, and how the conduit will be supported. Routes with the fewest bends and the shortest lengths make cable pulling significantly easier.
As a guideline, IET Wiring Regulations recommend that a conduit run should not have more than the equivalent of four right-angle bends between draw-in points. Every bend adds to the pulling force required to draw cables through the conduit, and beyond a certain number of bends it becomes impossible to pull cables without risking damage.
Supporting the Conduit
Conduit must be properly supported at intervals that prevent sagging and movement. For horizontal runs of 20mm rigid conduit, supports should typically be no more than 1.25m apart. Larger conduit sizes and vertical runs have different support interval requirements, which are specified in the relevant installation standards. Saddle clips and conduit brackets are the standard fixing method.
Making Bends in Rigid Conduit
PVC conduit is bent using a bending spring inserted into the conduit, which supports the wall of the tube during bending and prevents it from kinking or collapsing. Gentle heat from a hot air gun makes the PVC pliable enough to bend without stress. Steel conduit requires a conduit bending tool, which uses a former to shape the tube around the correct radius without deforming the cross-section.
For tight bends or complex changes of direction, proprietary fittings are a cleaner and more reliable solution than site-formed bends, particularly for steel conduit where forming consistent bends requires practice and the right equipment.
Cable Pulling
Drawing cables through a completed conduit run is a skill that is easy to underestimate. Short runs with no bends pull easily. Long runs, runs with multiple bends, or runs with multiple cables all require significantly more force. Cable pulling lubricant should always be used on any run longer than a few metres or any run with more than one bend. The lubricant reduces friction between the cable sheath and the conduit wall, reduces the force required to pull the cable, and reduces the risk of sheath damage. The guide to what cable pulling lubricants are and why they are needed covers the different types and how to select the right one for your installation.
Sealing and Waterproofing
In outdoor, underground, or wet locations, the entry points of the conduit, where cables enter junction boxes, equipment, and termination points, need to be properly sealed against moisture ingress. This is typically done using appropriate conduit fittings and, where needed, conduit sealing compound. For steel conduit running into equipment enclosures, the correct
cable glands at the equipment entry point maintain the integrity of the protection provided by the conduit system up to the point of termination inside the equipment.
Earthing Steel Conduit
A steel conduit system must be properly earthed to be safe. The conduit is connected to the earth terminal at the distribution board end, and continuity is maintained through the joints along the length of the run. Conduit joints that are not properly made with conductive fittings and correct tightening will break the earth continuity. This should be verified during installation with a continuity test before cables are pulled through.
Conduit in Specific Environments
Different sectors and environments have their own particular conduit requirements. Here is how the selection plays out in the most common scenarios.
Domestic Buildings
The majority of domestic conduit installations use PVC conduit in standard sizes. Surface-mounted PVC conduit is used for extensions, additions to existing circuits, and new installations where chasing the wall is not practical. Concealed PVC conduit is installed in wall chases or behind plasterboard during construction or renovation. The standard sizes for domestic work are 20mm and 25mm.
Commercial and Office Buildings
Commercial buildings typically use a combination of conduit types depending on the location. Plant rooms, risers, and areas with mechanical exposure use GI conduit. Office fit-out areas often use PVC conduit or cable trunking. In high-rise buildings, fire compartmentation requirements may impose steel conduit in specific locations to prevent fire spread along cable routes.
Industrial Facilities
Industrial installations are the primary domain of GI conduit. The mechanical demands of factory environments, combined with the requirement for long-term reliability of power distribution circuits, make steel conduit the default specification. It is used for all surface-mounted power and control wiring, for cable routes near machinery, and for connections to motor control centres and distribution boards. Signal and control cables, including signal control cables and the type of cables discussed in the guide to what control cables are, are often run in separate conduit systems from power cables to avoid electromagnetic interference.
Outdoor and Underground Installations
Outdoor surface-mounted conduit should be GI conduit with appropriate anti-corrosion protection, or UV-stabilised PVC conduit for lighter-duty applications. For underground installations, the conduit must have sufficient crush strength to withstand the soil loading and any surface traffic above it. This typically means heavy-duty PVC ducting or GI conduit, with steel conduit preferred where the burial depth is shallow or where surface loading is significant.
Hazardous Areas
In locations classified as hazardous areas under ATEX or equivalent regulations, such as petrochemical facilities, paint booths, and solvent storage areas, specially rated conduit systems are required. These are typically steel conduit with Ex-rated fittings and sealing bushes that prevent flammable gases or vapours from travelling along the conduit and reaching non-explosion-protected equipment. This is a specialist area that requires engineering expertise and the use of certified components throughout.
Marine and Coastal Environments
In marine environments and coastal locations where salt air accelerates corrosion, standard GI conduit may not provide adequate long-term protection. Options include stainless steel conduit, PVC-coated steel conduit, or specialist marine-grade conduit systems. The flexible conduit with PVC coating is particularly useful in marine installations for its combination of corrosion resistance and flexibility in connecting to equipment on vessels.
Conduit Accessories: Completing the System
A conduit system is more than just the tube. The accessories make the system complete and determine whether the protection the conduit provides is maintained consistently throughout the installation.
Junction Boxes and Adaptable Boxes
Junction boxes are positioned at intervals along conduit runs to provide pull points for cable installation, to allow cables to be jointed or connected, and to provide inspection access. Adaptable boxes give additional flexibility in installation where standard junction boxes do not fit the geometry of the installation. In GI conduit systems, these boxes are typically galvanised steel with threaded or compression-fit conduit entry points.
Conduit Fittings and Couplers
Rigid conduit lengths are joined using couplers or locknuts, and direction changes are handled using standard bends (30 degrees, 45 degrees, 90 degrees), tees, and elbows. Using the correct fittings maintains the mechanical and electrical continuity of the conduit system. Improvised or poorly fitted joints create weak points where moisture can enter, where earth continuity may be broken, and where the conduit may eventually pull apart.
Saddles and Supports
Conduit saddles are the standard fixing for surface-mounted conduit. They are available in sizes to match each conduit diameter and in materials matched to the conduit type: standard or heavy-duty galvanised saddles for steel conduit, and PVC or nylon saddles for PVC conduit. Saddle spacing should follow the recommendations for the conduit size and installation direction.
Switch and Socket Boxes
Where conduit runs terminate at switch or socket positions, metal or PVC back boxes are used to house the accessory. These boxes have threaded or knock-out entries that accept conduit entry fittings, maintaining the integrity of the enclosed system right to the point of the electrical accessory.
Common Mistakes in Conduit Installation
Understanding what goes wrong helps in avoiding these issues from the outset.
- Undersizing the conduit: This is the most common problem. When a conduit is too small for the cables being installed, pulling becomes extremely difficult, cable sheaths are damaged during installation, and the installation may not be compliant. Size the conduit based on actual cable diameters and the appropriate space factor, not by estimation.
- Too many bends between draw-in points: Each bend in a conduit run multiplies the pulling force required to draw cables through it. Runs with more than four equivalent right-angle bends between draw-in points become impractical to cable and risk cable damage. Position junction boxes at appropriate intervals to keep the number of bends between pull points manageable.
- Using PVC conduit in mechanically hazardous locations: PVC is not suitable where there is a realistic risk of physical impact. In industrial environments, service corridors, loading areas, or anywhere that vehicles or heavy equipment operate near the cable route, steel conduit is the correct specification.
- Skipping cable pulling lubricant: Pulling cables through a conduit without lubricant is much harder and creates a real risk of sheath damage. The sheath damage may not be obvious after installation but creates a weak point that will fail in service.
- Not maintaining earth continuity in steel conduit: Poorly made conduit joints break the earth continuity of the steel conduit system. This must be tested during and after installation. A steel conduit system without confirmed earth continuity is not compliant and is not safe.
- Using the wrong conduit for the environment: Standard indoor PVC conduit in an outdoor UV-exposed location will degrade and become brittle. Standard GI conduit in a highly corrosive environment will corrode through faster than expected. Always match the conduit specification to the actual conditions it will face.
- Not planning for future access: Conduit that is installed without adequate junction boxes or draw points makes future cable replacement extremely difficult. It is much cheaper to install the right number of access points during initial installation than to retrofit them later.
Frequently Asked Questions
1. What is the difference between GI conduit and EMT conduit?
GI conduit (galvanised iron / steel conduit) is a heavy-wall threaded conduit manufactured to BS4568 or IEC61386. EMT (Electrical Metallic Tubing) is a thinner-wall conduit used primarily in North American electrical practice that uses compression fittings rather than threaded joints. In the UK and most of Europe, GI conduit to the relevant British and IEC standards is the standard specification for steel conduit systems.
2. Can I use PVC conduit outdoors?
Standard grey PVC conduit has limited UV resistance and will become brittle and discoloured over time if exposed to direct sunlight. For outdoor use where the conduit is exposed to UV, specify UV-stabilised black PVC conduit, which is compounded to resist UV degradation. For outdoor locations with significant mechanical risk, GI conduit is the more robust specification.
3. How many cables can I put in a conduit?
The number of cables that can be installed in a conduit is governed by the space factor rule: the cables collectively should not occupy more than 40% of the conduit internal cross-sectional area on a straight run. The actual number depends on the outer diameter of the specific cables being used. Conduit sizing tables in BS 7671 and from conduit manufacturers provide practical guidance for common cable combinations.
4. Does conduit need to be earthed?
Steel conduit systems must be earthed because the conduit is a metallic structure that could become live if a fault occurred inside it. The earth continuity of the conduit is verified with a continuity test during installation. PVC conduit does not conduct electricity and does not need to be earthed as part of the earthing system, though cables inside it still require an earth conductor as part of the circuit.
5. When should I use flexible conduit instead of rigid?
Flexible conduit is used where rigid conduit cannot follow the required route without an excessive number of fittings, where the conduit needs to connect to equipment that vibrates, where the equipment connection point may need to be repositioned, or where a flexible final section is needed between a rigid conduit run and the equipment entry point. Flexible conduit is not a substitute for rigid conduit on fixed cable routes: it is a solution for the specific situations where rigid conduit is impractical.
6. What is the maximum conduit run length between draw points?
There is no fixed maximum length, but as a practical guide, the IET Wiring Regulations recommend that the total pulling resistance of a run should be manageable with the cable pulling equipment being used and without risking damage to the cables. For standard installations, this generally means runs should not exceed around 15 to 20 metres between draw points on a straight run, with this distance reducing for each bend in the run.
Choosing the Right Cable Conduit for Safe & Reliable Installations
Cable conduits are a fundamental part of electrical installation practice, and selecting the right type matters for the safety, longevity, and maintainability of the installation. GI conduit delivers mechanical strength, fire resistance, and earthing continuity for demanding environments. PVC conduit provides a practical, corrosion-resistant solution for standard domestic and commercial installations. Flexible conduit bridges the gap between rigid systems and moving or vibrating equipment.
The selection process is straightforward when you work through the environmental conditions, the circuit requirements, the cable types being installed, and the practical constraints of the installation. Getting these decisions right at the specification stage avoids expensive remedial work and ensures the installation performs reliably throughout its service life.
For anyone specifying or installing a complete cable management system, conduit works alongside a range of other components. The guides on cable glands, cable cleats, cable ties, and cable pulling lubricants cover the other elements of a complete installation. And for the cables themselves, the guides to H07RN-F rubber cables and signal cables explained provide the same level of practical detail for the cables that run inside the conduit systems covered here.