What is conduit
Conduit is the protective tubing through which electrical cables are routed in buildings, plants and outdoor installations. It shields cables from mechanical damage, UV exposure, water, dust, rodents and fire. For solar PV installations, conduit serves dual purposes: physical protection of the cable run and code compliance with IS 732 wiring code and CEA Measures Relating to Safety.
Indian solar installations use rigid PVC conduit for most cable runs, flexible PVC for short connections to equipment, GI (galvanised iron) for industrial environments and HDPE for buried installations. Selection depends on environment, cable types and mechanical requirements.
Why conduit matters
Cable protection. Prevents physical damage and rodent attack.
UV shielding. Protects standard cables from sunlight degradation.
Code compliance. Required by IS 732 for certain installation methods.
Aesthetic. Tidy installation without exposed cables.
Future flexibility. Cables can be drawn out and replaced.
Fire safety. Some conduit types provide fire containment.
Conduit types
| Type | Material | Use |
|---|---|---|
| Rigid PVC | uPVC | Indoor and short outdoor |
| Flexible PVC | PVC | Short connections to enclosures |
| GI (galvanised iron) | Steel | Industrial, fire-rated |
| Flexible GI | Steel | Industrial machine connections |
| HDPE | Polyethylene | Underground, chemically aggressive |
| Stainless steel | SS | Marine, highly corrosive |
| MS painted | Steel | Cost-sensitive indoor |
Technical deep dive
Common sizes (Indian)
| Size (mm) | Internal diameter | Cables (approximate) |
|---|---|---|
| 16 | ~13 | 2-3 small |
| 20 | ~16 | 3-4 small |
| 25 | ~21 | 4-6 medium |
| 32 | ~28 | 6-8 medium |
| 40 | ~35 | Several large |
| 50 | ~44 | DC trunk |
| 100 | ~92 | Utility trunk |
Fill ratio
| Number of cables | Maximum fill ratio |
|---|---|
| 1 | 53% |
| 2 | 31% |
| 3+ | 40% |
Beyond fill ratio causes cable heating and reduces ampacity.
IP rating for outdoor
| Component | Required IP |
|---|---|
| Conduit + glands | IP65 |
| Junction box | IP65 |
| Combiner box | IP65 or IP66 |
Bonding
Real-world applications
Rooftop residential solar DC and AC runs, the same scope covered in our timeline for how long solar installation takes in India.
Roof-to-inverter cable routing.
Inverter-to-distribution-board AC runs.
Utility ground-mount cable trenches, planned as part of ground-mount design engineering.
Carport DC routing.
Floating solar conduit through floating platforms.
Common conduit problems
UV degradation in non-UV-rated PVC.
Heat damage near hot inverters.
Water ingress through inadequate seals.
Rodent damage to thin-walled conduit.
Sharp internal edges damaging cable insulation.
Inadequate bend radius causing cable stress.
Best practices
Use UV-stabilised PVC for outdoor runs.
GI in fire-sensitive or industrial environments.
Maintain fill ratio under 40 percent.
Use cable glands rated IP65 at all entries.
Apply sealant at junction box entries.
Bond GI conduit to earth.
Document conduit routes on the single line diagram.
Use proper deburring tools on cut ends.
Comparison: conduit types
| Type | Cost | UV | Mechanical | Use |
|---|---|---|---|---|
| Rigid PVC | Low | Good if UV-stable | Good | Standard |
| Flexible PVC | Low | Moderate | Moderate | Short runs |
| GI | Medium | Excellent | Excellent | Industrial |
| HDPE | Medium | Excellent | Excellent | Buried |
| Stainless | Highest | Excellent | Excellent | Marine |
Indian market context
Major Indian conduit brands: Polycab, Anchor, Schneider, Anchor Roma, Havells, Finolex, Honeywell Press-on.
ALMM does not list conduits. BIS certification under IS 9537 (PVC) and related standards.
PM Surya Ghar residential installations use 20 to 32 mm UV-rated PVC conduit.
C&I rooftops use combination of rigid PVC for cable runs and flexible PVC for equipment connections — routing decisions that EPCs typically evaluate during solar EPC bid evaluation.
Utility plants use HDPE for buried runs and GI or PVC overhead, often specified as part of turnkey solar EPC installation scope.
Standards and certifications
| Standard | Scope |
|---|---|
| IS 9537 | PVC conduits |
| IS 14930 | Flexible conduit |
| IEC 61386 | International conduit standard |
| IS 732 | Wiring code, conduit installation |
| CEA Measures Relating to Safety 2023 | Indian safety |
Common mistakes
Using non-UV-rated PVC outdoors.
Exceeding fill ratio.
Inadequate IP-rated cable glands at entries.
Skipping conduit on long DC runs through hot sun.
Wrong conduit material for environment.
Sharp internal edges from poor cutting.
Failing to bond GI conduit.
Key takeaways
Conduit protects and routes electrical cables in solar installations. Indian standards (IS 9537, IS 14930, IS 732) govern PVC, flexible and GI conduit selection. Rigid PVC dominates rooftop installations; HDPE underground; GI in industrial. Maintaining fill ratio, IP-rated cable glands and proper bonding ensures 25-year cable protection. Documentation on SLD enables future maintenance.
Further reading
For how Conduit plays out in real projects, these guides go deeper:
- Solar System Annual Maintenance Checklist India
- Pre-Monsoon Solar System Inspection Checklist India
- Solar Inverter Installation Cost, Real Numbers
- Solar Takeoff Software: Auto-BOQ Guide 2026
Sources
- IS 9537, PVC conduits for electrical installations.
- IS 14930, Flexible conduit.
- IEC 61386 series, Conduit systems for cable management.
- IS 732, Indian wiring code.
- CEA Measures Relating to Safety and Electric Supply Regulations 2023.
- Manufacturer documentation from Polycab, Anchor, Schneider, Havells, Finolex.
- CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations, 2013 (as amended 2019), Central Electricity Authority.
- IEC 60529, IP ratings.
- IEC 62548, PV array design.
Frequently Asked Questions
What is conduit in simple words?
What conduit types are used in solar?
Why is conduit needed?
What conduit size?
Is conduit mandatory for solar DC?
How is conduit installed?
What is conduit fill ratio?
Can conduit run outdoors?
Are flexible conduits suitable for solar?
What is the typical cost?
How are conduits sealed at entries?
Can conduit damage from heat?
What is HDPE conduit?
Are GI conduits earthed?
Is conduit reusable?
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Co-founder & CEO driving Qbits Energy's product strategy and growth across India.