Selection Guide
Conduit Selection Guide — Flexible, Rigid, Metallic & Non-Metallic
Complete conduit selection guide: flexible vs rigid, metallic vs non-metallic, PVC, galvanized steel, liquid-tight, and corrugated conduit comparison.
Overview
Conduit protects cables from mechanical damage, moisture, chemicals, and fire. This guide covers all conduit types and provides selection criteria based on installation environment and cable protection requirements.
Selection Process
Assess Mechanical Protection Needs
Light protection (indoor, accessible): corrugated or flexible. Medium (outdoor, industrial): rigid PVC or EMT. Heavy (vehicle traffic, impact): rigid steel (RMC/IMC).
Evaluate Environmental Conditions
Wet/damp: liquid-tight flexible or PVC. Corrosive: PVC or stainless steel. High-temp: steel or high-temp rated. UV outdoor: UV-stabilized PVC or steel.
Consider Installation Method
New build with open access: rigid conduit. Retrofit or tight spaces: flexible conduit. Underground: PVC or HDPE. Plenum: metallic only (NEC 300.22).
Check Fire Rating Requirements
Plenum spaces: metallic only. Riser: metallic or fire-rated non-metallic. General: check local code. EN 45545-2 for railway. Marine: IEC 60092.
Select Size
Fill capacity: typically 40% max for 3+ conductors, 53% for single conductor. Use conduit fill calculators. Allow for future cable additions.
Frequently Asked Questions
What conduit type for underground installation?
PVC Schedule 40 or 80 (concrete-encased or direct burial), or HDPE for longer runs. Metallic conduit underground requires corrosion protection (PVC-coated or stainless steel). Always check local code for burial depth requirements.
When should I use liquid-tight flexible conduit?
Outdoor equipment connections (motors, pumps), areas subject to washdown, connections requiring vibration isolation, and where rigid conduit cannot accommodate equipment movement or thermal expansion.
Need Application-Specific Advice?
Our engineers can help you select the right product for your exact requirements.