PVC vs. Metal Cable Trunking: A Practical Comparison for Installers

What Cable Trunking Is and Why Material Choice Matters

Cable trunking is a rigid, usually rectangular enclosure with a removable lid, used to route and protect multiple cables along walls, ceilings, or floors in commercial, industrial, and residential buildings. Unlike conduit, trunking is designed for easy access, allowing installers to add, remove, or reroute cables without pulling them through a closed tube.

The material the trunking is made from affects far more than appearance. It determines fire behavior, mechanical strength, electromagnetic shielding, corrosion resistance, and installation labor time, all of which directly affect both project cost and code compliance. Choosing the wrong material for the environment is one of the most common reasons trunking installations fail inspection or require costly rework.

PVC Cable Trunking: Strengths and Limitations

Strengths

PVC trunking is lightweight, non-conductive, and resistant to corrosion, making it well suited to damp or humid environments where metal would eventually rust. It requires no grounding or bonding, which simplifies installation and reduces labor time. PVC trunking typically costs 30-50% less than equivalent metal trunking, making it the default choice for budget-conscious commercial and residential jobs where fire rating isn't a code requirement.

Limitations

Standard PVC trunking offers no electromagnetic shielding, so it isn't suitable for routing sensitive data or signal cables near sources of electrical interference. It also softens and can deform at elevated temperatures, generally becoming unsuitable above 60°C continuous exposure, and provides no fire-resistance rating on its own, meaning it typically cannot be used in designated fire escape routes without specialized fire-rated PVC products.

Metal Cable Trunking: Strengths and Limitations

Strengths

Metal trunking, typically galvanized or powder-coated steel, offers significantly higher mechanical strength and impact resistance than PVC, making it the standard choice in industrial environments where physical damage risk is higher. It provides natural electromagnetic shielding, protecting sensitive data and control cables from interference, and can be specified with fire-resistance ratings suitable for use in fire escape corridors and plant rooms. Steel trunking can typically withstand continuous operating temperatures well above 100°C, far exceeding PVC's practical limit.

Limitations

Being conductive, metal trunking must be properly grounded and bonded as part of the electrical installation, adding both material cost and labor time. It's heavier, requiring more robust mounting hardware, and is more susceptible to corrosion in damp or coastal environments unless specifically rated for those conditions (such as hot-dip galvanized or stainless steel variants).

Side-by-Side Comparison

The table below summarizes the key practical differences installers weigh when specifying trunking material for a job.

When to Choose PVC Trunking

• Standard office, retail, or residential installations with no elevated fire-rating requirement.
• Bathrooms, kitchens, or other damp locations where corrosion resistance matters more than mechanical strength.
• Budget-sensitive projects where minimizing material and labor cost is a priority.
• Low-risk areas where mechanical damage from impact or vandalism is unlikely.
• Retrofit projects where lightweight material simplifies mounting on existing walls or ceilings.

When to Choose Metal Trunking

• Fire escape routes, stairwells, and plant rooms where local fire codes require fire-rated cable containment.
• Industrial facilities, warehouses, or workshops where impact from equipment or material handling is a realistic risk.
• Data centers or areas routing sensitive control and communication cabling near sources of electromagnetic interference.
• High-temperature environments, such as near boiler rooms or industrial process equipment.
• Public or high-security areas where tamper resistance and long-term durability outweigh upfront cost.

Standards and Compliance Considerations

Both PVC and metal trunking products intended for professional electrical installation are generally manufactured to comply with BS EN 50085 (cable trunking and ducting systems) in the UK and Europe, or equivalent national electrical codes elsewhere. Installers should verify that any fire-rated product carries documented test certification (such as BS 476 fire testing) rather than relying on material type alone as a guarantee of fire performance.

Metal trunking installations must also comply with local grounding and bonding regulations, since an inadequately bonded metal enclosure can itself become an electrical hazard rather than a protective measure. Continuity testing of the bonding connection is a standard requirement during inspection and certification of metal trunking runs.

Practical Installation Tips

1. Confirm the fire-rating and code requirement for the specific area before selecting material, rather than defaulting to habit or availability.
2. When using metal trunking, plan and price bonding and grounding connections into the job from the start, not as an afterthought.
3. Size trunking capacity with room for future cable additions; a general guideline is filling no more than 45% of the internal cross-sectional area to allow for heat dissipation and future expansion.
4. In mixed environments, consider using metal trunking for exposed, high-risk runs and PVC for protected, low-risk sections to balance cost and protection.
5. Always request manufacturer test certificates for fire-rated products rather than assuming compliance based on material alone.

Neither PVC nor metal trunking is universally "better" — each is the right tool for a different risk profile. PVC delivers lower cost, faster installation, and strong corrosion resistance for standard indoor environments, while metal delivers fire resistance, mechanical protection, and EMI shielding for demanding or code-restricted installations. Installers who match the material to the specific fire, environmental, and mechanical demands of each area — rather than defaulting to one material across an entire project — will avoid costly rework and deliver installations that pass inspection the first time.