Why Liners Matter in Cable Cleats and Cable Straps

When it comes to electrical installations, every detail counts. One often-overlooked detail is the use of liners in cable cleats and cable straps. Liners are protective layers, usually made of polymer or elastomer, that sit between the cable and the cleat or strap. Their purpose is simple yet critical: to protect the cable’s outer sheath from mechanical damage. Unfortunately, liners are sometimes omitted in the name of cost-cutting or convenience. This can lead to serious consequences, including system failures and safety hazards. Let’s explore why liners are so important and what can happen if they’re not used when necessary.

The Role of Liners

Cables are designed to carry electrical energy safely, but their outer sheath is not indestructible. When a cable is secured with a metal cleat or strap without a liner, the hard surface can press directly against the sheath. Over time, or under fault conditions, this pressure can cause abrasion, indentation, or even cutting through the sheath.

Liners act as a cushion, distributing pressure evenly. They also help maintain the integrity of the cable during thermal expansion and contraction cycles.

What Happens Without Liners?

The absence of liners can lead to several issues:

1. Sheath Damage and Ground Faults
   One of the most serious risks is the strap or cleat cutting through the cable’s outer sheath. If the damage reaches the conductor or screen, it can create a ground fault. Ground faults not only disrupt operations but can also pose fire and shock hazards.

2. Accelerated Cable Wear
   Even if the sheath isn’t completely breached, constant pressure and vibration can weaken it over time. This reduces the cable’s lifespan and increases maintenance costs.

3. Non-Compliance with Standards
   Many industry standards, including IEC 61914 for cable cleats, emphasise mechanical protection. Omitting liners where required can result in non-compliance, exposing the installer and sign-off authority to liability.

4. System Reliability Risks
   Damaged cables can lead to unexpected outages, costly downtime, and reputational damage for contractors and facility owners.

Best Practices

• Follow Manufacturer Guidelines: If the cleat or strap design includes a liner, never remove it.

• Consider Cable Type: Single-core cables, high-voltage cables, and cables with softer sheaths are particularly vulnerable.

• Inspect During Installation: Ensure liners are properly seated and not displaced during tightening.

• Document Compliance: Keep records showing that liners were used as specified.

Conclusion

Liners may seem like a minor detail, but their role in protecting cables is critical. Omitting them can lead to sheath damage, ground faults, and costly failures. By ensuring liners are used where necessary, installers and engineers uphold safety, compliance, and system reliability. In electrical installations, small components often make the biggest difference - liners are a perfect example.

Further reading:

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