Do Fiber-Optic Cables Need to Be Grounded?

Do Fiber Optic Cables Need to Be Grounded?

While nonarmored fiber optic cables don't require grounding due to their nonconductive properties, grounding is crucial when using armored fiber optic cables. These cables include metallic components that can carry electrical currents, presenting potential hazards such as electrical shock or fire risks if left ungrounded.

Understanding fiber optic cable grounding requirements is essential for protecting your network infrastructure, preventing downtime and maintaining safety on the jobsite. Let's explore how fiber optic systems work, when grounding is required and how to do it correctly.

Understanding Fiber Optic Technology Basics

Fiber optic cables consist of thin strands of fused silica (SiO₂) that transmit data as light signals, providing faster speeds and greater bandwidth than traditional copper cables, which transmit data via electrical signals. Fiber optics operate by sending light pulses through the core of the fiber. The core is surrounded by cladding made of the same material but with a different refractive index. This structure keeps light bouncing back and forth in a zig-zag configuration within the core for efficient transmission. This process is known as total internal reflection.

Unlike copper wires, fiber optic cables can maintain higher data integrity over longer distances and under harsh electromagnetic interference (EMI) conditions. This technology also enhances security since bad actors cannot easily tap data transmitted as light.

Armored vs. Nonarmored Fiber Optic Cable Options

Fiber optic cables fall into two main categories — armored and nonarmored. Both serve distinct roles depending on the installation environment.

Nonarmored Fiber Optic Cables

Nonarmored cables feature a protective jacket but no metal components. They are ideal in installations where physical protection isn't a significant concern. These cables are lightweight and flexible, making them easier to install, especially in tight or complex pathways. The absence of a metallic protective outer layer makes fiber cables more cost-effective. However, they require additional protection, such as conduits, in environments where physical damage or tampering is possible.

Since dielectric fiber optic cables are immune to electrical hazards, they are popular for overhead use or in areas exposed to lightning or electrical interference. A good example is an all-dielectric self-supporting (ADSS) cable. Built entirely from nonconductive materials, ADSS is ideal for aerial installations, offering structural integrity without the need for support wires or grounding.

Armored Fiber Optic Cables

In contrast, armored fiber optic cables feature a steel or aluminum jacket that protects the inner glass fibers from damage. These jackets offer mechanical durability in harsh environments, such as underground or industrial installations, where cables may be susceptible to damage by rodents, construction debris or crushing forces. Armored fiber optic cable grounding is critical because the metal layer can conduct electricity if exposed to lightning strikes or nearby electrical systems.

Armored vs. Nonarmored Fiber Optic Cables

Grounding Requirements: When Is It Necessary?

As we have established, nonarmored or dielectric fiber optic cables do not require grounding because they contain no conductive components. Their dielectric properties provide natural immunity to electromagnetic interference and lightning-induced currents.

In contrast, grounding armored fiber optic cables is mandatory. Proper grounding helps dissipate any stray electrical current, ensuring that it doesn't pose safety hazards, including shock risks to personnel and potential damage to equipment. Grounding also helps prevent the buildup of static electricity that can cause malfunctions in sensitive network equipment or disrupt the signal integrity of the fiber optic cable by attracting dust and contaminants on the end faces.

National Electric Code (NEC) Guidelines

NEC provides comprehensive guidelines for the grounding of armored fiber optic cables. Specifically, NEC Article 770.93(A) and (B) and 770.100(A) through (D) outline the grounding and bonding requirements for cables with non-current-carrying metallic components, such as those found in armored fiber optic cables.

NEC Article 770.93(A) requires technicians to ground any fiber optic cable at the point of entry to a building. NEC Article 770.93(B) requires service personnel to connect the grounding connection to a reliable and continuous path to the earth or an equivalent grounding system that provides a low-resistance path to dissipate electrical currents safely.

These codes also distinguish between grounding requirements for cables at the building entrance and exterior terminations. For cables entering a building, technicians must connect the bonding or grounding electrode conductor to the building's grounding electrode system. Exterior termination points also require proper bonding to grounding electrodes or an interruption by an insulating joint or equivalent device.

How to Properly Ground Armored Fiber Optic Cables

To complete a reliable grounding connection, you'll need:

• Grounding clamps
• 6 AWG copper grounding wires
• Ground bar or grounding bus
• Vinyl tape
• Fiber optic strippers

Here's a brief step-by-step fiber optic cable grounding guide:

1. Expose the armor: Expose at least 1 inch of the metallic section of the armored cable by carefully stripping back the outer jacket using a fiber optic stripper.
2. Attach a metal clamp: Use an appropriate metal clamp to bite into the armor and create a secure bond.
3. Connect to the ground bar: Run a UL-listed 6 AWG copper conductor straight from the clamp's grounding post to a grounding system. The grounding electrode conductor should be as short as possible and no more than 6 meters.
4. Tape and secure the connection: Wrap the clamp and exposed metal with electrical tape to securely hold everything and prevent moisture ingress and sharp edges from damaging the jacket.
5. Verify continuity: Measure resistance between the armor and the grounding bar to confirm a low-ohm path.

Proper fiber optic bonding is also critical to ensure that all metallic components are interconnected before they're grounded. In addition to using the right tools, technicians should avoid common mistakes like improper clamp placement, loose connections, grounding to unapproved surfaces or using undersized wires.

Best Practices for Fiber Optic Installation Safety

Successful fiber optic cable installation requires adherence to strict safety protocols to protect personnel and equipment.

• Personal protective equipment (PPE) recommendations: Technicians should use proper PPE, including cut-resistant gloves, safety glasses and arc-flash–rated clothing, when handling fiber optic cables and performing grounding tasks.
• Tool requirements for safe installation: To improve installation quality and safety, use specialized tools such as fiber cleavers, fusion splicers and grounding clamps. Cable handling also requires attention to minimum bend radii, pulling tensions and protection against sharp edges.
• Environmental considerations: Environmental conditions also impact safety. Installers must maintain safe clearance distances and coordinate with utility providers when working near electrical power lines. Underground installations need careful excavation, pathway preparation and adherence to local regulations.
• Building entrance precautions: Take special care at the point where the fiber optic cable enters a building, including proper grounding and bonding as per NEC 770.100. Documenting and labeling grounding points also facilitates future maintenance and troubleshooting.
• Industry standards and certification requirements: All installations should adhere to relevant telecommunications installation standards, such as ANSI-J-STD-607 Commercial Building Grounding and Bonding Requirements for Telecommunications. Service personnel should also follow grounding and bonding best practices from the BICSI Telecommunications Distribution Methods Manual (TDMM).

Reliable and Compliant Fiber Optic Cable Grounding With Multilink

Fiber optic networks are the foundation of modern communication. While nonarmored fiber optic cables don't need grounding due to their dielectric properties, armored fiber optic cables feature metallic components that must be earthed appropriately to maintain safety and performance. Grounding fiber optic cables protects against electrical hazards, static buildup and lightning strikes, minimizing risks to personnel, equipment and infrastructure.

Multilink is an ISO 9001-certified company with decades of expertise in telecommunications infrastructure. We supply reliable products and expert services tailored to your needs. Our team understands the technical nuances of grounding and bonding armored fiber optic cables and supports you with solutions that optimize installation efficiency and meet code compliance.

We handle design, manufacturing and field service under one roof, ensuring seamless compliance and performance. Contact Multilink today for expert guidance or to schedule a consultation to integrate safe, durable grounding into your next fiber deployment.