Bonding and Grounding Armored Fiber Cable

Feb 18, 2022

Why Bond and Ground?

For the safe and effective dissipation of undesired electrical current, proper grounding and bonding is essential, as well as for personal and site safety. Although fiber-optic systems do not often carry electrical power, the metallic components of a conductive cable can carry current. If a metallic component of the cable, such as the interlocking or corrugated armor, came into touch or was in close proximity to electrical current from sources such as exposed wiring, malfunctioning electrical systems, lightning, or other events, this would happen. This increases a variety of risks, including electrical shock, fire, electronic damage, and system malfunctions that result in downtime.

Armored fiber-optic cable bonding and grounding are simple phases in the installation process but are sometimes misunderstood or omitted. To promote safe and effective bonding and grounding methods of armored optical cables, the National Electrical Code (NEC) and many industry standards have been established. Local area networks (LANs) have traditionally relied on ANSI/TIA-568-C.0 Generic Telecommunications Cabling for Customer Premises, ANSI/TIA-569-B Commercial Building Standard for Telecommunications Pathways and Spaces, and ANSI-J-STD-607 Commercial Building Grounding (Earthing) and Bonding Requirements for Telecommunications for additional guidance, in addition to the NEC. The ANSI/TIA/EIA-942 Telecommunications Infrastructure Standard for Data Centers has also been used by data centers.

The Institute of Electrical and Electronics Engineers (IEEE) has released documents on bonding and grounding best practices, as well as the BICSI Telecommunications Distribution Methods Manual (TDMM). Furthermore, a location’s grounding and bonding codes may differ from the current edition of the NEC and industry standards. With specific questions about compliance, it is recommended that you consult the local authority within your jurisdiction.

A fiber-optic cable including non-current-carrying metallic components, such as armor or metallic strength members, is deemed conductive, according to NEC Article 770. This is why, according to NEC Article 770.100, conductive fiber-optic cables must be joined and grounded.


How to Bond and Ground

To begin, it’s critical to comprehend the distinction between the terms bonding and grounding. Bonding, according to the NEC and industry standards, is the permanent connecting of metallic pieces to provide a conductive and continuous electrical route. The act of connecting that channel to the earth or a conducting body that acts as the earth is known as grounding. The risk of electrical current hurting employees or destroying property and equipment is lowered when all components of a system are correctly connected together and grounded to the earth.

The cable armor must first be connected/bonded to a bonding or grounding electrode conductor. This can be done immediately after the cable has been accessible and the armor has been exposed. A bonding conductor, also known as a jumper, is a small piece of copper wire that maintains electrical conductivity between two metal objects. The bonding conductor must be UL-listed and constructed of copper or another corrosion-resistant conductive metal. The wire, whether stranded or solid, can be insulated, coated, or left bare. Most cable manufacturers include a 6-AWG copper strand that is insulated and UL-listed.

For the bonding conductor, the 6-AWG size is preferred because it complies with both the NEC and ANSI-J-STD-607. According to NEC

Article 250.70, the bonding conductor can be joined to the armor with a designated clamp, lug, or connector.

Vinyl tape can be put around the clamp and exposed armor to protect the installer and the fiber from any sharp edges where the armor is exposed after it has been attached.

The bonding conductor from the conductive fiber-optic cable must be attached to the intersystem bonding termination (if existent) or another accessible point per NEC Article 770.100 for the cable to be fully grounded. The device that connects the bonding conductors to the building’s grounding electrode and, ultimately, to earth is known as the intersystem bonding termination. The bonding conductor is typically connected to a dedicated channel back to the telecoms main grounding busbar (TMGB) or the telecommunications grounding busbar (TGB).

The dedicated path can be a direct run or generated by connecting to the bonding system of a rack or cabinet, which connects the rack or cabinet to the TMGB or TGB.

ANSI-J-STD-607 and other industry standards contain specific specifications for the design of the TMGB or TGB. When the armored cable is properly bonded and grounded, the risk of undesired electrical current harming workers, property, or equipment is reduced.