Wednesday, July 13, 2011


The ANSI/TIA-607-B Commercial Building Grounding and Bonding Requirements for Telecommunications Standard covers grounding and bonding to support a telecommunications system. This document should be used in concert with Article 250 and Article 800 of the NEC. ANSI/TIA-607-B does not cover building grounding; it only covers the grounding of telecommunications systems.
ANSI/TIA-607-B specifies that the telecommunications ground must tie in with the building ground. Each telecommunications room must have a telecommunications grounding system, which commonly consists of a telecommunications bus bar tied back to the building grounding system. All shielded cables, racks, and other metallic components should be tied into this bus bar.
ANSI/TIA-607-B specifies that the minimum ground-wire size must 6 AWG, but, depending on the distance that the ground wire must cover, it may be up to 3/0 AWG (a pretty large copper wire!). Ground-wire sizing is based on the distance that the ground wire must travel; the farther the distance, the larger the wire must be. ANSI/TIA-607-B supplements (and is supplemented by) the NEC. For example, Article 800-100 specifies that telecommunications cables entering a building must be grounded as near as possible to the point at which they enter the building.
When protecting a system with building ground, don't overlook the need for lightning protection. Network and telephone components are often destroyed by a lightning strike. Make sure your grounding system is compliant with the NEC.
Grounding is one of the most commonly overlooked components during the installation of a structured cabling system. An improperly grounded communications system, although supporting low-voltage applications, can result in, well, a shocking experience. Time after time we have heard stories of improperly grounded (or ungrounded) telecommunications cabling systems that have generated mild electrical or throw-you-off-your-feet shocks; they have even resulted in some deaths.
Grounding is not to be undertaken by the do-it-yourselfer or an occasional cable installer. A professional electrician must be involved. He or she will know the best practices to follow, where to ground components, which components to ground, and the correct equipment to be used. Further, electricians must be involved when a telecommunications bus bar is tied into the main building ground system.
Grounding to a water pipe may not provide you with sufficient grounding, as many water systems now tie in to PVC-based (plastic) pipes. It may also violate NEC and local-code requirements.

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