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This article was posted 04/14/2006 and is most likely outdated.

Grounding vs Bonding: 250.94 Grounding (Bonding) of Communications Systems

April 14, 2006

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PART V. BONDING

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250.94 Grounding (Bonding) of Communications Systems.

An accessible bonding point must be provided at service equipment or the disconnecting means of separate buildings or structures for communications systems. The point can be any one of the following:

(1) An exposed, nonflexible metallic raceway.
(2) An exposed grounding electrode conductor.
(3) An external connection approved by the authority having jurisdiction.

FPN No. 2: Communications systems must be bonded together. Figure 250–134

• Antennas/Satellite Dishes, 810.21
• CATV, 820.100
• Telephone Circuits, 800.100

Author’s Comment: The bonding of all external communications systems to a single point minimizes the possibility of damage to the systems from potential (voltage) differences between the systems. Figure 250–135

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Figure 250–134
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Figure 250–135
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Comments

Mike, Your Diagram 250-135 shows bonding between all communications devices and the electrical ground. In some cases, that is accomplished through the grounding pin on the electrical plug.

However, it is not clear how it is accomplished on devices that do not have a direct electrical connection. For example, Telcos are starting to bring services into homes over fiber, and are asking for an electrical ground where the fiber termination unit connects to telephone, data, and video cabling.

They are asking for a #10 ground wire from a nearby electrical outlet to be available on the surface of an inside wall for connection to a ground lug on their surface-mounted box.

Is there a Code-compliant way to bring a grounding (bonding) wire out of an existing electrical box? (particularly if it is a "decora" style outlet with no center screw)

Can a ground wire be run from the wall surface into the wall, through a hole or a low-voltage ring, and bonded to an electrical box?

Thank you!

Orrin Charm InfiniSys

Orrin Charm

Reply from: Mike Holt
Communications system must be grounded in accordance with the NEC, and your suggested installation of grounding to an outlet box is not one of the methods permitted by the NEC. See 800.100.

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