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250.94(A) and (B) Bonding for Communication Systems

Revision and New

Change Summary

  • The title of this section was renamed “Bonding for Communication Systems” and a new 250.94(B) was added titled “Other Means” allowing an alternate connection option to be made on a common bus bar. A new exception was added for 250.94(A) and (B) offering relief from an intersystem bonding connection means “where communications systems are not likely to be used.”
NEC® Text

250.94 Bonding for Other Communication Systems.
Communications system bonding terminations shall be connected in accordance with (A) or (B).
(A) The Intersystem Bonding Termination Device.
An intersystem bonding termination (IBT) for connecting intersystem bonding conductors required for other systems shall be provided external to enclosures at the service equipment or metering equipment enclosure and at the disconnecting means for any additional buildings or structures. The intersystem bonding termination If an IBT is used, it shall comply with the following:

(Remainder of 250.94(A) unchanged. See NEC for complete text.)

(B) Other Means. Connections to an aluminum or copper busbar not less than 6 mm thick × 50 mm wide (¼ in. thick × 2 in. wide) and of sufficient length to accommodate at least three terminations for communication systems in addition to other connections. The busbar shall be securely fastened and shall be installed in an accessible location. Connections shall be made by a listed connector. If aluminum busbars are used, the installation shall also comply with 250.64(A).

Exception to (A) and (B): Means for connecting intersystem bonding conductors are not required where communications systems are not likely to be used.

Informational Note: The use of an IBT can reduce electrical noise on communication systems.

Copyright© 2016 National Fire Protection Association
(See NEC for complete text)

Expert Analysis

Bonding for Other Communications Systems

The title of the section was changed to “Bonding for Communication Systems.” The existing text for the intersystem bonding termination was placed under List Item (A) and titled, “The Intersystem Bonding Termination Device.” The six conditions that must be met to qualify as an intersystem bonding termination have not changed, and the one exception for existing buildings or structures remains the same. Intersystem bonding — which is accomplished by connection of a communication grounding conductor to the power system grounding electrode system — is an important safety measure to prevent differing voltage potential between the communication system and the power system. The intersystem bonding termination is for bonding of intersystem bonding conductors only.

A new 250.94(B) was added titled, “Other Means,” which permits intersystem bonding connections to an aluminum or copper busbar that will accommodate at least three terminations for communication systems as well as “other connections.” This method is often used in commercial or multifamily mixed-use buildings. Even though the previous language was not restricted to just dwelling units and worked well for a dwelling unit, it did not take into account how a commercial or industrial building may bond the communication systems and other systems. Many commercial buildings commonly utilize a common grounding terminal bar for the connection of multiple electrodes and bonding of other systems, such as water piping systems, building steel, and internal antenna systems — to name a few. This new “other means” of terminating other systems allows the installer to terminate other bonding conductors for bonding all systems, including such things as corrugated stainless steel tubing (CSST) gas piping, which is still prohibited to be terminated on the intersystem bonding termination device.

A new exception to 250.94(A) and (B) was also added to give relief from providing a means for connecting intersystem bonding conductors where communications systems are not likely to be used. This exception would include such things as outhouses, chicken coops or garden sheds.

Bonding for Other Communications Systems

250.94(B) Other Means

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