Appendix B Rule 10-616
The principal purpose of a bonding conductor is to provide a low impedance path for fault current and facilitate the operation of overcurrent protective devices, in addition to serving as an equipotential bonding connection.
Rule 10-616 1) and 3) a)
When the system or circuit conductors on the secondary side of a transformer are protected only by the overcurrent devices on the primary side, the voltage ratio of the transformer is applied to the overcurrent device rating in applying Column 1 of Table 16.
Rule 10-616 3) b)
When the size of a circuit conductor is increased to compensate for voltage drop due to circuit length, the ampacity of that conductor exceeds that required for the connected load and the rating of the overcurrent protective device. The bonding conductor needs to be increased proportionately to minimize the impedance of the bonding path and facilitate the operation of the overcurrent device. The size of the bonding conductor is based on the circuit conductor allowable ampacity given in Column 2 of Table 16 to compensate for conductor length.
Rule 10-616 4)
When system or circuit conductors are installed in parallel in separate raceways or cables, Rule 10-602 requires a bonding conductor to be installed with each set of parallel conductors. When the size of each field-installed bonding conductor is based on Subrule 3) a), Column 1 of Table 16 is applied by dividing the rating of the overcurrent device protecting the conductors by the number of conductors in parallel. When Subrule 3) b) is used, the ampacity of each set of conductors in parallel in the group is applied using Column 2 of Table 16.
Rule 10-616 6)
A metal raceway approved as a bonding means and sized to contain the circuit conductors adequately serves as a bonding means for a given application.
Rule 10-616 7)
A bonding means that is integral to a cable assembly is sized based on the applicable product Standard and is of adequate size for the purposes of this Subrule. See Rule 10-610 2) and 3).
Source: Apppendix B Rule 10-616, CSA C22.1:21, Canadian Electrical Code, Part 1 (25th Edition), Safety Standard for Electrical Installations. © 2021 Canadian Standards Association. Please visit store.csagroup.org