Well, it bothered me enough to contact CSA. Here's the email reply:
All circuit breaker have been certified for use with 75 C conductor ampacity ratings. Circuit breakers are marked somewhere on the circuit breaker with a label that says, “60/75C wire”. Since all circuit breakers are marked the Rule doesn’t require the 75 C to be specified. This came about in the 2012 Canadian Electrical Code, when Rule 4-006 was changed. This now means that if a conductor terminates on a circuit breaker you must use the 75C column from Tables 1, 2, 3 or 4 to determine it maximum ampacity rating. We didn’t put the breaker temperature in the questions as the C of Q Exam doesn’t have to and also we didn’t want you to think that circuit breakers come with 90 C ratings.
4-006 Temperature limitations (see Appendix B)
(1) Where equipment is marked with a maximum conductor termination temperature, the maximum
allowable ampacity of the conductor shall be based on the corresponding temperature column from
Table 1, 2, 3, or 4.
(2) Where equipment is not marked with a maximum conductor termination temperature, 90 °C shall be used
by default.
Let me know if I can be of any further assistance.
Regards,
Robert Nelson
Senior electrical Consultant – Learning Services
CSA Group
