Yes I forgot the derating of more than 3 current carrying conductors. I think this is a old issue. So far I am getting away with 40A breaker with Nema 14-50 or Nema 6-50 receptacle in the greater Vancouver area (residential/commercial).
You shouldn't be. Here's the OESC rule, I know the CEC has it, I just don't feel like looking for it:
OESC 2021 Rule 26-700 2) - Receptacles having configurations in accordance with
Diagrams 1 and 2 shall be connected only to circuits having a nominal system voltage
and ampere rating corresponding to the rating of the configurations.
Only exception is for a range receptacle in a kitchen may be permitted to be installed on a 40A OCPD.
What's the termination temp of your circuit breakers and the receptacles? They have to go on a 50 amp OCPD to be code compliant.
The argument about #8 on a 50 has been discussed and continues to be discussed. I won't comment on it.... I'd run #6 and be done with it.
