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Discussion Starter · #1 ·
So in the Ontario code 14-104(2) states breaker sizes for #14, #12 and #10. Table 2 is mainly used for derating. So besides common knowledge, what's the max breaker size on a #8 or #6? (No motors or other rules bypassing the general rules of course).
 

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It depends on temp rating of equipment and temp of wire.
#8awg copper 40 amps
#6awg copper 55 amps
Most breakers are 60 degree that I have seen watch for the temp rating on the end device as well disco,receptacle, etc
 

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So in the Ontario code 14-104(2) states breaker sizes for #14, #12 and #10. Table 2 is mainly used for derating. So besides common knowledge, what's the max breaker size on a #8 or #6? (No motors or other rules bypassing the general rules of course).
I know you are asking about the CEC but I think it is odd asking what the largest breaker size for wire without applying the entire code. :blink:
 

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Who knows what the actual max is.. but it's going to be a lot big number than 40amps for #8 and 55amps for #6.

Start looking into breaker sizing for capacitors, motors and transformers. One of those will probably be it.
 

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Got this from ESA bulletin #4-12-1 (Sorry, images didn't work)

The ampacity of the conductors connected to a breaker as per Photo B1 or a switch as per Photo B2 that are marked with maximum temperature rating of field-installed conductors ( 75°C) need to be determined based on the marked temperature (75°C column from Tables 1, 2, 3 and 4). When a breaker or a switch has dual marking (such as 60/75°C), the ampacity of field-installed conductors is permitted to be determined based on the higher temperature (in this case 75°C column of appropriate tables).

8awg = 50 amp breaker. 6awg = 60 amp breaker (Under normal conditions)
 

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Discussion Starter · #6 ·
BlackHowling said:
It depends on temp rating of equipment and temp of wire. #8awg copper 40 amps #6awg copper 55 amps Most breakers are 60 degree that I have seen watch for the temp rating on the end device as well disco,receptacle, etc
You're going by the 60C column in table 2. If we did it that way then a #14 could go on a 20A breaker and a #12 on a "25A".

Since 14-104(2) doesn't allow this for 14, 12 and 10 AWG , why would we start doing it for the rest if the sizes?
 

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Discussion Starter · #7 ·
BBQ said:
I know you are asking about the CEC but I think it is odd asking what the largest breaker size for wire without applying the entire code. :blink:
I don't think it's odd to talk about general ccts. Whenever questions come up about general rules electricians start talking about motors etc (more fine tuned codes) that aren't related to the actual question at hand.
 

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Aegis said:
You're going by the 60C column in table 2. If we did it that way then a #14 could go on a 20A breaker and a #12 on a "25A". Since 14-104(2) doesn't allow this for 14, 12 and 10 AWG , why would we start doing it for the rest if the sizes?
Find me a breaker rated higher than 75 degrees

14-104 Rating of overcurrent devices (see Appendix B) (1) The rating or setting of overcurrent devices shall not exceed the allowable ampacity of the conductors thatthey protect, 

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.
 

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It's an odd question only because there's not many general use circuits that would require #8 or #6 wire. Usually when you get up in that size you're feeding something specific, which usually has it's own set of rules governing the OCPD.
 
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