mtnelect
HVAC & Electrical Contractor
- Location
- Southern California
- Occupation
- Contractor, C10 & C20 - Semi Retired
Conductor ampacity
- Thread starter Jpflex
- Start date
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Therealcrt
Senior Member
- Location
- Kansas City
- Occupation
- Electrician
Is this thread still going on? Down the rabbit hole I can see lol. If anyone is wondering, YouTube Dave Gordon he is the best at explaining way better than Mike holt.
Basically you size the conductor in table 310.16 based on the lowest temperature rating of anything connected in that circuit. You can use the 90c column to make all of your corrections and use that size conductor as long as it’s not higher than the specified column that you must use. Which is either 60 or 75. If the circuit doesn’t pertain to 240.4 E or G only then small conductors 10.12.14 must be on their respected OCPD no exceptions 30,20,15.
Even if there’s more than 3 CCC you can still use the 310.16 table you just have to derate the conductors which means choosing a larger conductor most likely based on the # of CCC in a raceway if using a raceway..
Now here’s the trick they throw at you . 100a or less it says you must use the 60c column.. but if all the connected equipment or devices are all rated higher (75c) then you can use the 75c column.
So next time your Forman says put that #12 on a 30a breaker it’s rated for it. Make sure it pertains to either provision in 240.4 E or G . Otherwise he or she is wrong!
Stay classy, Local124
Basically you size the conductor in table 310.16 based on the lowest temperature rating of anything connected in that circuit. You can use the 90c column to make all of your corrections and use that size conductor as long as it’s not higher than the specified column that you must use. Which is either 60 or 75. If the circuit doesn’t pertain to 240.4 E or G only then small conductors 10.12.14 must be on their respected OCPD no exceptions 30,20,15.
Even if there’s more than 3 CCC you can still use the 310.16 table you just have to derate the conductors which means choosing a larger conductor most likely based on the # of CCC in a raceway if using a raceway..
Now here’s the trick they throw at you . 100a or less it says you must use the 60c column.. but if all the connected equipment or devices are all rated higher (75c) then you can use the 75c column.
So next time your Forman says put that #12 on a 30a breaker it’s rated for it. Make sure it pertains to either provision in 240.4 E or G . Otherwise he or she is wrong!
Stay classy, Local124