Greg the load is not the issue with the NECs present rules on derating.
Let me ask this.
If this was only one 1.3 amp fixture on a dedicated circuit could I run 14 AWG to it but still use a 20 amp OCP?
No, because the rules of 240 require a conductor for this application to be rated higher then the OCP.
Now when we derate the ampacity of the conductor we must not use an OCP above that adjusted rating.
Thirteen 12 AWGs in a raceway have a rating of 15 amps at best, so we would need to drop the OCP down to 15 or increase the wire size to 10 AWG.
Bob
[This message has been edited by iwire (edited 09-08-2005).]
