OK Back to your question
Based on my understanding of the Nuckolls Tome, if you're going to run two lights at ~7 AMPS each off the same switch (as I did), and you are feeding the switch with one fuse/breaker (as I did) you need to run a 15 amp breaker (minimum - some would say 14 *1.25 or 17.5 amps) and all the wire in the circuit should be capable of being protected by that 15 (17.5) amp breaker. If not, you could have a short in one wing and the wire would melt before the breaker popped. The fuse/breaker is there to protect the wire. Therefore, you need 14awg for a max 18 ft each leg run with 35C rise. If you want to limit the wires temp increase to 10C, you would need 10 AWG wire (47 ft max). In my case, I ran 12 AWG protected by a 15 amp fuse.
YMMV