KNOB AND TUBE fuse protection

[brother]

Its been a while since I had to work with knob and tube wiring. I was reading over Knob and tube and overcurrent protection. I thought there was a section that only 15 amp fuses can be placed on #12 knob and tube wiring. I'm having trouble finding this where can this be found?

 

[don_resqcapt19]

There is nothing in Article 394 that covers the ampacity of knob and tube conductors so the ampacity rules in Article 310 and the overcurrent protection rules in Article 240 apply. #12 will be permitted to have 20 amp overcurrent protection. Prior to the rule in 240.4(D) and its predecessors, knob and tube was often protected based in the 'free air" ampacity tables.