Where knob-and-tube conductors pass through wood cross members in plastered partitions, conductors shall be protected by noncombustible, nonabsorbent, insulating tubes extending not less than _____ beyond the wood member.
a) 2 in.
b) 3 in.
c) 4 in.
d) 6 in.
See answer and applicable Code reference
The correct answer is: b) 3 in.
Article 394 covers the use, installation, and construction specifications for concealed knob-and-tube wirin