Conductors for Class 1 Circuits - Article 725.49(B)

[sirdle]

Article 725.49(B), 2008, says that for Class 1 circuit conductors, "Insulation on conductors shall be suitable for 600 volts. Conductors larger than 16 AWG shall comply with Article 310. Conductors in sizes 18 AWG and 16 AWG shall be type..."

Are those literally the only insulation types that are permitted? Or is Article 725 understood to be a supplement or modification to Article 310... so that the conductor types found in Article 310 could also be used?

 

[don_resqcapt19]

For larger than 16 all of the types in 310 are permitted. For 16 and 18, only the types listed in the code section are permitted.

 

[hbiss]

Class 1 really gets treated as power and you use any Chapter 3 wiring method. Depending on what you are doing it can be better to upsize to 14ga since choices are limited in 18 and 16ga. Basically you have TFFN which like THHN must be run in conduit or raceway. You have type TC (tray cable) which you can use according to it's listing. There is also type MC with 18 and 16ga conductors.

-Hal