define class 2 wiring cable for speakers
The 24 volts used for a thermostat circuit is usually Class 2 wiring. The NEC does not require that thermostat wire or bell wire be installed in raceways, boxes, and auxiliary gutters etc. when these conductors are for Class 2 circuits as defined in Article 725.ection 300.21. The accessible portion of abandoned Class 2, Class 3, and PLTC cables shall be removed. Abandoned Class 2, Class 3, and PLTC cable is defined as that cable that is not terminated at equipment and not identified for future use with a tag.