I ran into a heating guy thats telling me that a #24 gauge wire can be ran in the same conduit as #14 wire. Can anyone tell me where in the NEC it talks about unlike voltages. Thermostat wire and 120v wiring suppling the furnace is what I'm refering to. Also, does anyone know where the cheapest place to purchase the NEC software. I would love to be able to use the search feature.

Thanks ahead of time.