Well I think I now have answers to all three of my original questions (Thanks everybody):1) Can I use conventional (black, white, gnd) BX, red tape on the white wire to ID as hot conductor.
YES2) Regarding the thermostat, the one I have has two poles, I have seen these connected two different ways in the past, method one, they switch two heaters, one on each pole. Method two they switch both poles to either one heater or two in parallel. Not sure what the code book says about this?
Must switch both poles3) I have existing spare conventional 15A dual pole breakers in the panel, can I use these or are arc-fault breakers required?
Conventional breakers are OKNot one of my original questions, but it did come up during the discussion regarding the neutral.......
Quote
622-110 - Branch circuits which supply electric heaters may not be used to supply any other load.
2-wire cables - electric heaters are usually connected for 240V - no connection to the neutral. Rule 4-034(1) permits a 2-wire loomex cable with one black and one white to be used for these loads. ... A little black or red tape on the exposed section of the white conductor.