I have recessed lighting in my bathroom. The home was built in the 70's with remodeling done in the late 90's early 00's. When I use a certain electrical appliance in this room, the lights flicker. Additionally, the applicance has burned itself out 3 times in the last year. The company keeps sending me a new one since it is under warranty, but its annoying and I can't help but wonder if its burning out because of the wiring in some way. The appliance is a hair straightener that claims to be ionized. The lights flicker when I squeeze the plates together to straighten my hair. I hope I've explained this enough. I know it sounds strange. Why are the lights flickering and why is the appliance burning out?

As background, I am familiar and comfortable with 12 and 14 gauge wiring for various projects throughout the house. Now, I am remodelling/rewiring an old kitchen in which armored cable feeds the 50A range outlet. When rewiring this range circuit, do I need to use armored cable as before, or can I use NM cable? If NM, is any other protection or sheathing required by most codes? I will be pulling this through wood framing, if that matters. There will be a recessed outlet, with no exposed wiring (except on the approach to the circuit breaker panel). My local superstore has 6-3 NM Romex with what appears to be stranded conductors (as opposed to the solid conductors in the more familiar 12 or 14 gauge Romex I have previously installed. The 6-3 has black exterior NM sheathing and they will cut it for me to order. I have 7/8" auger drill bit on hand, looks like it will be a good fit. Any and all advice appreciated. thanks