NMD90 Non-Metallic Sheath Wiring: This is the most common wiring seen in homes. It consists of an outer jacket which protects the internal conductors during and after installation. The cable is designed to be installed in wood frame buildings and is predominantly made by Loomex and Romex hence the trade name. The cable carries an FT1 fire rating
AC90 (Bx) Armoured Cable Wiring: BX is used primarily in commercial buildings. BX provides good mechanical protection and can be run exposed in all dry locations. BX cable is commonly installed within metal stud framed buildings and where ever mechanical protection is required. Aside from NMD90, BX is probably the next most commonly used cable in the electrical industry. AC90 has an FT6 fire rating and is permitted to be installed within spaces being used as a return air plenum.