334.10(3) allows romex in commercial buildings that are permited to be of type III, IV, and V construction. Romex is allowed in commercial buildings, as long as they are type 3,4,& 5 construction. You can even install romex in type 1 & 2 construction if it”s installed in conduit.Click to see full answer. People also ask, does commercial wiring have to be in conduit?Conduit is typically required where wiring is exposed or where it might be subject to damage. A conduit can be made of metal or plastic and may be rigid or flexible. There are seven different types of conduit used commonly in residential and light commercial wiring.One may also ask, where is Romex not allowed? You can still normally use romex in the walls of non-dwelling occupancies and drywalled ceilings of non-dwelling occupancies. Technically speaking, this section also prohibits you from having any exposed romex in detached garages on a residential property, because detached garages are not a dwelling. Similarly, you may ask, where can NM cable be used? Type NM cable is permitted to be installed in occupancies that are of Types III, IV, and V construction other than dwelling type. However, it must be concealed within walls, floors or ceilings that provide a thermal barrier, per NEC 334.10(3).Can I use Romex in an apartment building?You can use Nm in a six story apt bldg for example as long as you use the Nm within the Dwelling unit . Romex? Type NM cables are approved for multi-family dwellings up to 5 stories of construction types III, IV and V.