Q. Can I use SER cable in a 4-story multifamily dwelling?
A. NM and SE cables can only be used in multifamily dwellings permitted to be of Types III, IV, and V construction [334.10(A) and 338.10(B)(4)(a)]. The number of stories does not enter into the requirements. Types of construction are covered in the applicable building codes (such as the International Building Code), and are not covered in the NEC. In a nutshell, the type of construction means the types of material a building can be constructed of, such as wood, concrete and steel. Because this is a difficult topic for electricians to deal with, your best bet is to consult with the building official of the city/county you're working in.