A mixed use occupancy can contain several classifications and is likely to have fire rated separation walls, floors, or ceilings to separate the different uses of the building.

A large hotel might have several classifications such as R-1 for the sleeping units, A-2 for the restaurant or indoor swimming pool, Group B for the business offices, Group M mercantile for the gift shop.

In mixed use buildings, pay special attention when penetrating walls, floors or ceilings to install wiring methods in order to maintain the required fire resistive rating of the different occupancy types.

NEC 300.21 requires the following regarding the Spread of Fire or Products of Combustion.

“Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating.”

In addition, “electrical equipment rooms” are required by IBC 1008.3.3 to have emergency lighting even though NEC^® 700.16 would only require emergency lighting in the electrical equipment room if the electrical equipment contained a service disconnect in accordance with NEC^® 230.70, or a disconnect for feeders or branch circuit conductors that supply or passthrough the building or structure per 225.31.