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.”

If the NEC^® requires the electrical wiring methods installed into a hollow space such as a wall to be made so that the wiring methods will not substantially increase (compromise) the fire-resistance rating of the fire wall, then it is critical for the electrician to know which building elements require a fire resistance rating. Unfortunately that information is typically found in the Building Code rather than the Electrical Code.

IBC Section 602.3 specifies that Type III construction is a type of construction in which the exterior walls are of noncombustible materials and the interior building elements are of any material permitted by this code. Fire-retardant-treated wood framing and sheathing complying with Section 2303.2 shall be permitted within exterior wall assemblies of a 2-hour rating or less.