Wiremold/Legrand has introduced fire-classified metal and nonmetallic floor boxes that preserve the fire rating of a concrete slab without spraying on additional insulating material. These first-in-the-industry boxes are fire-classified assemblies that are UL® tested and shown not to impact a floor's fire rating. They eliminate uncertainty concerning the location and amount of sprayed-on insulation to be applied, and also increase installation efficiency.

Unlike conventional floor boxes, Wiremold® fire-classified floor boxes have conduit stubs that extend downward, penetrating the steel decking into the space below. The stems of steel floor boxes contain intumescent firestop material that, when exposed to high temperatures, expands and effectively seals the penetration from flames and heat. In addition, a pad made of insulating material is secured under the metal floor box to control heat propagation through the box into the space above. Because nonmetallic floor boxes do not conduct heat, intumescent material located within the box itself is sufficient to maintain the fire rating.

Wiremold/Legrand offers 12 fire-classified floor boxes, including the Omnibox Multiservice Series, RFB Series Recessed Floor Boxes, and round and rectangular nonmetallic floor boxes.