I always thought the 0" meant that the wiring method could't be used in the particular situation. What is considered " under a building"? we are talking about in a slab not under it. wouldn't that be all other locations?
Re: conduits in concrete floor slabs#88563 06/28/0402:06 PM06/28/0402:06 PM
It is my understanding that Article 300.5 "Underground Installations" and Table 300.5 was specifically for conduits installed underground or under slabs. No where does the code state for conduits installed "within" floor/ceiling slabs. If you are refering to table 300.5, "All locations not specified below" then for RGS would need to have 6" cover in a slab. This cant be right.
James Wright Project Enginner I
Re: conduits in concrete floor slabs#88564 06/28/0407:15 PM06/28/0407:15 PM
The building code (2003 IBC) has this to say: "1906.3 Conduits and pipes embedded in concrete. Conduits, pipes and sleeves of any material not harmful to concrete and within the limitations of ACI 318, Section 6.3, are permitted to be embedded in concrete with approval of the registered design professional."
And, generally the cover requirements are the same as for rebar:
TABLE 1907.7.1 MINIMUM CONCRETE COVER
CONCRETE EXPOSURE MINIMUM COVER 1.Concrete cast against and permanently exposed to earth 3"
2.Concrete exposed to earth or weather No. 6 through No. 18 bar 2" No. 5 bar, W31 or D31 wire, and smaller 1½"
3.Concrete not exposed to weather or in contact with ground Slabs, walls, joists: No. 14 and No. 18 bars 1½" No. 11 bar and smaller ¾" Beams, columns: Primary reinforcement, ties, stirrups, spirals Shells, folded plate members: 1½" No. 6 bar and larger ¾" No. 5 bar, W31 or D31 wire, and smaller ½"
Engineers and concrete contractors look at embedded conduit as a necessary evil. Conduit doesn't provide much in the way of strength and can often weaken the concrete if not installed correctly. Keep your embedded conduit runs at least 2 inches back (or structural engineer's requirements) from the finish to avoid "pop-outs", and allow space between the conduit and the rebar for the aggragate to flow all around both. If installing in floor slabs, install the conduit under the wire mesh.