Which Wire Should Be Used in Conduit?

NEC is the National Electrical Code. It is the governing code for the installation of electrical components and equipment. According to the NEC Code book 2011 edition, there are three basic applications for conduit.

Underground Wires

Any wires that are being buried underground should be in conduit to protect them from any damage. PVC conduit can be used for this application according to section 300.5 of the NEC. According to section 300.50(A)(1), any non-shielded cables shall be put into rigid metal or nonmetal conduit. This even includes service wires.

Water or Wet Environment

According to the NEC table 300.50 (B), interior of conduit or raceways installed underground shall be considered a wet location. These cables need to be for use in wet locations and are to comply with 310.10(C). Any wires involved within a circuit that will be in a wet environment need to be sealed within conduit that will be watertight.

Protection from Damage

Any conductors that come out of the ground are required to be in rigid metal or intermediate metal conduit on poles. Schedule 80 PVC conduit or its equivalent shall extend from the minimum cover depth specified within Table 300.50 of the NEC to a point eight feet above the finished grade. Conductors entering a building are also to be protected within conduit or raceway. Any wires that are in a possible environment that they could be damaged should be in conduit.

References

• NFPA 70 National Electrical Code, 2011 Edition