Underground Haz to NonHaz

[Brandon Loyd]

In Class I, Div I and II, is it required to install sealoffs as your conduit comes out of the ground on both ends(enters on one end and exit at the other) from a hazardous to non-hazardous zone? Is PVC coated GRC required for the first 5 feet in hazardous areas where the conduit enters or exits the ground?

 

[rbalex]

In Class I, Div I and II, is it required to install sealoffs as your conduit comes out of the ground on both ends(enters on one end and exit at the other) from a hazardous to non-hazardous zone? ...

As a general statement, a seal is not required at both ends of an underground run where only one end terminates in a classified location; however, it depends on how the various boundaries are defined or, in some cases, the specific application.

Usually, "grade" is considered to be the boundary with below grade treated as ?unclassified.? However, there may be conditions where a boundary may be considered to be below grade or below grade is given a specific electrical area classification. For example, in the 2002 NEC and earlier, Section 514.8 said "Any portion of electrical wiring or equipment that is below the surface of a Class I, Division 1, or a Class I, Division 2 location [as classified in Table 514.3(B)(1) and Table 514.3(B)(2)] shall be considered to be in a Class I, Division 1, location that shall extend at least to the point of emergence above grade." [RBA Note: underline mine]The text was revised in 2005 and makes no distinct statement of below grade area classification but still requires seals at both points of emergence from grade. In any case, the boundaries should be determined by someone qualified to do so. Once the boundaries are properly identified seal locations can be determined.

... Is PVC coated GRC required for the first 5 feet in hazardous areas where the conduit enters or exits the ground?

It is not a general requirement; it will depend on the need for corrosion protection, if any, not on the electrical area classification.