Answer:
4 conditions
Step-by-step explanation:
The National Electrical Code (NEC) provides safety guidelines for the installation of electrical wiring and electrical equipment in the United States. The purpose behind NEC is to standardize the safe electrical installation practices.
There is always a confusion among people to distinguish between inside or outside of a building or structure. Therefore, NEC has listed 4 conditions in the Article 230.6 where it has mentioned conductors to be considered outside a building or structure.
Conductors are considered outside a building when they are installed:
1. Under not less than 2 inches of concrete beneath a building or structure.
2. Within a building or structure in a raceway that is encased in no less than 2 inches thick of concrete or brick.
3. Installed in a vault that meets the construction requirements of Article 450, Part III.
4. In conduit under not less than 18 inches of earth beneath a building or structure.