16 Questions
What listing is required for cables and insulated conductors installed in enclosures or raceways in underground installations?
For use in wet locations
What is the minimum cover requirement for direct-buried cable or conduit in underground installations?
As specified in Table 3.0.1.5
How should underground cable be installed under a building?
In a raceway extended beyond the outside walls of the building
How should direct-buried conductors emerging from grade be protected?
By enclosures or raceways extending to at least 2,400 mm above finished grade
How should conductors entering a building be protected?
To the point of entrance
What is the requirement for direct-buried conductors and cables to be protected from damage?
Protection required from the minimum cover distance below grade to at least 2,400 mm above finished grade
What is the required depth for burying underground service conductors that are not encased in concrete?
450 mm
When subject to physical damage, what type of conduit should be used for installing conductors?
Rigid metal conduit
What kind of backfill should not be placed in an excavation to prevent damage to raceways and cables?
Corrosive material
When are splices or taps allowed for direct-buried conductors or cables without the use of splice boxes?
As long as they are made in accordance with the specified guidelines
What should be provided to prevent physical damage to raceways or cables when backfill contains materials that may damage them?
Suitable running boards
In what scenarios should conduits or raceways through which moisture may contact live parts be sealed or plugged?
When there is a risk of hazardous gases or vapors
What type of conduit is suitable for installing conductors when the enclosure or raceway is subject to physical damage?
Rigid nonmetallic conduit
What should be used to identify the location of underground service conductors buried 450 mm or more below grade?
"Danger: Buried Lines" tape
What materials should not be present in backfill to prevent damage to raceways, cables, or other substructures?
Large rocks and paving materials
What should be used to prevent physical damage to raceways or cable when necessary due to backfill contents?
Granular material
Study Notes
Underground Installations
- Cables and insulated conductors in enclosures or raceways require a listing for underground installations.
- Direct-buried cables or conduits in underground installations require a minimum cover of 450 mm.
Installing Underground Cables
- Underground cables should be installed under a building through a raceway or conduit that is suitable for the location.
- Direct-buried conductors emerging from grade should be protected from physical damage.
Protecting Conductors and Cables
- Conductors entering a building should be protected from physical damage.
- Direct-buried conductors and cables should be protected from damage by using a conduit or raceway that is suitable for the location.
Installing Conductors and Raceways
- Underground service conductors that are not encased in concrete should be buried at a depth of at least 450 mm.
- When subject to physical damage, rigid metal conduit, intermediate metal conduit, or Schedule 40 PVC conduit should be used for installing conductors.
- Backfill containing rocks, stones, or debris that may damage raceways and cables should not be placed in an excavation.
Splices and Taps
- Splices or taps for direct-buried conductors or cables are allowed without the use of splice boxes when made in accordance with the manufacturer's instructions.
Preventing Damage
- When necessary due to backfill contents, physical damage to raceways or cables should be prevented using a conduit or raceway that is suitable for the location.
- Conduits or raceways through which moisture may contact live parts should be sealed or plugged.
Marking Underground Conductors
- Underground service conductors buried 450 mm or more below grade should be identified using a warning ribbon or a marker tape.
Backfill Materials
- Backfill materials that may damage raceways, cables, or other substructures, such as rocks, stones, or debris, should not be used.
- Physical damage to raceways or cables should be prevented using a conduit or raceway that is suitable for the location.
This quiz covers the installation requirements for underground cables, including minimum cover requirements, listing specifications for cables and insulated conductors, and regulations for underground cables installed under buildings.
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