D2 - LT4 - CEC Section 12 Wiring Methods

Question 1

What is the general rule for all underground installation depths?

Rule 12-012

Answer 1

minimum depths of cover are required

cover refers to the minimum distance between the top surface of the installation and the finished grade

Refer to Subrule(1) Table 53 to find minimum depths of cover

Question 2

What additional precautions are taken for underground installations?

Rule 12-012

Answer 2

Subrules (4) & (10)

require a bed of screened sand around the installation with clean backfill over top.

This ensures that large objects will not corrode or penetrate through the sand bed, damaging the installation

Question 3

What happens if the minimum cover requirements cannot be reached?

Rule 12-012

Answer 3

Subrule (2)

permits a reduction of 150mm, provided a suitable form of mechanical protection is placed above the installation.

Subrule (3) lists the approved forms of protection

Question 4

What does NMSC stand for?

Answer 4

Non-Metallic Sheathed Cable

Question 5

What considerations are taken when selecting the correct conductor?

Answer 5

• moisture
• corrosive action
• temperature
• degree of enclosure
• mechanical protection

Question 6

What is NMSC?

Answer 6

an assembly of 2 or more insulated conductors having an outer sheath of non-metallic, moisture-resistant, flame-retardant, insulating material.

is available with 2, 3 or 4 current-carrying conductors ranging in size from #14 AWG through to #2 AWG

Has a voltage rating of 300V

2-wire NMSC contains a black, white, and bare (or green) conductor

3-wire NMSC contains a black, white, red, and bare (or green) conductor