309A Wiring Methods and Materials 2

Question 1

What is the primary advantage of using MC (metal-clad) cable over NMD90 in commercial applications?

Accepted Answer

Mechanical protection from the metal armour

Answer

MC cable's interlocking metal armour provides superior mechanical protection compared to NMD90's non-metallic sheath, making it suitable for exposed commercial and industrial installations.

Question 2

What is the CEC requirement for supporting NMD90 cable within a distance of an electrical box?

Accepted Answer

Within 300 mm

Answer

CEC Rule 12-510 requires NMD90 cable to be supported within 300 mm of every box, cabinet, or fitting to prevent strain on the connections.

Question 3

What type of raceway is most suitable for a corrosive chemical processing environment?

Accepted Answer

PVC conduit (Schedule 40)

Answer

PVC conduit is highly resistant to chemical corrosion and is the preferred raceway material in corrosive environments such as chemical processing plants.

Question 4

What is the maximum percentage fill for a wireway (auxiliary gutter) according to the CEC?

Accepted Answer

75%

Answer

CEC rules permit wireways to be filled to a maximum of 75% of their cross-sectional area at any point, providing more space than conduit but still allowing for adequate wiring access.

Question 5

When is it acceptable to use flexible metal conduit (FMC) as the sole equipment grounding conductor?

Accepted Answer

When the conduit is 25 mm trade size or smaller and the circuit is 20 A or less

Answer

The CEC permits FMC to serve as the equipment grounding conductor only when the trade size is 25 mm or smaller and the circuit overcurrent device rating does not exceed 20 A.

Red Seal Electrician 309A Practice Test

Red Seal Electrician 309A Practice Test

309A Wiring Methods and Materials 2