Licensed Electrical Contractor Licensed Electrical Contractor Wiring Methods and Materials Questions and Answers 2

Question 1

What is the maximum number of conductors permitted in a single raceway before derating factors must be applied according to NEC Table 310.15(C)(1)?

Accepted Answer

3 current-carrying conductors

Answer

NEC Table 310.15(C)(1) requires ampacity adjustment when more than 3 current-carrying conductors are installed in a single raceway.

Question 2

Which wiring method is specifically required for circuits supplying fire pumps per NEC Article 695?

Accepted Answer

Type MC cable listed for the application

Answer

NEC 695.6(B) requires wiring to fire pumps to be installed using methods that provide protection against physical damage, with listed Type MC cable being a specifically permitted method.

Question 3

What is the minimum burial depth for rigid metal conduit (RMC) installed under a one-family dwelling driveway?

Accepted Answer

18 inches

Answer

Per NEC Table 300.5, rigid metal conduit under a one-family dwelling driveway requires a minimum cover of 18 inches.

Question 4

When installing EMT in a wet location, what type of fittings must be used?

Accepted Answer

Compression fittings listed for wet locations

Answer

NEC 358.42 requires fittings used in wet locations with EMT to be compression type listed as rainproof or suitable for wet locations.

Question 5

What is the maximum percentage of conduit fill permitted for three or more conductors installed in a raceway per NEC Chapter 9, Table 1?

Accepted Answer

40%

Answer

NEC Chapter 9, Table 1 limits conduit fill to 40% of the raceway's cross-sectional area when three or more conductors are installed.

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Licensed Electrical Contractor Licensed Electrical Contractor Wiring Methods and Materials Questions and Answers 2