Commercial Wiring

The correction factor for a conductor with 75 degree C insulation that is installed in a 104 degrees F ambient temperature is ________________.

0.88

Ampacities of NEC Table 310.16 is based on not more than ___________ current-carrying conductors in a raceway, cable, or earth based on an ambient temperature of __________ degrees F.

1. Not more than three current carrying-conductors in a raceway, cable, or earth based on ambient temperature of 2. 30 degrees C (86 degrees F) pg. 52

The definition of ampacity is "The____________ current, in amperes, that a conductor can carry ____________ under the _____________ of use without exceeding its ___________ rating".

1. The max current, in amperes, that a conductor can carry 2. Continuously under the 3. Conditions of use without exceeding its 4. Temperature rating Pg. 51

The ampacity of 400 kcmil copper conductors for: 60 degrees C insulation: 75 degrees C insulation: 90 degrees C insulation:

60 degrees C insulation: 280 75 degrees C insulation: 335 90 degrees C insulation: 380

If conduits or cables are installed within 7/8 in. of a rooftop with sunlight exposure, the following temperature must be added to ambient temperature for the application of the correction factor: _________________ F

60 degrees F

For the same size of the conductor, aluminum conductors have a (higher) (lower) ampacity then do copper conductors.

Aluminum conductors have lower ampacity than copper conductors. Pg. 54

Conductors with a -2 insulation designation have a (higher) (lower) ampacity in a wet location than do conductors without the designation.

Have a higher ampacity in wet locations than conductors without the designation. pg. 52

Which of the following two insulation types are more likely to soften when heated? 1. THWN 2. XHHW

THWN Reason: thermoplastic insulation if heated above its rated temperature can soften and melt. Pg. 54

If nine current-carrying conductors are installed in one raceway for a length greater than 24 in., the ampacity must be reduced to ___________ percent.

The ampacity must be reduced to 70% or 60% pg. 60 and NEC Table 310.15(C)(1)

Describe what the following conductor designation means when it is printed on the insulation; RHH/RHW/USE

Triple-rated USE = direct burial RHH = in or on buildings or structures in dry locations at 90 degree ampacities. RHW = in or on buildings or structures in wet locations at 75 degrees ampacities

The proper size and type of conductor must be installed to comply with manufacturers installation instructions (True) (False)

True NEC 110.3(B) Pg. 51

Indicate whether the following conductor installations that are installed in conduits or cables within 7/8 in. of a rooftop having sunlight exposure are required to have the correction factor applied: a. THW b. THWN c. THWN-2 d. USE-2 e. XHHW f. XHHW-2

a. THW b. THWN c. THWN-2 (yes) d. USE-2 e. XHHW f. XHHW-2 (no)