Licensed Electrical Contractor Electrical System Design & Installation 2

Question 1

When sizing conductors for a continuous load, the conductor ampacity must be at least what percentage of the load's ampere rating per NEC 210.19?

Accepted Answer

125%

Answer

NEC 210.19(A)(1) requires conductors for continuous loads to be sized at 125% of the continuous load ampere rating.

Question 2

Which conductor material requires anti-oxidant compound when terminating at devices or equipment?

Accepted Answer

Aluminum

Answer

Aluminum conductors oxidize at connections, so anti-oxidant compound is required to ensure a reliable, low-resistance termination.

Question 3

A 240V single-phase motor draws 28 amperes at full load. The minimum branch circuit conductor size using 75°C copper wire (THWN) is:

Accepted Answer

8 AWG

Answer

Motor branch circuits must be sized at 125% of FLA: 28A × 1.25 = 35A, requiring 8 AWG THWN copper rated at 50A.

Question 4

Which NEC article governs the installation of electrical systems in hazardous (classified) locations?

Accepted Answer

Article 500

Answer

NEC Article 500 covers hazardous (classified) locations, defining Class I, II, and III divisions and zones.

Question 5

In a delta-wye transformer installation, which winding configuration provides a neutral conductor on the secondary side?

Accepted Answer

Delta primary, wye secondary

Answer

A delta-wye configuration provides a neutral on the wye secondary, enabling 3-phase 4-wire distribution systems.

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