SEO Electrical Systems & Wiring 3

Question 1

What is the minimum depth of burial required for UF (underground feeder) cable used for residential outdoor wiring per NEC?

Accepted Answer

18 inches

Answer

NEC Table 300.5 requires UF cable to be buried a minimum of 24 inches, though 12 inches is allowed under certain conduit conditions.

Question 2

In a 240V residential circuit for a dryer, what color combination of hot wires is used?

Accepted Answer

Black and red

Answer

240V circuits use two ungrounded (hot) conductors, typically black and red, each carrying 120V to neutral for a combined 240V.

Question 3

What is the primary purpose of bonding in an electrical system?

Accepted Answer

Ensure all metal parts are at the same electrical potential to prevent shock

Answer

Bonding connects all metal components to maintain equal potential, so no dangerous voltage difference exists between touchable metal surfaces.

Question 4

Which NEC article primarily governs wiring methods and materials for general use?

Accepted Answer

Article 300

Answer

NEC Article 300 covers general requirements for all wiring methods including installation, protection, and conductor fill.

Question 5

What does a three-way switch circuit allow you to do?

Accepted Answer

Control a light from two different locations

Answer

A three-way switch configuration uses two switches and a traveler wire pair, allowing a light to be controlled from two separate locations.

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