NCED Electrical Systems & Wiring 3

Question 1

Ohm's Law states that voltage equals current multiplied by which quantity?

Accepted Answer

Resistance

Answer

Ohm's Law: V = I × R, meaning voltage (V) equals current (I) in amperes multiplied by resistance (R) in ohms.

Question 2

What is the function of a circuit breaker compared to a fuse?

Accepted Answer

A breaker can be reset after tripping; a fuse must be replaced

Answer

The key difference is that a circuit breaker is a resettable mechanical switch, while a fuse must be replaced once its element melts.

Question 3

What voltage is standard for most 240V appliance circuits (dryers, ranges) in US homes?

Accepted Answer

240 V (two 120V hots + neutral)

Answer

US 240V circuits use two hot legs each at 120V with respect to neutral, providing 240V between the two hots for large appliances.

Question 4

Which NEC rule governs the maximum number of conductors allowed in a junction box?

Accepted Answer

Box fill calculation based on cubic inch capacity

Answer

NEC requires a box fill calculation: each conductor, device, and fitting occupies a certain cubic-inch volume, and the total must not exceed the box's rated capacity.

Question 5

What does the term 'service entrance' refer to in residential electrical work?

Accepted Answer

The point where utility power enters the building and connects to the main panel

Answer

The service entrance is the set of conductors and equipment (meter socket, service head, main panel) that bring utility power into a building.

(NCED) Nationally Certified Educational Diagnostician Practice Test

(NCED) Nationally Certified Educational Diagnostician Practice Test

NCED Electrical Systems & Wiring 3