Applied Electrical Flashcards

What is the purpose of a ground fault circuit interrupter (GFCI)?

Answer: To detect ground faults and shut off power quickly

A GFCI monitors the current flowing through hot and neutral wires and trips the circuit when it detects an imbalance, indicating current is leaking to ground, which could cause electrocution.

In a series circuit with three resistors of 10 ohms, 20 ohms, and 30 ohms, what is the total resistance?

Answer: 60 ohms

In a series circuit, total resistance is the sum of all individual resistances: 10 + 20 + 30 = 60 ohms.

What does the color code brown-black-red-gold represent on a four-band resistor?

Answer: 1,000 ohms plus or minus 5%

Brown=1, Black=0, Red=x100 multiplier, Gold=plus or minus 5% tolerance. So 10 x 100 = 1,000 ohms (1k ohm) plus or minus 5%.

Which type of electrical motor is most commonly used in residential HVAC systems?

Answer: Single-phase induction motor

Single-phase induction motors are the standard in residential HVAC because homes typically have single-phase power supply and these motors are reliable and cost-effective for fan and compressor applications.

What is the maximum number of conductors allowed in a standard single-gang electrical box per NEC guidelines?

Answer: It depends on the box volume and conductor size

The NEC requires box fill calculations based on the cubic inch capacity of the box and the size of conductors being installed, with each conductor size requiring a specific volume allowance.

What instrument is used to measure the insulation resistance of electrical wiring?

Answer: Megohmmeter (Megger)

A megohmmeter, commonly called a Megger, applies a high DC voltage to test insulation resistance, measuring values in megohms to verify wiring insulation integrity.