C7 C7 Audio Visual & Communication Systems 5

Question 1

A C7 low-voltage contractor must pull a communication cable through the same conduit as a 120V branch circuit. Which NEC section generally prohibits this practice?

Accepted Answer

NEC Article 800.133

Answer

NEC Article 800.133 prohibits communications cables from being installed in the same raceway or conduit as electrical light and power conductors.

Question 2

What is the primary purpose of a DSP (Digital Signal Processor) in a commercial AV system?

Accepted Answer

To route, mix, equalize, and apply dynamics processing to audio signals

Answer

A DSP performs routing, mixing, EQ, compression, delay, and other real-time processing on audio signals within a single digital domain.

Question 3

In a structured cabling installation, the maximum total channel length for a permanent link plus patch cords in a Class D (Cat5e) channel is:

Accepted Answer

100 meters

Answer

TIA-568 specifies a maximum channel length of 100 meters (328 ft) for Class D/Cat5e, including up to 10 meters of patch cords.

Question 4

A retail store needs background music distributed to 20 ceiling speakers. To maintain consistent volume levels at different distances from the amplifier, the installer should use:

Accepted Answer

A 70-volt distributed audio system with tap transformers

Answer

A 70-volt system with tap transformers allows each speaker to be set to a specific wattage tap, maintaining consistent volume regardless of distance or total speaker count.

Question 5

Under the California C7 license, which of the following work requires a separate C-10 Electrical Contractor license and CANNOT be performed by a C7 licensee alone?

Accepted Answer

Installing a 120V dedicated outlet for an AV rack

Answer

Line-voltage electrical work such as installing 120V outlets requires a C-10 Electrical Contractor license; C7 licensees are restricted to low-voltage systems.

(C7) California C7 Low Voltage Systems Contractor Certification Practice Test

(C7) California C7 Low Voltage Systems Contractor Certification Practice Test

C7 C7 Audio Visual & Communication Systems 5