Question 1

The ____ system has the advantage of needing only two transformers to provide three-phase voltage.&#10;A) high-leg&#10;B) delta&#10;C) single-phase&#10;D) open-delta

Accepted Answer

The open-delta system, also known as the V-V connection, only requires two transformers instead of three typically found in a delta or wye connection. However, it has some disadvantages, such as lower power capacity and the inability to withstand a failure of one transformer.

Question 2

The overload protection for a dual-element time delay fuse is provided by a ____.&#10;A) solder link&#10;B) spring&#10;C) lever&#10;D) standard lock

Accepted Answer

The overload protection in a dual-element time delay fuse is provided by a solder link, which melts under overload conditions, opening the circuit and protecting the wiring.

Question 3

Wye-connected systems often use a fourth conductor connected to the back of the connection.

Accepted Answer

Wye-connected systems often use a fourth conductor known as the neutral wire, which is connected to the common point of the connection, not the back.

Question 4

The three-pole breaker cannot be used in a single-phase panel.

Accepted Answer

Three-pole breakers are designed for three-phase systems and cannot be used in a single-phase panel. Single-phase panels require single-pole or double-pole breakers.

Question 5

In the United States and Canada, power is generated as a three-phase 50-hertz voltage.

Accepted Answer

Power in the United States and Canada is actually generated as a three-phase 60-hertz voltage.

Question 6

Fuses for air conditioning and refrigeration equipment are normally sized at ____ of the rated full-load current of the motor.&#10;A) 75%&#10;B) 125%&#10;C) 175%&#10;D) 225%

Accepted Answer

Fuses for air conditioning and refrigeration equipment are typically sized at 175% of the rated full-load current to allow for the initial surge of current when the motor starts.

Question 7

A type of three-phase service is known as the open delta.

Accepted Answer

Open delta is a type of three-phase service in which only two transformers are used instead of the usual three. It is also known as the V-V connection or the "fork" connection.

Question 8

An alternator is a generator that produces AC voltage.

Accepted Answer

An alternator is a type of generator that produces AC voltage.

Question 9

When servicing equipment, a small ____ should be used to lock the disconnect in the off position.&#10;A) padlock&#10;B) lever&#10;C) paper tag&#10;D) label

Accepted Answer

A padlock should be used to lock the disconnect in the off position to prevent accidental or unauthorized re-energization of the equipment. A lever, paper tag, or label may not provide sufficient security to prevent the equipment from being turned back on.

Question 10

When a(n) ____ connection must be made, a two-pole circuit breaker is used.&#10;A) 108-volt&#10;B) 110-volt&#10;C) 120-volt&#10;D) 240-volt

Accepted Answer

When a high-voltage connection needs to be made, a two-pole circuit breaker is used. The voltages listed in options A, B, and C are all considered standard residential voltages and therefore do not require a two-pole circuit breaker. Option D, 240-volt, is a voltage commonly used for larger appliances such as electric dryers or ovens and requires a two-pole circuit breaker for safety reasons.

Deck 5: Electrical Services