CFESA ELECTRICAL PRACTICE TEST

A capacitor start motor should be used in what applications?

used for heavy-duty applications requiring high starting torque. refrigerator compressors, pumps, and conveyors.

You have 120 V super warmer that is not heating. Your meter reads 120 V from each side of the element to the ground. The voltage across the element reads 0 V. What is the issue?

Open neutral after the element

If you check each side of an element terminal to ground and read 120 V does that mean the element has voltage to it?

No measure voltage across the load, not from each terminal to ground

A ground fault breaker is considered more reliable than a ground fault receptacle. T or F?

True

A thermostat has a differential of 5°F. This means:

the temperature needs to drop 5 degrees below the set point before the heating system turns on

Wall receptacles failed due to:

loose wires, overloaded circuits (tripped breakers), damaged internal components, wear and tear from frequent use, exposure to moisture, or physical damage which can lead to poor connections or short circuits.

It is still possible to get shocked by touching the casing of a piece of equipment if it is properly grounded. T or F?

False

Before working on electrical equipment with the power on:

Proper PPE must be worn, example of this is linesman's gloves

Add 240 V range connected to a 208 V power supply will:

it will likely operate with reduced power and potentially experience issues like longer cooking times, decreased heating efficiency, and could potentially be damaged over time

AC power has a negative and a positive line. T or F?

False, it has a hot and a neutral

Which formula should you use to determine the power consumed by a 15 ohm heater element with 8 A of current flowing through it?

P= I x I x R

A hot line in an AC power supply contains 120 V. T or F?

False, 120 volts is the difference in potential between the hot line and neutral.

On the ohms law wheel what does P stand for?

Power

Line voltage is the potential difference between:

any two lines and phases in a three-phase electrical system; essentially, the voltage measured between two live wires in a power circuit.

Prefix Milli means:

1/1000

The total resistance of a unit but the 230 amp heating elements connected in a series is:

The total sum of the individual resistances- RT= R1+R2+R3...

The total resistance in an parallel circuit is called:

1/RT= 1/R1+1/R2...

Power defined by the ohms law formula:

Amount of electrical energy used

Any thermostat that fails in a closed contact position:

Most likely carried an excessive load. The thermostat was used in a power duty application or the thermostat was involved in a short-circuited load.

If a blower keeps coming off the motor shaft after it runs for a while:

This usually indicates a worn hub on the blade

Higher voltage supplies are used to:

Decrease wire size and save costs, they also are needed for modern luxuries such as Central A/C, driers, etc.

A wild leg must always be connected where on the terminal block on a three phase equipment?

A "wild leg" (also called a "high leg") in a three-phase system should always be connected to the designated "B" phase terminal on a terminal block, as per standard electrical practice, which usually marks the phase with the higher voltage to neutral as "B" phase, it must not go on the 120 v terminal.

Voltage between the Hotline and neutral of a 208 V power supply:

120V

On the ohms law wheel what does R stand for?

Resistance(ohms)

When your customer leans over metal counter and touches the toaster a shark is received. You have checked the toaster and the ground circuit is complete. You should:

Unplug and inspect the grounding

A 208 V fryer connected to a 240 V supply could have what results?

35% more power can affect the cooking characteristics of the equipment. This can cause damage to the components.

Jerry is working at a job site where the voltage to the building is 208 V. The oven the customer just got is 240 V. What kind of transformer will he get?

Step up transformer

The neon signal light can be connected across the contacts of a high limit temperature thermostat to indicate when the control opens because:

it will only light up when the thermostat contacts are open, breaking the circuit to the load

. If the element shorts to ground when the switch is closed:

Short circuit occurs

To properly check a regular transformer you should?

always check output with load connected

I warmer has an infinite switch but the terminal literally burned out of it.

If an infinite switch burns up at the terminals, the wiring and the terminal connectors have to be replaced as they have been damaged

What does prefix Micro mean

1/1000000 or 1/1 millionth

What does prefix kilo mean

1000 times

What does prefix mega mean

1000000 times or 1 million times

What does prefix milli mean

1/1000 or 1/1 thousandth

What happens to current in a parallel circuit?

It divides across the resistances

What happens to voltage across the loads in a parallel circuit

Stays the same

What happens to voltage across loads in a series circuit

It divides across the resistances

What happens to the current in a series circuit?

It stays the same everywhere

What is the voltage between two hot lines in a 230 V system?

230 V

What is the voltage between two hot lines in a 208 V system?

208 V

What is the voltage between a hotline and a neutral and a 230 single volt phase supply

115 V

What is the voltage between a hotline and a neutral in a 208 single volt phase supply

120 V

What is the voltage between any two hotlines of a 230 V Delta power supply?

230 V

What is the voltage between a hot line and a ground on a 240 V delta power supply

No usable voltage

What is the voltage between any two hot lines of a 230 V grounded delta power supply

230 V

What is the wild leg?

Leg with higher than 120 V to ground or neutral

What danger is presented by the wild leg?

High voltage that will damage 120 V components in the circuit

How do you determine which hotline is the wild leg in a 250 V grounded delta power supply

The one that does not measure 120 V to a neutral or ground

Approximately how much will the wattage increase on a 208 V piece of equipment if it is connected to 240 V supply

33%

Approximately how much will the rated wattage decrease if 240 V equipment is connected to a 208 V supply

25%

What damage could potentially be caused to the supply wiring F208 V equipment is connected to a 240 V supply

Higher wattage created with damage heaters or other components

How can the cooking characteristics of equipment be changed by low supply voltage?

slow recovery time, uneven cooking

When is the most opportune time to discover a high or low-voltage problem?

At equipment startup before the equipment is energized

Can high-voltage result in overheating problem when trying to control the temperature of an oven?

Yes

What is the formula for calculating the current draw from the wattage and voltage on a three phase balanced load?

amperage = wattage / (voltage X 1.732)

How should the Earth ground from the main fuse or breaker panel be connected?

from grounding bus bar to ground rod or metal water pipe

In order for a receptacle to be properly grounded, the ground wire must run to where

all the way back to the panel

How much resistance should you read from neutral connection to a ground connection

0 ohms

What is the difference between neutral and ground?

The neutral normally carries current, the ground does not

Can you get shocked from the casing on a piece of equipment if it is properly grounded

No

Ground wires must always be what colors

Green, green with yellow tracer, or bare wire

How much current does a short circuit draw?

Infinite amps

If a cord on a piece of equipment is shorted, can it damage the power switch on the piece of equipment

No

If a heating element on an electrical is shorted, could it damage the thermostat?

Yes

If a power switch is shorted on a heat lamp, could it damage the heating element?

No

When checking voltage, you must touch your meter leads where

Across the load you are measuring

If you check each side of an element terminal to ground and you read 120 V, does that mean that the element has voltage to it?

No

What size THHN wire should be used for a 20 amp load

12 gauge

What size TGGT wire should be used for a 30 amp load?

12 gauge

Give three common reasons for wire failures

Undersized, temperature rating too low, poor connections

Why must burn or discolored wire be replaced?

Once burned or discovered the current carrying capacity drops significantly also connections will overheat

If you put new terminals on discolored wire, what will happen?

they will burn off again

Many high temperature wires installations will turn dark or brown after a short period of time in high temperatures. What does this color change indicate?

That the wax on the wire has become hot from ambient conditions. The wire is usually still clean and fully functional.

How do you know the switches motor rated?

Has FLA or HP marked on the switch

Why are motor rated switches needed?

To handle the higher motor starting amperage

Describe a pilot duty rated switch

Switch rated at 1 amp or less, or rated in VA

Describe a power duty rated switch

Switch with heavier contacts that can handle more than a couple amps

To be able to turn a light on or off at two separate locations what kind and how many switches are needed?

Two three-way switches

What does the letter B in the model number stamped on the side of an infinite which signify?

Broiler range switch

How does this broiler switch operate differently than a regular infinite switch?

More adjustment at the higher heat range of the curve

An immersion element that has the sheath split apart and swollen indicates what?

the unit ran dry or "dry fired"

What are stainless steel calrod elements normally used for in the foodservice industry?

Fryers

What usually causes the terminal connections to burn off the end of an element?

Loose or burned wire connections

How much current does a short circuit draw?

Infinite amps

If a circuit has two heating elements wired in series and each is rated at 120 V, what voltage must be supplied to the circuit in order for the elements to heat at full power

240V

What happens to current in a parallel circuit?

It's divides across the resistances

What happens to the voltage in a parallel circuit?

Its the same across all loads

What happens to current in a series circuit?

It is the same everywhere

What happens to the voltage in a series circuit?

It divides across the loads

In a parallel circuit the total resistance of the circuit will always be less than what resistance

The smallest resistance

In order for a receptacle to be properly grounded the ground wire must run where

all the way back to the panel

How much resistance should you read from a neutral to a ground?

0 ohms

Difference between neutral and ground

Neutral carries current ground does not

Mercury filled disarray assemblies are used for what temperature range thermostats

High temp

How can you tell if a thermostat is rated for pilot duty or power duty

Pilot duty is rated in VA or amperage less than 1 amp

Thermostats with steel diastats are normally used for what applications?

Ovens and ranges

Thermostats with nickel plated diastats are used for what applications in the foodservice industry?

Fryers

What is the switch arrangement on a Robertshaw EA thermostat?

SPST

What are the 3 different kinds of temperature sensors that can be used with a solid state control?

Thermocouple, thermistor, and RTD.