SOC Basic Electricity Flashcards
What is the purpose of panel boxes and breakers?
Divides an electrical power feed into subsidiary circuits, while providing a protective fuse.
- What color is used for neutral wire?
White
* if neutral wire is used as hot wire, recode with electrical tape
- What frequency is used outside of United States
50 Hz
- What is Watts?
The amount of energy consumed at a given point. It represented “W”
- What are some examples of circuit protection devices?
Fuses and Circuit Breakers
- What is bonding?
The permanent joining of metallic parts to form an electrically conducting path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.
To establish an effective path for fault currentThe earth shall not be considered as an effective ground-fault current path
- What are some load sources?
Panel box
end of circuit receptacle
switch loop
junction box
- How deep grounding must be?
Must have 8 feet in ground, below the permanent moisture level
- What is Amperage?
The rate of electrical current flow. It represented “A”
- How to convert kilowatts to watt?
Kilowatt multiply by 1000.
1 kilowatts = 1000 watts
- Determine combined Amps
List all appliances, fixtures and their wattage, amps, kilowatts, volts, or horsepower (1hp=750w)
Add total wattage divide by 120/240 volts = Amps
Calculate for continuous load, i.e. 80% rule applies. • Examples, Total wattage is 17201720 /120 volts = 14.333 amps One 20 amp circuit
- What are the five factors influencing the effect of an electric current passing through a human body?
Frequency (60 hz is worst) Current frequency Voltage Body contact resistance Internal body resistance
- What are the main causes of Electrical Shock?
Wear and tear Defective construction Misuse of equipment Insulation failure (Insulation failure can result when the Hot ungrounded conductor on the appliance comes in contact with the metal frame of the appliance)
What are the signs of voltage drop?
Dimming lights Television pictures shrink Motors run hot Reduced heater output Improper appliance operation
- What is purpose of nail guard?
To prevent nail penetration directly into wires
- What are correct heights for the placement of various electrical boxes?
48” switch box
42” Receptacle over a counter
36” Washer/Dryer receptacle
12” Receptacle box in living area
- List some Electrical Safety Considerations
Wear rubber soled shoes
Use Fiberglass or wood ladders near electrical wires
Make sure the circuit is disconnected from its power source
Use proper circuit testers to ensure the circuit is dead
Treat all electrical circuits as live
Use fuse pullers for removing and replacing fuses
Avoid clothing with metal zippers or fasteners
Do not wear dog tags
Roll shirt sleeves down
- What are the two types of Electricity?
1) DC
Direct current, the electricity flowing in a constant direction.
Ex) Batteries, static and lightning
2) AC
Alternating current, the electricity repeatedly changes its direction.
Ex) Generator made, it’s a frequency measured in cycles per second, Hertz.
- What is the West Virginia Formula?
Watts = Voltage x Amps Volts = Watts / Amps Amps = Watts / Volts
- What is HP?
It is horsepower. One electrical horse power equals 750 watts.
- Describe typical usage for circuits based on amperage
20 amp: Small appliances and lighting
30 amp: Dryer, cook tops, and shall not exceed 80% of load
40-50 amp: Cooking equipment, electric ranges, water heaters
Over 50 amp: Electric furnaces, large heat pumps, air-conditioning equipment and larger loads
- What is Hertz?
A hertz is the measurement of electrical frequency, with 1 Hz being one cycle per second.
- What is Volts?
Voltage or volt is potential to do operate electric device
ie 110V
- What defines continuous load?
Maximum current expected to continue for three hours or more
- What are the parameters of a grounding rod?
Diameter 1/2 inch
No less than 8 feet in length
In ground at least 8 ft
Top flush with ground
- What calculation rule could you use for planning ?
Use 3 Watts per square foot
Examples, 2582 sq ft x 3 watts = 7746 watts 7746/120 = 64.55 amps 64.55x1.25 = 80.68 amps Can divide by smaller amps circuits to find how many
- What is Ohm’s law?
It defines the relationships between: (P) Power (E) Voltage (I) Current (R) Resistance
- What are the three different sizes of main panel box?
100, 150, 200 AMPS
- What is the 2’/4’ rule?
In the kitchen, receptacles need to be no more than 4’ apart along countertops (appliance wires are usually 2’ long)
- What do we need to know in order to make circuit calculations?
Number of loads on the circuit Wattage of each load Amperes required Voltage required The distance from the service panel to the load
- What color of sheathing is used for 10ga wire?
Orange for 30 Amp circuits
- What tool should you use for removing and replacing fuses?
Fuse puller
- What is the 80% rule?
Never go more than 80% amps for the circuit. Continuous load = maximum current expected to continue for three hours or more.
- What color of sheathing is used for 14ga wire?
White for 15 Amp circuits
- What is an insulator and what can be used as insulator?
Insulators slow or stop the flow of electricity.
Glass, plastic, rubber, and anything that is considered a non-conductor could be used as insulator.
- What happens when exposed to electricity?
Faint tringle, shock, and potential to die.
- What causes voltage drop and how much does it drop over distance?
Wires too small for load being served
A circuit that is too long- Poor connection at the terminal
Conductors operating at high temperatures
10 ft = 3 Volts
100 ft = 10 Volts
- What color of sheathing is used for 12ga wire?
Yellow for 20 Amp circuits
- What frequency is used in United States?
60 Hz
- What colors are used for hot wire?
Red/Black (3 wire)
Black (2 wire)
- What colors are used for grounding wire?
Copper (2/3 wire)
Or green
- What does transformer do to electric current?
Transformers can turn a lower voltage into a larger one and vice versa. Also known as an Amplifier. (Step-up, Step-down)
- Before testing a circuit, what tester must do?
Ensure that circuit is “DEAD”
- Describe wire gauges and their appropriate amperage
14 gauge = 15 Amps 12 gauge = 20 Amps 10 gauge = 30 Amps 8 gauge = 40 Amps 6 gauge = 50 Amps 3 gauge = 100 Amps 1/0 gauge = 150 Amps 3/0 gauge = 200 Amps
- What is grounding
Intentionally creating a low distance path connects to the earth. A secondary protective measure
- What is the 6’/12’ rule?
For every 12’ of living room wall, a receptacle is needed to accommodate 6’ appliance cords
What is the panel box?
Only place where all power can be cut off at once. Distribution point and protection center for all circuits.
What are the four main types of electrical injury?
Direct 1) Electrocution (or death due to electrical shock) 2) Electrical shock 3) Burns Indirect 4)Falls
When does the hazard of shock exist?
When in contact with both the defective equipement and a grounded surface such as:
Water pipes
Stainless steel sinks
Metal faucets
Grounded luminaries (fixtures)
Earth
Concrete in contact with the earth or water
Voltage fluctuation in common circuits
110-120v
220-240v
Resistance
Resistance( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.
Power
Power is the amount of current times the voltage level at a given point measured in wattage or watts.
Current
Current is what flows on a wire or conductor like water flowing down a river. Current flows from negative to positive on the surface of a conductor. Current is measured in (A) amperes or amps.
Voltage
Voltage is the difference in electrical potential between two points in a circuit. It’s the push or pressure behind current flow through a circuit, and is measured in (V) volts
Where is electricity trying to flow to?
Back to the source of its creation
Ground Gauge (Copper) Service Size
#8 to 100A #6 to 125A #4 to 165A #3 to 200A
What needs bonding?
Non-current-carrying conductive materials shall be connected to the supply source to make an effective ground-fault current path
Anything likely to become energized
Types of breakers
Single Pole
Double Pole
How to reset a breaker
Popped means it will be in the central position, go all the way off, then back on
What is 1 HP in Watts
750 Watts
What shall circuit load not exceed?
Branch circuit rating
Wire Gauge, Amps and Maximum Wattage Load
14 G, 15 Amps, 1440 W (120V)
12 G, 20 Amps, 1920 W (120V) 3840W (240V)
10 G, 30 Amps, 2880 W (120V) 5760W (240V)
8 G, 40 Amps, 7680 W (240V)
6 G, 50 Amps, 9600 W (240V)
What are the appropriate electrical box heights?
48” switch box
42” Receptacle over counter
36” Washer/dryer receptacle
12” Receptacle in living area
How far should wire extend beyond the receptacle when installing?
6”
How much excess cable should there be before a receptacle?
6-8”
How are wires secured to studs?
Wire staples, 5/8 hole at least 1 1/4” from front of stud
How far apart should wire staples be in general?
4’
How far after a receptacle should there be a wire staple?
8”
What should you do to wires before splicing with wire nuts?
Twist the strands together
Types of switches?
Single Pole
Two Pole
Three Way
Four Way
What is an Ohm?
One ohm is the resistance value through which one volt will maintain a current of one ampere.
