Principles of Electricity 6831 16 Volt The measurement

Principles of Electricity 6831. 16

Volt • The measurement of electrical pressure

Ampere • The rate of flow of electricity

Watt • The measurement of electrical power

W=Vx. A • Watts equal volts multiplied by amps

W=Vx. A • This formulas is sometimes called the West Virginia formula

W=Vx. A • How many watts of electricity will a 7. 5 ampere electric motor use in 5 hours on a 120 volt circuit • W=120 x 7. 5 x 5 W=4500

V = W/A • Volts equal watts divided by amps

V = W/A • What volt circuit is needed for an 7. 5 amp electric motor that uses 900 watts in one hour • V=900/7. 5 V=120

A = W/V • Amps equal watts divided by volts

A = W/V • What should the amp rating of an electric motor be if it uses 900 watts of electricity in one hour in a 120 volt circuit • A=900/120 A=7. 5

Kilowatt • 1000 watts

Cost of Electricity • Cost per kilowatt x number of kilowatts x hours of use

Cost of Electricity • If electricity costs 12 cents per kilowatt hour, how much would it cost to use 2 kilowatts per hour for 10 hours • . 12 x 10 = $2. 40

I = E/R • Ohm’s Law • Amps (I) = Volts (E) divided by Resistance (R)

Circuit Breaker • Protects circuits form overload of current by tripping to break or open the circuit

Circuit breaker

Fuse • Protects circuits from overload by melting a metal strip in the fuse

Conductors • Materials such as copper, aluminum, or water that will carry or conduct electricity

Insulators • Materials such as rubber and plastic that will not conduct electricity

Hot Wire • A current carrying conductor under electrical pressure

Neutral Wire • A current carrying conductor not under electrical pressure (has volts)

Ground Wire • A conducting wire that transmits current to the earth to minimize the danger of electrical shock

Formulas to Compute Electrical Energy and Cost

Organizations • National Fire Protection Association (NFPA) promotes and improves the science and methods of fire protection and publishes the National Electric Code (NES)

Organizations • Underwriter Laboratories (UL) tests all types of wiring materials and electrical devices for safety

Safety Precautions • Wear boots or shoes with rubber heels to insulate against shock

Safety Precautions • Wear clothing made of materials low in flammability to prevent fires

Safety Precautions • Ground all outlets, switches, service entrances to prevent shock

Solderless wire nut

Safety Precautions • Extension cords should not be used under carpet because of fire danger

Safety Precautions • Extension cords should not be used under carpet because of fire danger

Safety Precautions • Standing in water or damp places or touching switches or receptacles with wet hands may cause electrical shock because water conducts electricity

Safety Precautions • Do not touch someone undergoing electrical shock because both people will become part of circuit, and both will be shocked

Safety Precautions • Always turn circuit breaker to “off” position before beginning work

Safety Precautions • Use correct size fuses and circuit breakers to prevent fires

Safety Precautions • Use only double insulated portable tools or those with three wire grounded cords to prevent shock

Safety Precautions • The two deadliest hazards associated with electricity are shock and fire

Safety Precautions • Precautions and common sense should be used to prevent conditions that will cause either

Principles of Electricity 6831. 16