Electrical Principals Chapter 5 Switches, Fuses, Ground, Receptacles, Basic Circuit Conditions.

Electrical PrincipalsElectrical PrincipalsChapter 5Chapter 5

Switches, Fuses, Ground, Switches, Fuses, Ground, Receptacles, Basic Circuit Receptacles, Basic Circuit

ConditionsConditions

SwitchesSwitches

SwitchesSwitches

A A SwitchSwitch is a device that is used to start, stop, is a device that is used to start, stop, or redirect the flow of electricity in an electrical or redirect the flow of electricity in an electrical circuit.circuit.

A A SwitchSwitch must be rated higher than (or equal to) must be rated higher than (or equal to) the voltage and current the the voltage and current the SwitchSwitch is controlling. is controlling.

There are three manual types of There are three manual types of SwitchesSwitches used used to control the ON/OFF current flow in a circuit to control the ON/OFF current flow in a circuit and they are two-way, three-way, and four-way and they are two-way, three-way, and four-way switches.switches.

SwitchesSwitches

Two-Way SwitchTwo-Way Switch is a single-pole, single- is a single-pole, single-throw (SPST).throw (SPST).

A A Two-Way SwitchTwo-Way Switch has two positions and has two positions and they are ON and OFFthey are ON and OFF

A A Two-Way SwitchTwo-Way Switch is used to control a is used to control a circuit from one location.circuit from one location.

SwitchesSwitches

Three-Way SwitchThree-Way Switch is a single-pole, is a single-pole, double-throw (SPDT) switch.double-throw (SPDT) switch.

A Three-Way SwitchA Three-Way Switch does not have an does not have an ON – OFF position.ON – OFF position.

A A Three-Way SwitchThree-Way Switch is used to control a is used to control a circuit from two different locations.circuit from two different locations.

SwitchesSwitches

A A Four-Way SwitchFour-Way Switch is s double-pole, is s double-pole, double-throw (DPDT) switch.double-throw (DPDT) switch.

A A Four-Way SwitchFour-Way Switch changes the changes the electrical connections inside the switch electrical connections inside the switch from straight to diagonal.from straight to diagonal.

A A Four-Way SwitchFour-Way Switch does not have ON – does not have ON – OFF positions.OFF positions.

A A Four-Way SwitchFour-Way Switch is used with Three- is used with Three-Way switches to control a circuit from Way switches to control a circuit from three different locatrions.three different locatrions.

SwitchesSwitches

FusesFuses

FusesFuses

A FuseA Fuse is an equipment protection device that is an equipment protection device that consists of a thin wire link within a casing.consists of a thin wire link within a casing.

All All FusesFuses have a current rating and this have a current rating and this indicates what value of current will generate indicates what value of current will generate enough heat to open the enough heat to open the FuseFuse..

When the circuit current exceeds the rating of When the circuit current exceeds the rating of the fuse, the fuse opens (wire link melts) and the fuse, the fuse opens (wire link melts) and prevents current from flowing in that part of the prevents current from flowing in that part of the circuit.circuit.

FusesFuses

Fuses Fuses come in a variety shapes, sizes,come in a variety shapes, sizes,

FusesFuses are very low resistance devices are very low resistance devices connected in series with the circuit’s connected in series with the circuit’s conductors.conductors.

FusesFuses for DC current are different from for DC current are different from FusesFuses used in AC circuits. used in AC circuits. Fuses Fuses ARE ARE NOTNOT Interchangeable between AC and Interchangeable between AC and DC circuits.DC circuits.

FusesFuses

FusesFuses also have a voltage rating that indicates also have a voltage rating that indicates the maximum circuit voltage that can be applied the maximum circuit voltage that can be applied across the across the FusesFuses by the circuit in which the by the circuit in which the FusesFuses resides. resides.

This voltage rating, which is important after the This voltage rating, which is important after the fuse has blown, prevents arcing across the fuse has blown, prevents arcing across the blown fuse contacts.blown fuse contacts.

Once the fuse has blown, the circuits positive Once the fuse has blown, the circuits positive and negative voltages are now connected and negative voltages are now connected across the fuse contacts.across the fuse contacts.

FusesFuses

If the voltage is too great, an arc can jump If the voltage is too great, an arc can jump across the gap, causing a sudden surge of across the gap, causing a sudden surge of current, damaging the connected equipment.current, damaging the connected equipment.

FusesFuses are mounted with are mounted with FusesFuses holders and holders and normally are placed at the back of the equipment normally are placed at the back of the equipment for easy access.for easy access.

When replacing When replacing FusesFuses ensure the power to the ensure the power to the equipment is turned OFF before replacing a equipment is turned OFF before replacing a blown blown Fuses.Fuses.

GroundGround

GroundGround

GroundGround is a term used to identify zero potential. is a term used to identify zero potential. All potentials are either positive or negative with All potentials are either positive or negative with respect to ground.respect to ground.GroundGround, in electricity, is an electrical conductor , in electricity, is an electrical conductor that is connected to Earth to complete a circuit. that is connected to Earth to complete a circuit. In electrical equipment, such as household In electrical equipment, such as household appliances, the ground conducts electric current appliances, the ground conducts electric current that may build up in the appliance because of a that may build up in the appliance because of a "leak" or a short circuit. "leak" or a short circuit. There are two types of There are two types of Grounds: Earth and Grounds: Earth and Electrical.Electrical.

GroundGround

In homes, offices, and buildings or AC circuits, In homes, offices, and buildings or AC circuits, all electrical circuits and appliances are earth all electrical circuits and appliances are earth grounded.grounded.

In automobiles, the chassis becomes the ground In automobiles, the chassis becomes the ground for all circuits. The ground serves as part of the for all circuits. The ground serves as part of the complete circuit.complete circuit.

In electronics, electrical ground serves a In electronics, electrical ground serves a different purpose: different purpose: GroundGround is defined as the zero is defined as the zero reference point against which all voltages are reference point against which all voltages are measured.measured.

ReceptaclesReceptacles

Basic Circuit ConditionsBasic Circuit Conditions