Basic Electricity. Wire Wire consists of: – A conductor Copper (CU) Copper-clad aluminum – Insulation Materials are based on the specific application.

Basic Electricity

Wire

• Wire consists of:– A conductor

• Copper (CU)• Copper-clad aluminum

– Insulation • Materials are based on the specific application• Designed to be non-conductive

Wire and Fuse Sizing

• Max fuse size• Minimum Circuit Ampacity (MCA)• Ground• Voltage drop• National Electric Code (NEC)

Wire and Fuse Sizing• High and low voltage wire not

allowed in same conduit

• Conductor or wire sizing is necessary to allow enough current to flow

• Sized by:• American Wire Gauge (AWG)• Amount of amperage permitted

to carry

• Types most commonly used:• THHN• TW

Fuses and Circuit Breakers• A fuse is the simplest form of

circuit protection. The word fuse derives from the Latin word meaning “to melt”

• Fuses have been used almost since electricity’s beginning. The earliest type of fuse that was used was a simple bare wire that was smaller than the conductor it was protecting, and therefore would melt before the conductor was harmed

Fuse Symbols

Screw-in style fuseCartridge Fuse

Circuit ProtectionPurpose of circuit protection:1. To protect the circuit wiring2. To protect the loads within the circuit

Protection from what:1. Direct shorts2. Excessive heat3. Excessive current

If these concerns are not protected, the possibilities are endless: fires, deaths, etc., which makes this issue a priority

Ratings

• Fuse Ratings• Current Rating• Voltage Ratings• Time Delay Rating

– Delay– Standard

Circuit Breakers

• It is called a circuit breaker because it breaks (opens) the circuit.

• The first compact, workable circuit breaker was developed in 1923.

• In 1928 the first circuit breaker was placed on the market.

Typical Residential Receptacles

Typical Romex Nomenclature

When wiring goes through a metal opening, it should be protected from wear by the use of plastic grommets, Romex connectors, or conduit connectors.

Number of insulated

wires

Wire Gauge

Cable type

Max. Voltage Rating

Paper

Typical Romex Nomenclature

Electrical boxes, furnaces, condensers, and disconnects all need connectors on high and low voltage wire to protect and to secure it

Cable Clamp

Cable Sheathing

Locknut

Wiring120 Volt Wiring(1) Black wire (Hot) potential(1) White wire (Neutral) potential(1) Bare or Green wire (Ground) safety!240 Volt Wiring(2) Black wires (Hot)(1) Black (1) Red wire (Hot)(1) Bare or Green wire (Ground) safety

240 VOLTIf using Romex with a Black and White

wire, tape the white insulation with black electrical tape to mark it as a hot wire.

When installing wires to switches, receptacles, thermostats, etc., loop the wire slightly and install the loop in the direction you will tighten screw. Only strip back wire enough to make a good connection. Leaving extra bare wire is dangerous!

Duplex Receptacle

Switch turns receptacle on and off

Receptacle stays hot. Switch turns appliance on and off

Wire Nut and Split Bolt

Split bolts can be used to join multiple high voltage wires.

High voltage wiring can be spliced together with split bolts

or wire nuts.

Typical Pictorial Diagram of a Condenser

• Wires must be in conduit• Conduit must have

connectors on both ends• Conduit must be strapped or

supported• Try to run conduit straight

and at 90 degree angles

Low Voltage Components

The air conditioning system is comprised of high voltage and low voltage circuits

What is a transformer?

Thermostats

Air Conditioner Thermostat Heater Condenser

Heat PumpThermostat Indoor Unit Outdoor unit

Color Code For Low Voltage Thermostat Wiring

Color Code For Low Voltage Thermostat Wiring

Relays• A relay is a device where current going into a coil creates a magnetic effect, which

switches one or more sets of contacts

• Different types of relays:• Control duty relays • Fan duty relays• Contactor relays

• There are 4 items you need to know about a relay or contactor:• Coil voltage• Contact voltage (maximum)• Contact amperage (maximum)• Contact type (S.P.S.T.; S.P.D.T.)

Fan CenterFan Center is a fancy name for a

transformer and fan relay mounted on a 4 x 4 cover plate that can be easily attached to a 4 x 4 gang box

They are primarily used with furnaces that were designed as heating-only systems (both gas and oil) that are being converted for use with air-conditioning

There is typically a wiring diagram available on the fan center