2 Wire Wire consists of: A conductor Insulation Copper (CU) Copper-clad aluminumInsulationMaterials are based on the specific applicationDesigned to be non-conductive
3 Wire and Fuse Sizing Max fuse size Minimum Circuit Ampacity (MCA) GroundVoltage dropNational Electric Code (NEC)
4 Wire and Fuse SizingHigh and low voltage wire not allowed in same conduitConductor or wire sizing is necessary to allow enough current to flowSized by:American Wire Gauge (AWG)Amount of amperage permitted to carryTypes most commonly used:THHNTW
5 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 harmedFuse SymbolsScrew-in style fuseCartridge Fuse
6 Circuit ProtectionPurpose of circuit protection: 1. To protect the circuit wiring 2. To protect the loads within the circuit Protection from what: 1. Direct shorts 2. Excessive heat 3. Excessive current If these concerns are not protected, the possibilities are endless: fires, deaths, etc., which makes this issue a priority
7 Ratings Fuse Ratings Current Rating Voltage Ratings Time Delay Rating Standard
8 Circuit BreakersIt 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.
10 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 wiresCable typeMax. Voltage RatingPaperWire Gauge
11 Typical Romex Nomenclature Electrical boxes, furnaces, condensers, and disconnects all need connectors on high and low voltage wire to protect and to secure itLocknutCable ClampCable Sheathing
12 Wiring 120 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) safety240 VOLTIf using Romex with a Black and White wire, tape the white insulation with black electrical tape to mark it as a hot wire.
13 When installing wires to switches, receptacles, thermostats, etc 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!
14 Duplex Receptacle Switch turns receptacle on and off Receptacle stays hot. Switch turns appliance on and off
15 Split bolts can be used to join multiple high voltage wires. Wire Nut and Split BoltHigh voltage wiring can be spliced together with split bolts or wire nuts.Split bolts can be used to join multiple high voltage wires.
16 Typical Pictorial Diagram of a Condenser Wires must be in conduitConduit must have connectors on both endsConduit must be strapped or supportedTry to run conduit straight and at 90 degree angles
17 Low Voltage Components The air conditioning system is comprised of high voltage and low voltage circuitsWhat is a transformer?
18 Thermostats Air Conditioner Heat Pump Thermostat Heater Condenser Thermostat Indoor Unit Outdoor unit
21 RelaysA relay is a device where current going into a coil creates a magnetic effect, which switches one or more sets of contactsDifferent types of relays:Control duty relaysFan duty relaysContactor relaysThere are 4 items you need to know about a relay or contactor:Coil voltageContact voltage (maximum)Contact amperage (maximum)Contact type (S.P.S.T.; S.P.D.T.)
22 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 boxThey are primarily used with furnaces that were designed as heating-only systems (both gas and oil) that are being converted for use with air-conditioningThere is typically a wiring diagram available on the fan center