Basic Electricity

1. Basic Electricity

2. A circuit needs 3 things • Source – voltage 240v, 120v, 24v, etc • Path – wire, switches, thermostat • Load – contactor coil, 1 motor, compressor, etc

3. Two Basic Types of Circuits • Series • Parallel

4. Wire • Wire consists of: • A conductor • Aluminum (AL) • Copper (CU) • Copper-clad aluminum • Insulation • Materials are based on the specific application • Designed to be non-conductive • Rules of Sizing Wire

5. Wire and Fuse Sizing Max fuse size Minimum Circuit Ampacity (MCA) Ground Voltage drop National Electric Code (NEC)

6. 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

7. 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 fuse Cartridge Fuse

8. Circuit Protection Purpose 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

9. Ratings • Fuse Ratings • Current Rating • Voltage Ratings • Time Delay Rating • Delay • Standard

10. Checking and Replacing Fuses • Checking an open fuse • Visual Inspection • Checking fuses with a meter • Safety precautions when checking a fuse • Replacement of fuses • Proper fit of replacement fuses

11. 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.

12. Typical Residential Receptacles

13. 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 Cable type Max. Voltage Rating Paper Wire Gauge

14. Typical Romex Nomenclature Electrical boxes, furnaces, condensers, and disconnects all need connectors on high and low voltage wire to protect and to secure it Locknut Cable Clamp Cable Sheathing

15. 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) safety 240 VOLT If using Romex with a Black and White wire, tape the white insulation with black electrical tape to mark it as a hot wire.

16. 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!

17. Typical Pictorial Diagram for Gas Furnaces Note: A good ground wire is needed all the way back to the main panel to have the newer furnace circuit boards operate properly.

18. Duplex Receptacle Switch turns receptacle on and off Receptacle stays hot. Switch turns appliance on and off

19. Wire Nut and Split Bolt High voltage wiring can be spliced together with split bolts or wire nuts. Split bolts can be used to join multiple high voltage wires.

20. Electric Heat Strips Normally, heat strips are rated in 5 KW strips (5000 watts). A 5 KW strip would require a 30 amp, 230 volt breaker. A 10 KW circuit ( (2) 5 KW strips) would require a 60 amp, 230 volt breaker. So... • A 5 KW blower coil would require: 30 amp breaker, #10 wire • A 10 KW blower coil would require: 60 amp breaker, #6 wire • A 15 KW blower coil would require: 30 amp breaker, #10 wire AND 60 amp breaker, #6 wire • A 20 KW blower coil would require: (2) 60 amp breakers AND (2) sets of #6 wire

21. Typical Pictorial Diagram of a Condenser

22. Wiring Condensers • 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 DO Disconnect Condenser Run conduit at 90 degrees. Neat!

23. Wiring Condensers DON’T • Do not run conduit too short or “cut across” • Do not leave excess conduit in place. Too much excess looks tacky. • Do not let conduit lay on the ground How neatly you work directly reflects on you and your company. Disconnect Condenser Conduit too short, not supported to wall DON’T Disconnect Condenser

24. Typical Load Voltages 120v Single Phase

25. 240v Single Phase

26. Low Voltage Components The air conditioning system is comprised of high voltage and low voltage circuits What is a transformer?

27. Common Electrical Symbols

28. Thermostats Air Conditioner Thermostat Heater Condenser Heat Pump Thermostat Indoor Unit Outdoor unit

29. Color Code For Low Voltage Thermostat Wiring

30. Color Code For Low Voltage Thermostat Wiring

31. Color Code For Low Voltage Thermostat Wiring

32. 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.)

33. Fan Center Fan Centeris 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

34. Basic Furnace Wiring Schematic

35. Basic Condensing Unit Wiring Diagram (dual run capacitorP.S.C. Capacitor Start Capacitor Run (CSCR)

36. PSC Capacitor Start Capacitor

37. Meters Settings and Use When checking voltage and amperage, start by setting the meter to a scale higher than the expected value. The setting can then be lowered for a more accurate reading once the value is known. This is not necessary with auto-ranging meters.