1.  E4 HVACR Electrical Installation #3 Circuit breakers, disconnects, and fuses

2.  2 HVAC Installation The following diagram shows that several different voltages could be used in one installation: –240 volts for the condensing unit –120 volts for the air handler or gas furnace – 24 volts for the control circuit

3.  3 HVAC Power Needs in a Home 70 80 60 50 60 50 70 80 Service Entrance Condensing Unit A/C Disconnect Electric Panel Furnace Disconnect Thermostat Furnace 240 Volts 120 Volts Control Wiring 24 Volts

4.  4 Single Phase Electric Panel The following drawing shows how circuit breakers access the incoming power

5.  5 Electric Panel Main Breaker Bus Bars Neutral Ground Main Power 240v / 120v -1Ø Double Pole Circuit Breaker 240v 240v Circuit 120v Circuit Single Pole Circuit Breaker 120v

6.  6 Disconnects The electrical code requires a safety switch at the equipment to disconnect power if necessary

7.  7 Indoor Disconnect heat pump air handler Safety switch with a circuit breaker for a

8.  8 Outdoor Safety Switch / Disconnect Courtesy of Carrier

9.  9 Different Types of Disconnects Some disconnects are just switches Some are switches with circuit breakers or fuses Some are “pull-outs” that may or may not be fused

10.  10 “Pull-out” Fused Disconnect

11.  11