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

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
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

3. HVAC Power Needs in a Home
Thermostat 70 80 60 50
Service Entrance
Furnace Disconnect
Electric Panel
A/C Disconnect
Furnace
240 Volts
Condensing Unit
120 Volts
Control Wiring 24 Volts
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

4. Single Phase Electric Panel
The following drawing shows how circuit breakers access the incoming power
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

5. Electric Panel Main Power 240v / 120v -1Ø Main Breaker
Double Pole Circuit Breaker 240v
Bus Bars
240v Circuit
Single Pole Circuit Breaker 120v
120v Circuit
Neutral
Ground
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

6. Disconnects
The electrical code requires a safety switch at the equipment to disconnect power if necessary
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

7. Safety switch with a circuit breaker for a
Indoor Disconnect
Safety switch with a circuit breaker for a
heat pump air handler
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

8. Outdoor Safety Switch / Disconnect
Courtesy of Carrier
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

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
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

10. “Pull-out” Fused Disconnect
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1

11. End of Circuit Breakers, Disconnects, and Fuses
© 2005 Refrigeration Training Services - E4#3 Circuit Breakers, Disconnects, and Fuses v1.1