The local power company supplies the power necessary for operation to what is known as the high voltage side of the HVAC unit. A contactor is present in the HVAC unit to allow the flow of electricity from the service breaker to the unit itself. It is quite literally what enables the HVAC unit to run.
The power company sends electricity at a very high voltage through power lines. These power lines typically run above the roads or through piping underground.
First, the energy travels from the power lines to a transformer. The transformer takes the high voltage electricity and lowers it to safe levels for common electrical applications. From the transformer, the electricity heads to a specific building.
Next, the power hits the building meter which measures how much electricity is used by a specific facility, and how much the power company needs to bill the occupant.
After the building meter, the electricity enters a service breaker. The service breaker distributes the electricity into smaller subsections of the building. HVAC units and other areas of high energy consumption frequently have dedicated circuit breakers on the service breaker. From here, electric wires leave the service breaker and head to the HVAC unit.
There is a service disconnect lever that cuts off all power entering the unit. If the service disconnect is not pulled, the unit should receive enough power to operate. The service disconnect is in place as a safety precaution to ensure a servicing technician can safely work on the HVAC unit.
