Wiring Diagram Tracing – Older RHEEM Condenser

Point-to-point diagrams illustrate how each component is wired in a piece of equipment; these tend to keep the same orientation as the physical piece of equipment. Conversely, a ladder schematic illustrates the current flow from one side of the circuit to the other (for example, from L1 to L2). Ladder schematics generally show the high-voltage side on top and the low-voltage side on the bottom.

Although diagrams can vary by manufacturer, there are typically a few consistent components. One of these is the presence of optional components on a point-to-point diagram. These components are NOT installed from the factory and are generally indicated by some variation of (OPT) on the point-to-point diagram. Field-installed components are connected by a dashed line, and factory-standard components are connected by a solid line.

All diagrams will have notes and a legend or component code to help you interpret the schematic. The legend will help you make sense of the abbreviations you see in the schematic. (For example, it will tell you that “CCH” means “crankcase heater” or that “CHC” means “crankcase heater control.”) Notes will give you information about acceptable connections and other relevant information for wiring the equipment.

On a ladder schematic, you will be able to determine the number of poles and throws of a component by looking at the diagram. A single-pole, single-throw component can only open or close. Squiggly lines underneath a component indicate a thermal switch, and a bell underneath a component indicates a pressure switch. A ladder schematic may or may not indicate the colors of the wires. If a ladder diagram does NOT show the colors, you may need to consult the point-by-point diagram.

A point-to-point diagram typically abbreviates the wire colors, so you may need to check the legend or notes. (For example, “R” may mean “red,” and “BK” may mean “black.”) Point-to-point diagrams may also indicate the placement of additional parts that would also be installed with optional components, such as wire nuts.

In short, ladder schematics show WHAT is connected, and point-to-point diagrams show HOW components are connected. The legends and notes exist to help you understand both diagram types.

If you have an iPhone, subscribe to our podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.