SPST switch? SPDT switch? DPST switch? DPDT switch? Whoa – pump the breaks. What do all those letters stand for? What do these electrical switches do?
Let’s start with some basics.
How does a switch work?
An electrical switch always has a few different ratings: amperage, voltage, and type of voltage.
Amperage is the measurement of the flow of electricity through a circuit, and is abbreviated as “amps” (A).
Voltage is the measurement of electrical pressure required to create the movement or flow of electricity through a circuit, and is abbreviated as “volt” (V). Voltage can either be AC or DC.
AC voltage simply means
“alternating current”, which means the electric current (or voltage) reverses direction at consistent intervals. AC voltage is often found in things such as a wall outlet.
DC voltage, or “direct current”, refers tothe current of electricity maintaining its direction. DC voltage has either a positive or negative polarity which it maintains. DC voltage is often found in vehicle applications or batteries.
Although it’s not often, there are times when a switch is rated with Horsepower, which is defined as 1HP = 746 Watts of electrical power.
Now that we have a better understanding of the ratings which an electrical switch operates within, let’s consider what the actuation of a switch means for your application.
Types of Electrical Switch Actuation Configurations
SPST switch stands for a single pole single throw electrical switch. A SPST switch controls a single wire circuit.
- Example: ON – OFF
SPDT switch stands for a single pole double throw electrical switch. A SPDT switch controls two single wire circuits, with only one circuit able to be energized at a given time.
- Example: ON – OFF – ON
DPST switch stands for a double pole single throw electrical switch. A DPST switch controls two circuits at the same time; either both circuits are ON or both circuits are OFF. However, it is possible to have different voltages from separate sources wired to one DPST switch.
- Example: ON – OFF
DPDT switch stands for a double pole double throw electrical switch. A DPDT switch controls four circuits, allowing two of the four circuits to be energized at the same time. Similar to the DPST configuration, the two circuits which are energized will either both be ON or both be OFF, and can have different voltages from separate sources wired to one DPDT switch.
- Example: ON – OFF – ON
This terminology is consistent across the different types of electrical switches including toggle switches, rocker switches, and push button switches. These actuations can also be momentary, meaning the actuation only occurs while the switch is being held in a specific position. Momentary action is designated differently across the industry, but at Del City, we indicated momentary action by ( ).
To learn more about electrical switch configurations and common uses, watch the video below! Or, start searching for your switch by using our electrical switch selector!