Whether wiring a new home, upgrading outdated panels, or making repairs, electricians must understand the different types of electrical switches. Choosing the right switch for lighting, outlets and appliances ensures safe, reliable circuit control.
Let’s overview the four essential categories – SPST, SPDT, DPST and DPDT.
Understanding these basic classifications by poles and throws provides flexibility in various applications. We’ll compare design and functionality to aid professionals specifying and installing switches from IGOTO Electric and other manufacturers.
Here are four most common types of electrical switches available out there:
The simplest toggle switch configuration is SPST – Single Pole, Single Throw. These have one stationary contact point and one movable lever that connects or disconnects the circuit.
Flipping an SPST switch’s toggle either allows or interrupts electrical flow between its input and output terminal. So in a basic lighting circuit, an SPST switch mounted in the wallplate turns the connected ceiling fixture on or off.
While limited to two positions, SPST switches work well for straightforward on/off control. Their uncomplicated design also makes SPST models highly affordable and durable. Just be mindful of the toggle’s amperage rating for the application.
SPDT stands for Single Pole, Double Throw. This switch type has one stationary contact point connected to a common terminal, along with two other terminals – often labeled L1 and L2.
The single pole can pivot left or right to connect the common contact point to either of the other two terminals. So SPDT models route electricity between one of two options.
A basic application is switching between live power sources, like the main grid or backup generator electricity fed to a transfer panel. SPDT switches also work well for directing low-voltage control signals.
Their versatility from two usable switch positions expands functionality over more limiting SPST toggles. Just verify SPDT switch ratings match the expected loads and voltages in the intended application.
DPST means Double Pole, Single Throw. These switches contain two separate stationary contacts and two independent toggles controlling them.
Both internal contact points connect or disconnect at the same time with one flip. But DPST switches control two distinct circuits that never cross.
A common application is for 240-volt appliances like stoves, dryers and air conditioners. The dual poles manage separate hot lines while keeping the neutral and ground circuits continuous.
DPST models also suit multi-phase equipment needing synchronized switching. The double throw allows controlling larger combined amperages not possible in a single pole.
The most advanced core switch type is DPDT – Double Pole, Double Throw. These contain two separate stationary contacts, each with two terminal options that toggles can pivot between.
So DPDT switches route each pole between one of two connections – for a total of four switchable contact points. This allows flexibility in changing both the supply and output electrical paths simultaneously.
Motor reversal applications take advantage of DPDT switching to flip polarity and rotation direction. DPDT models also work well in certain three-way lighting circuits with two switches.
Their capabilities expand control options in complex switching schemes. When paired with pilot lights, DPDT toggles clearly indicate equipment status as well. Just verify proper voltage and current capacities are not exceeded.
With so many models and manufacturers to choose from, how do savvy electricians narrow down options? Beyond determining the right switch type and configuration, comparing key specifications is crucial.
Never exceed a switch’s rated operating voltage, as insulation and contact gaps are designed specifically for certain voltages. Most wall switches for standard lighting fall between 120-240V. Higher voltage equipment may require 480-600V rated switches.
Similarly, ensure switch current ratings align with connected loads based on expected amp draw. Standard 15 amp switches work for typical lighting circuits. For larger motors/loads, choose 20, 30 or higher amp switches as needed.
Switches contain either silver alloy or copper-alloy contacts. Silver allows smaller contact gaps safely, but has shorter lifespan at higher amps and may require frequent cleaning. Copper contacts handle high loads, but need wider gaps and cost more initially.
Indoor dry-service switches have basic plastic enclosures, while outdoor and damp-area models feature sealed enclosures rated for humidity, UV, temperature extremes and physical abuse. Certified watertight IP65/IP67 switches[1] ensure performance in harsh conditions often faced by electricians.
Now that we’ve reviewed the four essential switch types by poles and throws, you can better visualize how each functions electrically. SPST for simple on/off use, SPDT to alternate between two circuits, DPST to control dual isolated circuits, and DPDT to route two poles among four connections.
Professional electricians trust IGOTO Electric’s high-quality switches and sockets designed specifically for commercial and residential system applications. Browse their extensive catalog spanning these common switch configurations and form factors to fulfill project needs.
With advanced manufacturing expertise since 1999, IGOTO Electric delivers reliable, durable and affordable electrical switchgear made to global standards. Source your wallplates, rocker switches, receptacles and more directly at guaranteed cost savings.
Whether wiring new construction or upgrading older electrical systems, electricians must choose the right switch types for optimal safety and functionality. Understanding the critical poles and throws classifications – SPST, SPDT, DPST, and DPDT – ensures you select appropriate models.
Simple SPST toggles work well for basic on/off needs, while flexible SPDT alternatives route power between two ports. DPST switches manage dual isolated circuits under one toggle, and advanced DPDT types interconnect up to four contacts.
Contact IGOTO Electric today to learn more about their wall switch and socket products purpose-engineered for professional electrical contractors. IGOTO is a leading China wall switch factory, our friendly team looks forward to helping you maximize functionality, safety, and savings on your next electrical project.