A Guide to Rocker Switches

Rocker switches are among the most familiar switch types you will encounter. The definition simply requires that the switching part of the mechanism rocks between two or more positions when pressed. As one end raises, the other lowers. They are also sometimes called see-saw switches.

Rocker switches can be contrasted with toggle or trip switches. With toggle switches, changing the switch position usually involves moving a small lever up or down, where it clicks into place. Rockers are not designed to move around in their housing this way. Instead, they just tilt back and forth around a central pivot point.

Choices of position for a rocker switch will often be limited to on/off, but some types may have three or more options to choose from. It is not uncommon for them to use a central off position, although switches with this feature tend to be more widely used in industrial settings as opposed to domestic ones.

As one of the most familiar switch types in the world, rocker switch uses cover a vast range of applications and devices. Most on-off power and light switches found around the home or office will be designed for a rocker or toggle-type operation, with rockers tending to be more common.

They are almost always seen on wall sockets, power outlets, surge protectors and extensions. They are also commonly used on many different sorts of standalone appliances and integrated electrical devices. You will often find illuminated rocker switches with embedded LEDs or similar, although this is by no means always the case - more often than not, basic off-on power rockers are non-illuminated.

Everyday usage examples include:

• Power supplies and control panels
• Household appliances, e.g. dehumidifiers and vacuum cleaners
• Medical equipment and machinery
• HVAC systems
• Hydraulic and pneumatic systems
• Vehicle electronics and dashboards - seat switches, electric windows, defoggers
• Fuse circuits

In most of these applications and many more besides, these switches are primarily chosen for their cost-effectiveness, convenience, and overall ease of operation. They tend to be somewhat wider than lever-type toggle switches, but do not usually stick out as far. They may feature illuminated areas with embedded LED lighting, often coloured red or orange to indicate active power flow.

This means that rockers can often be a better option if physical space is limited (particularly above or in front of the switch), or where it is preferable to keep them lower profile and less obtrusive. Miniature rocker switches are also sold for even smaller install locations. They also tend to be easier to clean around.

Rocker Switch Positions: Poles and Throws

We will take a closer look at several of the different types of rocker switch you can buy in the next section of this guide. Firstly though, it is worth taking a moment to clarify the terminology around rocker pole and throw types.

Most - though not all - are designed for controlling relatively simple circuits in a limited number of ways. They will often just give you the choice between on and off positions. If you need a more complex array of positioning and control options, you will often need to use something like a rotary switch.

Even so, regardless of which switch type you are buying, they will usually be sold according to the number of poles and throws they can switch between.

The most common configurations are:

• Single Pole, Single Throw (SPST)
• Single Pole, Double Throw (SPDT)
• Double Pole, Single Throw (DPST)
• Double Pole, Double Throw DPDT)

The circuitry of the devices or systems you are wiring up, and how you need to control them, will dictate which type of switch you need to buy.

Poles

Poles refer to the number of separate circuits the switch can complete (close) when it is switched in the ON positions. If a rocker delivers or interrupts power to just one circuit, it is a single-pole rocker switch, even if it has multiple ON positions (multi-throw). If it can control two separate circuits, either independently or together (via either one or two ON positions), it is a double pole switch. It can help to think of a double pole rocker as being able to perform the function of two single-pole switches, but from just one button.

Throws

Throws refer to the number of ON positions the switch can move between to close (power) the circuit(s) it is controlling. If it is a simple on-off rocker, it is known as a single throw switch, even if it closes more than one circuit at once (multi-pole). If it has two ON positions - for example, OFF, low power, and high power - it is a double-throw switch, even if it is only controlling a single circuit.

Switch Poles and Throws Examples

1. A desk fan has a single rocker switch that turns it either off or on. Because this rocker controls one circuit and has one ON position, it is a Single Pole, Single Throw (SPST) switch
2. A similar desk fan has a single rocker switch, but the rocker can select between off, low power, and high-power modes. Because this rocker controls one circuit and has two ON positions, it is a Single Pole, Double Throw (SPDT) switch
3. A hairdryer has a single rocker switch that turns it either off or on. When it is on, power is delivered to both the blower motor circuit and the heating element circuit simultaneously. Because this rocker controls two circuits and has one ON position, it is a Double Pole, Single Throw (DPST) switch
4. A similar hair dryer has a single rocker switch, but the rocker can select between off, low power, and high-power modes. Because this rocker controls two circuits and has two ON positions, it is a Double Pole, Double Throw (SPDT) switch

These switches are sold in many different formats and styles, which have different advantages and limitations in various applications and device types. Some of the most common variants are:

• On-off
• On-on
• Illuminated rocker
• Round rocker
• Power rocker
• Momentary
• Pushbutton
• Changeover
• Centre-off switch
• On-NONE-Off / On-NONE-On
• E-switch
• Miniature rocker switch (often sold in mm sizings)
• High inrush rocker switches

In the following sections, we will take a look at some of the above styles in more detail.

On-Off

An on-off (or off-on) switch allows the user to select between on and off positions for power delivery to one or more circuits simultaneously. Components sold as on-off rocker switches will typically have just those two positions available although you can also buy on-on versions for more specific applications.

Illuminated

Many rocker switches feature embedded illumination to show whether or not power is being sent to a circuit in a given position. These sorts of built-in LED indicators on illuminated rocker switches are especially common in applications like power strips and surge protectors. They are also widely found on dashboard displays, instrument panels and control arrays, as well as in some wall-mounted light switches and appliance breakers.

Momentary

Standard rocker switches latch into whichever position you press them into and remain engaged in that position until you switch them the other way. A momentary switch, however, is only engaged when pushed and returns to a default position when not being pressed. It usually does so with the aid of a built-in spring.

Momentary switches may be called push switches or non-latching switches. They can be designed as either normally on or normally off when in their default positions, although off is far more common. They are widely used on many types of intermittent input devices, from keypad controls to electric door and window mechanisms.

Changeover

A changeover or transfer switch (sometimes written as change over) is typically used to divert Voltage to or from one circuit to another. They are most often used in power supply and mains grid functions, allowing the user to select between one input source - for example, mains power - to a secondary source, such as a backup generator. They can be manual or automated. Some models may effectively function as two simultaneous circuit breakers, flipping in opposite directions in the same instance.

Centre-Off

Another type of rocker switch has a central OFF position. This usually means it will have (at least) two ON positions, typically at either side of the see-sawing mechanism. They may be called on-off-on switches, although centre-off is the preferred terminology, as it is less ambiguous. This type of switch can also be momentary, although in most cases they are designed for fully manual operation in all positions.