Product Manager at Honeywell
Bryan has been a product manager at Honeywell for 8 years and managed several sensor and switch products. He has a BS in electrical engineering from the Pennsylvania State University and an MBA from the Edinburgh Business School at Heriot-Watt University, Edinburgh, Scotland. He started his professional career as an R&D engineer with Hewlett-Packard before moving to the dark side and joining marketing in 1987.
oggle switches aren’t complicated, but to make sure you get years of reliable performance, make sure you consider these 7 factors when choosing a toggle switch.
A guide to selecting panel-mounted toggle switches
Panel-mounted toggles switches are a common user interface. The operation is similar across many manufacturers: the actuator (lever) moves contacts within the switch to make or break the electrical circuit.
Why use a toggle switch?
Toggles may seem a rather old-fashioned user interface. However, while many alternative solutions exist, toggles still have many advantages, making them the ideal choice in many applications.
A properly designed panel-mounted toggle is very robust and can tolerate significant mistreatment. This can make it preferable to more sophisticated solutions such as touchscreens. It is also easy to see or even feel the state of a toggle. This makes toggles ideal for operating heavy machinery, for instance.
Toggles can often switch high currents so they can be used to directly control equipment. Other types of controls may only handle low current levels and require additional interface circuitry. Using toggles can create simple, intuitive control systems.
It is also possible to design toggles to be tolerant of vibration and contamination by debris or water.
Finally, should a toggle fail or be damaged, it is a quick operation to replace the switch and get the asset it controls back into service. It isn’t uncommon for damage to other types of control systems to take equipment out of service for days or weeks and to require expensive replacement parts and specialised technicians to recommission.
7 considerations for choosing the right toggle switch
When you select a toggle, you might be tempted to think it’s just a toggle switch – flip the lever to change state, simple. But while it isn’t especially complicated, it’s worth taking into account a few considerations to make sure you get years of reliable performance from your toggle switch.
1. Where and how will you use the switch?
The operating conditions will be the first consideration. If it is a controlled environment, with no risk of contamination or moisture ingress, an unsealed switch could be sufficient.
Also, if you will only use the switch occasionally, with an ungloved hand, and if you don’t expect to have to replace it during the lifetime of the equipment, then a low-cost PCB mounted switch may be the best choice.
If there is higher risk of exposure, being used outdoors or in a dirty or dusty area, a sealed product would provide greater reliability. If you will use the switch in an agricultural or construction environment, or in any situation where the operator tends to wear gloves, panel-mounted switches are often the best choice and are the most easily replaced in the event of damage.
Many panel-mounted toggle switches are sealed around the lever. This protects them from ingress originating from the front of the control panel. However, in many environments the switch may be subject to ingress behind the panel. Care should be taken to verify that the switch has the required sealing both at the front and at the back of the switch and whether the sealing requires the use of sealing washers to prevent ingress around the threads from the front to the back of the panel.
The degree of ingress protection is also critical. A switch may be exposed to no more than occasional splashing, or it may have to be able to resist submersion. One of the most challenging situations is jet washing. Jet washers, whether or not they are recommended, are often used on construction and agricultural equipment and can easily lead to water ingress into a toggle.
The seal provided to protect against water ingress can be damaged by dirt and debris, so it is common to provide secondary sealing using either a full or half boot to protect the seal at the base of the lever.
Toggle switches can be exposed to severe vibration in most traditional applications, and a well-designed toggle will be unaffected by the vibration. However, in cases of very severe vibration, a toggle connection may become intermittent and the lifetime of the switch may be shortened. In these cases it is often prudent to consider a mil specified toggle, which is designed to tolerate much more demanding environmental conditions.
As toggles are a user interface, the temperature and humidity will generally be limited to what the user finds tolerable. However, because of conducted heat, exposure to the sun, high temperatures during storage or because the switch is may be located in a hostile environment not normally accessed by an operator, care must always be taken to check the toggle switch is compatible with the temperature, humidity and other environmental conditions it will experience.
2. What features do you need to control?
Flipping the lever can cause a range of actions. Do you want to go from one active circuit to another active circuit (On-On), or have the switch hold in the off state and only activate when the operator holds the lever in the on state (Off-Momentary On), for example?
There are sequences of events that can be catered for. The data sheet of the toggle switch will list the available configurations such as those shown in this table:
|Keyway side (1-2)||Centre (1-2)||Opposite keyway (2-3)|
|MOM ON||OFF||MOM ON|
3. What is the best contact material?
The choice of contact material must take into account the current the switch will handle.
Panel-mounted toggle switches can generally handle significant currents. This means motors, lights and other loads can often be directly driven through the switch, which can simplify machine design. However, it may also be desirable to have the toggle handle low-level signalling currents.
Silver would be best for higher current loads, but would be at risk or tarnishing if left for a period of inactivity. However, in high-current applications this doesn’t present a problem.
Gold contacts would be less inclined to tarnish and more resistive to any surface contamination, but could burn away if loads higher than data signal level (i.e. 100mA) are being carried.
4. What is behind the panel?
Levers and bushing from the front can look similar, but a variety of case styles are available behind the panel. If there is to be a high density of toggles on the panel, it may be advantageous to use a miniature toggle. Miniature toggles are available with many of the same features as larger toggles.
If space isn’t an issue, using a stepped case could still be a benefit on the standard case to provide better clearances between terminals. This can help reduce the chance of accidental shorting of connections during installation.
5. How are you going to connect to the switch?
Quick connect tabs
Depending on the size of the case, you should consider a range of options. Screw terminals let you wrap wire directly or use forked termination spades. Quick connect terminals allow a quick plug-and-click spade, or solder terminals can be used for a fixed connection.
There is a method of an Internal Wiring Termination Style (IWTS) to push fit the cable for an internal pinch-style connection.
6. Would a military spec product be advantageous?
Even if it isn’t a military style application, the use of mil-spec products give peace-of-mind when it comes to overall reliability. It addresses the fact that parts are reliable in areas of high vibration or mechanical shock and there are no false activation risks.
7. What are your lever style requirements?
A normal lever would be a stainless steel ‘bat’ style, but some manufacturers offer a range of grips, levers, styles and colours for ease of identification. Careful selection of the lever can improve the ease of use of a machine.
By evaluating these considerations and potential trade-offs, you will find the best fit for reliable and efficient performance.
You can explore our range of toggle switches below and contact us if you need any guidance or support.