A switch lock is a lock which is designed to integrate with a switch to control the operation of the switch. Switch locks limit use of the switch to someone with a key to the lock. There are a number of different designs for switch locks, and a wide range of uses for these tools; the highest quality products are usually made in accordance with safety and performance standards set out by companies such as Underwriters Laboratories (UL). These specialized locks are available in some hardware, electronics, and electrical stores, and they can also be ordered from manufacturers.
One use for a switch lock is on a simple on/off switch. The lock can be used to keep the switch in an on or off position to prevent accidental activation of the switch. This can be useful when a switch controls something critical and people want to prevent an accident. It can also be used to control switches in an environment like a school or a home with young children, in which children may play with the switch and cause a disruption, or accidentally turn something dangerous on; a garbage disposal, for example, could be controlled with a switch lock. In these cases, the lock may not have a key, with users simply needing to manually move the lock to move the switch.
Switch locks are also classically used in ignition interlock devices which are designed to prevent people from turning the ignition switch in a vehicle on. These devices are installed when drivers have a history of driving under the influence; before a driver will be allowed to operate a vehicle, he or she will have to blow into the device, which will unlock the ignition if no alcohol or very low levels of alcohol are detected on the driver's breath.
In high security facilities, switch locks are used to control switches so that they cannot be activated except by authorized personnel. This can be important in an environment like a server farm, where turning a switch off or on could have serious consequences, or in locations such as prisons and facilities where sensitive information is handled, where tight control of the facility is used to secure the area.
Manufacturers of switch locks make a variety of designs, ranging from a switch lock which can be installed on a home light switch very easily by someone with basic skills to more complex locks which must be installed by a professional because they are integrated into the system. If a switch lock is recommended for a particular application and people are not sure about what kind of lock to purchase, they should talk to an electrician about their options.