I was at a doctor’s office today and found this on the wall as I was leaving:
It’s a lock to hold a light switch on (or off).
The locks are not easy to find at a good price. I found some on ebay and Amazon, but not in local hardware stores. For a small piece of plastic, they are expensive, but they are probably a low-volume item and don’t benefit from an economy of scale.
There’s a second style that has a hole for the toggle. This alternate style has the advantage that it can’t be knocked out of place. From the photographs, it appears that installations benefit from a longer-than-normal screw to hold it securely.
A church I visit has a switch they want to keep on. Right now it is just held in place with packing tape. I’ll have to see if they’d like me to donate one of these. They look much more professional and don’t need an obligatory “please leave this switch on” message taped to the wall.
The reviews report another use for them: to protect switches that are part of a smart home system such as SmartThings, Wink, Google Home or Echo and Alexa. Reviewers also suggest using them with the switches for garage lights, outdoor lights and sump pump systems.