Devices with built in test buttons can and will fail. That is why they are designed to be tested.
I am talking about two electrical devices Ground fault Circuit interrupters (GFCI) and Arc Fault Circuit Interrupters (AFCI)
When I am performing a home inspection I will test these devices to make sure they are operating properly.
You will recognize the GFIs by the little buttons between the plugs on outlets located in spots where electrical shock hazards exist, such as in the bathroom, near the kitchen sink, in the garage etc. They’re designed to prevent electrical shock by “tripping,” or breaking the current when there is a ground fault. So, it’s clearly a good idea to push the test & reset buttons regularly to make sure they’re working. On most newer homes there will be two in the kitchen, one in the bathrooms and one either outside or in the garage. There may be more, for example if you have a spa tub, built in barbecue or have had additional outlets added outside, These outlets should be GFCI protected as well. A GFCI should protect the outlet it self and any outlet down stream from it.
AFCIs or Arc Fault Circuits started being required in 2000. These are special breakers installed in the electrical panel. They have a yellow, blue, green or white test button on them that when pressed should trip the breaker.
People that do a lot of vacuuming are learning to hate these little devices. They are designed to trip when there is an “Arc.” You know what I am talking about; you know when you are running the vacuum and try to go further than the cord allows. When the vacuum motor is drawing power and you disconnect the power source a small arc jumps from the outlet to the plug. This trips the breaker. Most adopted building codes only require these to protect the bedroom circuits, however newer codes require all circuits to be AFCI protected.
These are fairly new devices so the failure rate is still pretty high. During today’s home inspection in Chandler AZ I had two out of three AFCI breakers fail to trip when tested.
These little devices are there for your safety. If you test one and it fails, call a competent licensed electrician to perform repairs as needed.