You replace the breaker to see if that fixes the problem. There simply is no other practical approach.
There exists testing equipment that will do this but it is much too expensive for general use.
The device that the breaker supplies voltage to does not work.
A non-auto circuit breaker is a circuit breaker with the trip element removed. Basically, it is a modified circuit breaker that is now a disconnect switch (glorified disconnect switch).
Replacement for American Switch single pole 15 amp circuit breaker
You may need to first switch it on before off.
In the electrical trade, this device is known as a circuit breaker.
No, this isn't necessary. The circuit breaker protects your home by avoiding an overcharging caused by a short-circuit. It's advisable blocking the access to the breaker.
If the test switch is faulty then there is no convenient way to determine if the GFCI is functioning, and technically, if the test switch is faulty, then as it is a part of the GFCI, the GFCI is faulty and should be replaced.
First you have to determine the cause before you can repair anything. It could be a blown fuse, bad circuit breaker, bad wiring, bad regulator, bad motor or a bad switch.
Bad switch or a short and tripped the breaker.
Bad bulbs, bad switch, bad circuit breaker, bad wiring, bad ground.
You have checked the wire at the switch? Breaker may be bad but not tripped. Loose connection at light or outlet that the switch controls. Use a screwdriver to touch the two terminals on the switch if you do not have a tester. May not be hot side of the circuit, but the neutral.
A breaker switch is easier to use.
a bad thermostat or miswire of the low voltage wiring or a bad heating relay stuck in the heating mode.
Bypass it to determine if that is the problem or test with an ohmeter if you have specs.
Bad ground.
Burned out bulbs Circuit breaker tripped Bad switch Bad ground
Bad switch? Bad relay/ Breaker tripped?
A non-auto circuit breaker is a circuit breaker with the trip element removed. Basically, it is a modified circuit breaker that is now a disconnect switch (glorified disconnect switch).